Home

AIRES user`s manual and reference guide

1. Particle stack manager Monitoring routines Particle data output Compressed output file s INTERACTION MODELS External Packages Figure 1 1 The structure of AIRES main simulation program 8 CHAPTER 1 INTRODUCTION Figure 1 1 contains a schematic representation of the modular structure of the main simulation programs Every unit consists of a set of subroutines performing the tasks assigned to the correspond ing unit In general every unit can be replaced virtually without altering the other ones In the case of the external interaction models where complete packages developed by other groups are linked to the simulation program via a few interface routines the modularity acquires particular importance since it makes it possible to easily switch among the various packages available The user controls the simulation parameters by means of input directives The Input Directive Language IDL is a set of human readable directives than provides a comfortable environment for task control After the input data is processed and checked control is transferred to the program s kernel During the simulations the particles of the cascade are generated and processed by several packages The interactions model package contains the physics of the problem The job control unit is responsible among other tasks of updating the internal dump file IDF This file contains all the relevant internal data used duri
2. Returned value Logical True if the positioning was successfully done False otherwise APPENDIX D THE AIRES OBJECT LIBRARY 153 croheaderinfo FORTRAN call croheaderinfo ouflag vrb irc C croheaderinfo amp ouflag amp vrb amp irc Printing a summary of the information contained in the header of the most recently opened compressed file Arguments ouflag Input integer Logical output unit s selection flag 0 or negative means FORTRAN unit 6 only 1 means unit 7 only 2 means both units 6 and 7 3 means unit 8 only ouflag gt 8 means unit ouflag only FORTRAN unit 6 corresponds to the standard output channel vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means successful return 154 croinputdata0 FORTRAN C APPENDIX D THE AIRES OBJECT LIBRARY call croinputdata0 intdata realdata shprimcode shprimwt croinputdata0 amp intdata 1 amp realdata 1 amp shprimcode 1 amp shprimwt 1 Copying into arrays some head
3. The integral in equation 2 8 cannot be solved analytically in the general case of an arbitrary geometry see page 214 If the Earth s curvature is not taken into account plane Earth then it is straightforward to prove that 2 9 where is the zenith angle of the shower axis see section 2 1 1 From this equation it comes out that X depends not only on h but also on and the location of the ground surface Unless otherwise specified any reference to atmospheric depth or depth is assumed to be a reference to X which may also be noted simply X 2 1 3 The slant depth and the Earth s curvature Many air shower observables especially the ground level distributions depend on the thickness of the air layer that separates the starting point of an air shower from the ground level For non vertical showers starting at the top of the atmosphere this thickness is measured in terms of the slant depth evaluated at ground level Xs zg The plane Earth approximation given by equation 2 9 is usually employed to evaluate that quantity However this approximate equation can give inaccurate estima tions for large zenith angles and in fact it is divergent for 90 3Notice that in some publications the symbol X is used to represent the slant depth 18 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES Zenith angle Curved Earth Plane Earth 1036 1 1036 1 1195 9 1196 4 1463 6 1465 3 2065 1 2072 2 3003 7 3029 4 5765 5 59
4. gt gt gt gt gt dd Mmm yyyy hh mm ss Beginning new task gt dd Mmm yyyy hh mm ss Initializing SIBYLL 1 6 package Initialization of the SIBYLL event generator eventual output from SIBYLL dd Mmm yyyy hh mm ss Initialization complete dd Mmm yyyy hh mm ss Starting simulation of first shower dd Mmm yyyy hh mm ss End of run number 1 CPU time for this run dd Mmm yyyy hh mm ss Writing ASCII dump file dd Mmm yyyy hh mm ss Task completed Total number of showers 2 dd Mmm yyyy hh mm ss Writing summary file dd Mmm yyyy hh mm ss End of processing Figure 3 2 continued CHAPTER 3 STEERING THE SIMULATIONS 57 Run control Includes all the parameters controlling the conditions of the simulations namely the total number of showers the number of showers per run the number of runs per process and the maximum CPU time per run The directives that control these variables are dynamic and may therefore vary during the simulations The quantities displayed in the input parameter listing correspond thus to instantaneous values of the mentioned parameters File names A listing with the names of all the files that will be created during the simulations ex cluding of course internal scratch files A detailed description of the output files that can be created by the simulation programs together with guidelines on how to manage them can be found in chapter 4 page 77 we just give here a brief descript
5. Comments and skipped lines are completely ignored They just appear in the input file Some times this is not convenient and it may be desirable to save their contents together with the output generated by the simulating program The Remark directive provides a mean to do this The state ment Remark JUST AN EXAMPLE placed in the example being discussed instructs AIRES to place the comment JUST AN EXAMPLE together with the output data There is no limit in the number of remark instructions that may appear inside a given input instruction set The Remark directive possesses another alternative syntax very useful for multi line text Rem amp eor This is the first line of a multi line remark This is the second line S p acc e s and TABS will be honored The label amp eor marks the end of the remark amp eor The directives that follow illustrate a very useful feature if the IDL which is the possibility of defining global variables Such variables can be used as replacement text within the IDL input stream and or be passed to output files or external modules called by AIRES The variables must be defined before they can be used This can be done by means of the SetGlobal directive The Import directive permits to import OS environment variables Variables can be overwritten and deleted using the DelGlobal directive The input data set continues with the TaskName and the three mandatory directives already in troduced in s
6. EB gt Wr then all the secondaries By Bn are kept Otherwise the standard Hillas algorithm is used e If n gt 3 then the standard Hillas algorithm is always used but if the weight of the single selected secondary wg happens to be larger than W then m copies of the secondary are kept for further propagation each one with weight w wg m The integer m is adjusted to ensure that Wy lt wg lt Wr In the AIRES algorithm Wy W 8 and the limit W is defined via W Ao Ern Wy 2 23 where Ag is a constant equal to 14 GeV and Wf is an external parameter which can be controlled by the user and that will be referred as the statistical weight factor In order to optimize the sampling algorithm it is advantageous to define different weight limits for different particle types In AIRES two weight factors are defined we and wy respectively 30 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES used when processing electromagnetic or heavy particles Parameter wh is specified indirectly by means of the user controlled ratio wes Arn a 2 24 Wi that permits evaluating wi from we Notice also that W depends on the absolute thinning energy En The constant Ag was adjusted so that Ap Ey gives approximately the position of the maximum of the all particles weight distribution see below If Wy oo the extended algorithm reduces to the standard Hillas procedure It is a simple exercise to show that this
7. Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel nweighted longit devel Ge Gg Geqeqacaqce Cc Cc Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development APPENDIX C OUTPUT DATA TABLE INDEX Low energy gamma rays Low energy electrons Low energy positrons Low energy muons Low energy muons Other charged low egy pcles Other neutral low egy pcles Low energy e and e Low energy mu and mu All low energy charged pcles All low energy neutral pcles All low energy pcles Low energy gam
8. Primary energy Primary zenith angle Primary azimuth angle Zero azimuth direction Thinning energy Injection altitude Ground altitude First obs level altitude Last obs level altitude Obs levels and depth step dd Mmm yyyy from standard input unit summary of the input directives IN EFFECT mytask 2 Infinite Infinite Infinite mytask lgf mytask idf mytask adf mytask grdpcles mytask lgtpcles mytask tNNNN mytask sry Site00 Lat 00 deg Long dd Mmm yyyy Proton 1 5000 Pev 15 00 deg 00 deg Local magnetic north 1 0000E 04 Relative 100 00 km 1 2829219E 03 g cm2 297 96 m 1000 000 g cm2 16 383 km 100 0000 g cm2 1 1733 km 900 0000 g cm2 41 20 000 g cm2 Figure 3 2 Sample AIRES terminal output 55 56 CHAPTER 3 STEERING THE SIMULATIONS Geomagnetic field Table energy limits MeV to 1 1250 Pev Table radial limits m to 2 0000 km Output file radial limits m to 12 000 km grdpcles m to 12 000 km lgtpcles ADDITIONAL PARAMETERS D Individual shower data Brief Cut energy for gammas 200 00 Cut energy for e e 200 00 Cut energy for mu mu 1 0000 Cut energy for mesons 1 5000 Cut energy for nucleons 150 00 Bartol inelastic mfp s On Gamma rough egy cut 2 0000 e e rough egy cut 2 0000 Hadronic Mean Free Paths SIBYLL SIBYLL switch On ISCELLANEOUS D Seed of random generator Automatic D Atmospheric model Linsley s standard atmosphere
9. doinstall ilev cfext ilev is an integer ranging from 0 to 4 indicating the level of installation 0 Complete installation of the AIRES system Necessary only when installing AIRES for the first time 1 Upgrade of an existing installation making the installed version the new current version 2 Recompiling All the simulation programs and the summary program are compiled and linked The AIRES object library is rebuilt 3 Relinking New executables for all the simulation programs and the summary program are created using the existing object files 4 Rebuilding the library The AIRES object library is rebuilt using the existing object files cfext is an optional argument It is a character string indicating that an alternative configuration file must be used to set the installation parameters If cfext is no null then the file config cfext is used instead of the default config file used when cfext is not specified To perform different compilation installation jobs it might be useful to have several configuration files For example the config file is first copied to a new config short file Then config short is edited changing the following parameters i The format for both ground and longitudinal tracking APPENDIX A INSTALLING AIRES AND MAINTAINING EXISTING INSTALLATIONS 113 compressed files is set to short ii The name of the executable program Aires is changed into Aires_sht Finally the command doinstall 2 short
10. limit of equation 2 11 2 1 4 Range of validity of the plane Earth approximation In section 2 1 1 page 11 it is specified that the limit of the plane Earth zone is located at a certain distance from the central z axis This distance varies linearly with the altitude and goes from 4 km at sea level up to 22 5 km at 100 km above sea level CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 19 To determine the boundaries of that zone that is a region where plane geometry can safely be used in the involved procedures the requirement of expressing the vertical depth of a given point with enough precision was taken into account The condition actually imposed can be defined in the following terms Let d be the horizontal distance of a certain point to the z axis and let z and z be the point s central and vertical altitudes Let AX d X Xa 2 2 12 In a plane geometry AX is zero for all d provided z is kept fixed We can use this quantity to determine a safe plane zone imposing a bound on AX After a series of technical considerations too many to be explained in detail here we concluded that the geometry can be acceptably taken as plane for all points whose distances to the z axis are less than dmax defined by the condition AX dmax lt 0 25 g cm AND 2AX dmax lt 1 x Xy z 2 13 Using equations 2 1 and 2 13 and taking into account that AX z z p z itis simple to obtain estimations
11. sprimname FORTRAN call sprimname pname pnamelen C sprimnamec amp pname amp pnamelen Getting the name of the special primary particle specified in the corresponding IDL instruction This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments pname Output string The name of the special particle The calling program must ensure there is enough space to store the string pnamelen Output integer Length of particle name 212 APPENDIX D THE AIRES OBJECT LIBRARY thisairesversion FORTRAN iavers thisairesversion C iavers thisairesversion Returning the current version of the AIRES library Returned value Integer The corresponding version in integer format for example the num ber 01040200 for version 1 4 2 01040201 for version 1 4 2a etc APPENDIX D THE AIRES OBJECT LIBRARY 213 urandom FORTRAN r urandom C r urandom This function invokes the AIRES random number generator and returns a pseudo random num ber uniformly distributed in the interval 0 1 It is necessary to initialize the random series calling raninit before using this function Returned value Double precision The uniform pseudo random number urandomt FORTRAN r urandomt threshold C r urandomt threshold This function invokes the AIRES random number generator and returns a pseudo random num ber uniformly distributed
12. crossed observing levels key 91 100 192 crotaskid see AIRES object library depth of first interaction 76 78 79 85 141 199 dielectric suppression v 3 4 22 70 118 125 dumpfileversion see AIRES object library dumpfileversiono see AIRES object library dumpinputdata0 see AIRES object library Earth s curvature 4 9 11 17 18 79 225 Earth s magnetic field see geomagnetic field EHSA see extended Hillas splitting algorithm energy distributions 2 4 27 28 38 67 80 118 140 error messages 46 exotic primaries see special primary particles exported data files 54 57 60 79 106 117 119 137 for single showers 119 extended Hillas splitting algorithm 3 4 68 221 external packages v 3 5 8 20 23 64 65 68 79 117 120 122 123 126 170 fault tolerant processing 8 58 101 file directories see AIRES file directories first shower number 85 121 INDEX fitghf see AIRES object library Gaisser Hillas function 79 81 100 171 183 185 fitting 170 inverse of 184 gamma ray conversion in the geomagnetic field 222 GEANT particle codes 94 146 geographic azimuth 62 129 154 geomagnetic field 2 4 8 11 19 40 64 117 123 155 226 fluctuations 65 123 getcrorecord see AIRES object library getcrorectype see AIRES object library getglobal see AIRES object library getinpint see AIRES object library getinpreal see AIRES object library getinpstrin
13. is executed This will generate several new executable programs namely Aires_sht Aires_shtQ Aires_shtS16 and Aires_shtQ99 which will be capable of producing compressed files with short format particle records Appendix B IDL reference manual Both the main simulation programs Aires and AiresQ and the summary program AiresSry use a common language to receive the user s instructions This language is called Input Directive Language IDL and currently consists of some 70 different instructions to set simulation parameters control the output data etc In this section we list alphabetically ordered all AIRES 2 6 0 IDL directives The IDL directives can be written using no special format with one directive per line there are no continuation lines but each line can contain up to 176 characters The directives start with the directive name followed by the corresponding parameters All the words that form a sentence must be separated by blanks and or tab characters All directives are scanned until either an End directive or an end of file is found Most directives can be placed in any order within the input stream The Input directive permits inserting instructions placed in separate files letting the user to conveniently organize complex input data sets Input directives can be nested Dynamic can be set every time the input file is scanned static can be set only at task initial ization time and hidden associated wi
14. 20 20 15 16 17 18 on OQ 11 10 22 14 14 13 13 95 MOCCA B G D nG OO O Gaa ee pe e v N 14 Table 4 7 Elementary particle codes corresponding to several commonly used coding systems The routines that process AIRES compressed output files allow the user to select any one of these coding schemes 96 CHAPTER 4 MANAGING AIRES OUTPUT DATA Opening existing files Once the proper environment is set up by means of the initializing routine the system is ready to open any existing compressed file The open routine opencrofile will use the header information to initialize the internal variables that permit processing the different fields defined for the file The following example illustrates how to open a file program sample character 80 mydir myfile integer channel irc call ciorinit 0 1 0 irc call opencrofile mydir myfile 0 10 4 channel irc myfile and mydir are character strings containing respectively the file name and the directory where it is placed The integer argument 10 indicates that the logarithmic fields are going to be transformed into decimal logarithms channel is an output parameter identifying the opened file it should not be set by the calling program It is important to remark that this call will transparently open any compressed file regardless of its type or format ground particle as well as longitudinal tracking particle files in al
15. All the entered remarks will be printed in the log and summary files and stored in different output data files There is no limit in the number of remark lines but every line cannot be longer than 75 characters ResamplingRatio Syntax ResamplingRatio rsratio Default ResamplingRatio 10 s This directive sets the variable s used in the resampling algorithm defined in section 4 2 1 page 90 rsratio is a real number that must be greater or equal than 1 RLimsFile Syntax RLimsFile filext rmin rmax Default RLimsFile any file 250 m 12 km s This directive defines the lateral limits for the compressed data file whose extension is filext For the ground particle file rmin and rmax define together with the resampling ratio that is controlled by the IDL instruction ResamplingRatio the radial limits of the zone where the particles are going to be saved see page 90 In the case of longitudinal tracking particle files those parameters define the inclusion zone at ground level At an arbitrary altitude the particles are included accordingly with the rules explained in section 4 2 1 page 84 RLimsTables Syntax RLimsTables rmin rmax Default RLimsTables 50 m 2 km s This directive defines the radial interval to use in the lateral distribution tables histograms Each lateral distribution histogram consists of 40 logarithmic bins starting with rmin lower radius of bin 1 and ending with rmax upper radius of bin 40 RunsPerPro
16. The complete list of available tables is placed in appendix C page 137 No tables are exported or printed if no Export or Print directives are included within the input data Notice also that there are several options that modify the resulting output Such options control the normalization of histograms output format etc A more detailed discussion on this subject is placed in section 4 1 page 77 It is strongly recommended to edit a plain text file containing some IDL directives run the simu lation program and analyze the obtained output In UNIX environments this can be made by means of the command Aires lt myfile inp or alternatively AiresQ lt myfile inp myfile inp is the name of the file containing the IDL directives Input data listing The output typed at the terminal by any of the simulation programs will be similar to the sample displayed in figure 3 2 Among other data AIRES standard output includes a listing of the most important input parameters All the parameters that are not explicitly set will take a default value When default values are in effect it is indicated with a D symbol placed before the parameter s description All The variables included in this list can be modified by means of IDL instructions The input parameter listing is divided in sections accordingly with the different kind of variables that control the computational and physical environment of the simulations These sections are 4som
17. gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place nobslev Output integer The number of observing levels olzv Output double precision array Altitudes in m of the corresponding observing levels from 1 to nobslev The calling program must ensure that there is enough space for this array oldepth Output double precision array Vertical atmospheric depth in g cm of the corresponding observing levels from 1 to nobslev The calling program must ensure that there is enough space for this array irc Output integer Return code 0 means successful return APPENDIX D THE AIRES OBJECT LIBRARY 157 croreccount FORTRAN call croreccount channel vrb nrtype nrec irc C croreccount amp channel amp vrb amp nrtype 0 amp nrec amp irc Counting the records of a compressed file starting from the first non read record Once the file was scanned the corresponding I O channel is left in end of file status Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 m
18. return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place datype Output integer The data type that corresponds to the specified field 1 for integer data 2 for date time data and 3 for real data irc Output integer Return code 0 means successful return Returned value Integer The field index Zero if there was an error 150 APPENDIX D THE AIRES OBJECT LIBRARY crofileinfo FORTRAN call crofileinfo channel ouflag vrb irc C crofileinfo amp channel amp ouflag amp vrb amp irc Printing information about the records of an already opened compressed file This routine retrieves information about the complete record structure of the corresponding file How many record types are defined and for each record type the number of fields and a list of their names and relative logical positions The ordering in the list of fields is equal to the ordering of data in the integer and real arrays returned by routine getcrorecord when reading a record of the same type Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile ouflag Integer inpu
19. see page 61 like in the following example AddSpecialParticle SSP1 module l AddSpecialParticle SSP2 module 2 PrimaryParticle SSP1 0 2 PrimaryParticle SSP2 0 3 PrimaryParticle Proton 0 5 In this case the primary will be SSP1 SSP2 or proton with probabilities 20 30 and 50 respectively 3 5 2 The external executable modules Every time a special primary shower is started the simulation program will invoke the executable module associated with the corresponding primary defined using the AddSpecialParticle directive Such an executable program can be a FORTRAN C or C program or a shell script running it and must be capable of providing the calling module with the list of primary particles that will be added to the particle stacks before starting the simulation of that shower The simulation program and the external module communicate via internal files in a way that is transparent for the user and completely portable The AIRES object library includes a series of user friendly routines callable from FORTRAN C or C that ease the task of writing such external modules Figure 3 3 displays a brief FORTRAN program with the basic structure needed in every module capable of building a list of primary particles to start the simulation of a shower The program starts with a call to routine speistart and ends with a call to speiend It is essential to maintain this structure in any external module All the calls to any AIRES lib
20. 0 a a 82 Processing compressed data files an example ooo 99 List of Tables 1 1 2 1 2 2 2 3 2 4 3 1 3 2 4 1 4 2 4 3 4 4 4 5 4 6 4 7 Main characteristics of the AIRES air shower simulation system Linsley s model coefficients for the US standard atmosphere Total shower axis length and slant path versus zenith angle AIRES particle codes and names 000000022 ee eee AIRES particle groups 2 1 ee ee Physical units accepted within IDL directives 0 0 0 Predefined sites of the AIRES site library 00 0 Fields contained in the beginning of shower record of compressed particle files Fields contained in the end of shower record of compressed particle files Fields contained in the external primary particle record of compressed particle files Fields contained in the special primary trailer record of compressed particle files Fields contained in the particle records of compressed ground particle files Fields contained in the particle records of compressed longitudinal tracking particle files Aae yA i Sadi Bick e ah Rh A oe RAE Ss Shree Stes xi 85 86 88 88 89 xii Chapter 1 Introduction Cosmic rays with energies larger than 100 TeV must be studied at present using experimental devices located on the surface of the Earth This implies that such kind of cosmic rays c
21. 2913 2991 2992 2993 3001 3005 3007 3091 3092 3291 3292 3293 5001 5005 5006 5007 5008 5011 5012 5013 5014 5021 5022 5023 5041 5091 5092 5205 5207 5211 5213 5291 5292 5293 5501 5511 5513 Table name Unweighted energy distribution e and e nweighted energy distribution mu and mu nweighted energy distribution pi and pi nweighted energy distribution K and K nweighted energy distribution All charged particles nweighted energy distribution All neutral particles nweighted energy distribution All particles aG coc Mean arrival time distribution Gamma rays Mean arrival time distribution Electrons and positrons Mean arrival time distribution Muons Mean arrival time distribution Other charged pcles Mean arrival time distribution Other neutral pcles Mean arrival time distribution All charged particles Mean arrival time distribution All neutral particles Mean arrival time distribution All particles Number and energy of ground gammas versus shower number Number and energy of ground e versus shower number Number and energy of ground e versus shower number Number and energy of ground mu versus shower number Number and energy of ground mu versus shower number Number and energy of ground pi versus shower number Number and energy of ground pi versus shower number Number and energy of ground K versus shower number Number and energy of groun
22. 30 It is therefore necessary to use a smaller weight limit to modify the corresponding distribution of weights This is the case of figure 2 11 that corresponds to the case Wi wih yeg It is worthwhile mentioning that the weight distributions corresponding to other thinning energies have the same shape as the ones plotted in figure 2 11 page 35 but present a global shift in the abscissas scale which is proportional to the logarithm of the thinning level for example the weights for the 10 distribution are one order of magnitude lower than the ones for 107 and so on The improvement in the lateral distribution plots is of course not free The CPU time per shower is increased when Wy decreases Figure 2 12 page 35 represents the CPU time consumption per 34 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES p m 0 1000 2000 0 1000 2000 0 1000 2000 r m r m r m 10 c10 lt 10 E zZ 10 z 10 z 107 10 10 10 10 10 10 1 1 1 1 1 1 10 10 10 W 2 2 10 10 10 3 3 3 10 10 10 E 4 10 10 10 0 1000 2000 0 1000 2000 0 1000 2000 r m r m r m Figure 2 10 Effect of the AIRES extended thinning on the fluctuations of the lateral distribution of electrons and positrons The plots correspond to 10 eV proton showers simulated with Ein prim 1075 and different weight factors wy wy W The yellow bands correspond to simulations performed in similar conditions but using the Hillas algorithm at 1077 re
23. 3e 10 lao laz 2e 10 S 2e 10 5 1e 10 1e 10 Fi J 0 fi fi fi 0 NR a fi fi fi 0 200 400 600 800 1000 0 200 400 600 800 1000 X g em2 X g em2 Figure 2 7 Effect of the thinning energy on the fluctuations of the number of charged particles crossing the different observing levels during the shower development Ten 10 eV vertical proton showers were averaged to obtain the data for each thinning level The plots labeled a b c d correspond to En Eprim 1073 1074 10 and 1077 respectively reduce immediately when the thinning is lowered Compare for example with the plots of figure 2 7 page 31 To understand the behavior of these distributions it is necessary to recall that the muons are very penetrating particles that is they undergo a very reduced number of interactions before reaching ground Therefore their statistical weights remain small since they are products of a few factors and this fact is responsible for the low level of fluctuations produced On the other hand ground electrons and positrons most likely come out after a long chain of processes involving many predecessor particles and in such circumstances very large statistical weights are unavoidable and hence the high level of fluctuations observed in the e e distribution of figure 2 8 page 32 The AIRES extended thinning algorithm can be useful to reduce such kind of fluctuations To illustrate this point let us consider the sa
24. 96 175 getinpint 96 176 187 getinpreal 96 177 187 getinpstring 96 178 187 getinpswitch 96 179 187 getlgtinit 98 180 181 getlgtrecord 98 180 181 ghfin 100 184 ghfpars 100 183 184 185 ghfx 100 185 grandom 100 186 197 idlcheck 96 187 loadumpfile 96 167 169 188 nuclcode 75 189 nucldecode 190 olcoord 100 191 olcrossed 100 192 olcrossedu 100 193 olsavemarked 100 194 olv2slant 100 195 opencrofile 96 99 144 196 raninit 100 186 197 213 regetcrorecord 100 174 198 splstint 76 199 spaddnu11 75 200 spaddp0O 72 73 75 201 spaddpn 75 202 speiend 72 74 76 203 speigetmodname 75 204 speigetpars 75 205 speimv 76 206 232 speistart 72 76 208 speitask 75 209 spinjpoint 76 207 spnshowers 75 210 sprimname 75 211 thisairesversion 96 212 urandom 100 197 213 urandomt 73 74 100 197 213 xslant 100 214 AIRES particle codes 20 21 73 94 146 201 202 AIRES Runner System v 5 48 101 216 220 225 commands airescheck 101 airesexport 106 aireskill 103 aireslaunch 102 104 airesstatus 102 airesstop 103 airestask 102 105 airesuntask 103 mkairesspool 105 rmairesspool 105 AIRES site library 48 64 115 123 134 AIRES summary program vi 2 5 45 57 77 79 107 114 AiresIDF2ADF see AIRES IDF to ADF converting program airesrc initialization file 101 102 106 111 AiresSry see AIRES summary program alternative primari
25. AIRES 2 6 0 These tables can be processed using directives PrintTables and or ExportTables see chapter 3 Code Table name 1 1001 Longitudinal development Gamma rays 2 1005 Longitudinal development Electrons 3 1006 Longitudinal development Positrons 4 1007 Longitudinal development Muons 5 1008 Longitudinal development Muons 6 1011 Longitudinal development Pions 7 1012 Longitudinal development Pions 8 1013 Longitudinal development Kaons 9 1014 Longitudinal development Kaons 10 1021 Longitudinal development Neutrons 11 1022 Longitudinal development Protons 12 1023 Longitudinal development Antiprotons 13 1041 Longitudinal development Nuclei 14 1091 Longitudinal development Other charged pcles 15 1092 Longitudinal development Other neutral pcles 16 1205 Longitudinal development e and e 17 1207 Longitudinal development mu and mu 18 1211 Longitudinal development pi and pi 19 1213 Longitudinal development K and K 20 1291 Longitudinal development All charged particles 21 1292 Longitudinal development All neutral particles 22 1293 Longitudinal development All particles 23 1301 Unweighted longit development Gamma rays 24 1305 Unweighted longit development Electrons 25 1306 Unweighted longit development Positrons 137 138 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 5
26. AIRES version includes 48 new longitudinal development tables corre sponding to the following observables e Number of low energy particles versus atmospheric depth e Energy of low energy particles versus atmospheric depth e Deposited energy ionization versus atmospheric depth All the AIRES output tables are listed in appendix C Appendix F AIRES History This appendix briefly summarizes the history of the AIRES simulation system starting from the current version 2 6 0 dated 11 July 2002 backwards to the first public release version 1 2 0 dated 03 May 1997 AIRES version 2 6 0 11 Jul 2002 This version of AIRES consists of about 670 routines adding up to more than 94 000 lines of source code Features 1 New version of SIBYLL SIBYLL 2 1 hadronic model 2 New version of QGSJET QGSJETO1 hadronic model 3 Nucleus nucleus cross sections and nuclear fragmentation are now processed via the external hadronic packages SIBYLL or QGSJET 4 The algorithm saving ground particles into compressed files were improved to exactly account the arrival times of heavy neutral particles like neutrons 5 Nuclear codes were extended beyond iron up to Z 36 6 The simulation and summary programs can generate a task summary script file extension tss containing the most relevant data associated with the simulations in the format Keyword value suitable for processing by other programs 7 Complete revision of the AIRE
27. ForceLowEAnnihilation 70 121 217 218 ForceLowEDecays 70 122 217 218 ForceModel1Name 69 122 GammaCutEnergy 52 122 219 GammaRoughCut 70 122 219 223 GeomagneticField 65 123 GroundAltitude 50 51 63 123 GroundDepth synonym of GroundAltitude 123 Help 48 123 Import 50 51 124 218 InjectionAltitude 63 124 InjectionDepth synonym of InjectionAltitude 124 Input 47 48 60 114 124 124 InputListing 58 70 124 InputPath 60 115 124 124 204 LaTex 78 125 LPMEffect 70 125 MaxCpuTimePerRun 58 125 MesonCutEnergy 52 125 219 MFPHadronic 69 126 MFPThreshold 69 126 MinExtCollEnergy 68 126 216 MinExtNucCollEnergy 68 126 216 234 MuonBremsstrahlung 70 127 218 MuonCutEnergy 52 127 219 NuclCollisions 69 127 NuclCutEnergy 52 127 219 ObservingLevels 51 63 67 93 128 OutputListing 78 128 PerShowerData 67 80 119 128 PhotoNuclear 69 128 PrimaryAzimAngle 50 62 129 PrimaryEnergy 46 51 61 71 129 218 PrimaryParticle 46 51 61 71 129 PrimaryZenAngle 50 51 62 130 PrintTables 52 54 79 130 137 Prompt 48 130 PropagatePrimary 69 130 RandomSeed 67 131 RecordObsLevel1s 93 131 Remark 50 51 131 ResamplingRatio 89 92 132 132 RLimsFile 89 92 132 RLimsTables 67 132 RunsPerProcess 58 132 SaveInFile 53 90 92 93 132 SaveNot InFile 53 90 92 133 SeparateShowers 133 SetGlobal 50 51 133 218 Set TimeAt Injection 70 133 ShowersP
28. Getting the record type of the record which is located next to the last read record of the com pressed file identified by argument channel The action of this routine consists in reading the first part of the record to obtain the record type and then skip the remaining part to position the file at the end of the corresponding record The use of this routine is recommended whenever only the record type is needed since it is faster than getcrorecord When additional data of an already scanned record is required routine regetcrorecord can be used to re scan the last processed one Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place infield1 Output integer If rectype is zero this variable contains the current value of the first integer field of the record which is in general a particle code Otherwise it is set to
29. Nmax Number of particles at shower maximum 8 X0v Fitted parameter Xo vertical of Gaisser Hillas function equation 4 1 9 Lambda Fitted parameter vertical of Gaisser Hillas function equation 4 1 10 SofSqr Normalized sum of squares equation D 1 from the longitudinal profile fit 11 FitRe Return code of the longitudinal profile fit 82 CHAPTER 4 MANAGING AIRES OUTPUT DATA AIRES TSS version V V V gt gt gt gt gt gt This is AIRES version V V V dd Mmm yyyy gt gt gt Compiled by gt gt gt USER xxxxx HOST xxxxx DATE dd Mmm yyyy gt gt gt TSS file for task mytask Program and compilation parameters AiresVersion V V V Units LengthUnit m TimeUnit sec EnergyUnit GeV DepthUnit g cm2 AngleUnit deg MagneticFieldUnit nT General data TaskName mytask TaskVersion 0 TotalShowers 3 CompletedShowers 3 Other general data Basic Input Parameters Site Site00 SiteLatitude 0 000000 SiteLongitude 0 000000 EventDate dd Mmm yyyy NumberOfDifferentPrimaries 1 PrimaryParticle Proton PrimaryParticleCode 31 Other task input parameters Parameters relative to each shower ShowerPerShowerKey PrCode PrEgy Zenith Azim DataSh000001 31 350000 0 00000 DataSh000002 31 350000 0 00000 DataSh000003 cel 350000 0 00000 End of tss Figure 4 1 Sample AIRES task summary script TSS file 0 00000 0 00000 0 000
30. THE AIRES OBJECT LIBRARY 167 dumpfileversion FORTRAN ivers dumpfileversion C ivers dumpfileversion Returning the AIRES version associated with the dump file that was most recently read in this can be done using routine loadumpfile Returned value Integer The corresponding version in integer format for example the num ber 01040200 for version 1 4 2 01040201 for version 1 4 2a etc If there is an error then the return value is negative 168 APPENDIX D THE AIRES OBJECT LIBRARY dumpfileversiono FORTRAN ivers dumpfileversiono C ivers dumpfileversiono Returning the AIRES version used to write for the first time the original version the dump file that was most recently read in this can be done using routine loadumpfile Returned value Integer The corresponding version in integer format for example the num ber 01040200 for version 1 4 2 01040201 for version 1 4 2a etc If there is an error then the return value is negative APPENDIX D THE AIRES OBJECT LIBRARY 169 dumpinputdata0 FORTRAN call dumpinputdata0 intdata realdata C dumpinputdata0 amp intdata 1 amp realdata 1 Copying into arrays some global input data parameters stored in the dump file that was most recently read in this can be done using routine loadumpfile that are not returned by croin putdata0 Arguments intdata Output integer array Integer data array The calling program must provide enough
31. The program is stopped without taking any further action This directive is useful to end an interactive session ExportPerShower Syntax ExportPerShower On Off Default ExportPerShower is equivalent to ExportPerShower On ExportPerShower Off is assumed in case of missing specification d This directive affects only those tasks simulated with the PerShowerData Full option see page 128 If ExportPerShower On is specified then a set of plain text files one file per simulated shower will be written for all the tables selected for exporting see directive Ex portTables Each one of these single shower tables contains the values adopted by the corresponding observable in the respective shower The normal table containing the average over showers is also exported and is not affected by this directive ExportTables Syntax ExportTables mincode maxcode Options optstring ExportTables Clear Default No tables are exported by default d Tables whose codes range from mincode to maxcode are selected for exporting as plain text files If maxcode is not specified it is taken equal to mincode The table codes are integers A 120 APPENDIX B IDL REFERENCE MANUAL complete list of available tables more than 180 is placed in appendix B or can be obtained with directives Help tables and or TableIndex The Clear option permits clearing the list of exported tables thus overriding all the previous ExportTables directives o
32. TotalShowers Site Syntax Site name Default Site Site00 s The Site directive specify the geographical location that define the environment latitude longitude and altitude where the simulations take place name is a string identifying the se lected site It must either be one of the predefined sites of the AIRES site library listed in table 3 2 page 64 or have been previously defined by means of the AddSite directive Skip Syntax Skip amp label d Instruction to skip part of an input data stream All directives placed after the Skip statement and before amp label are skipped Notice that this is not a go to statement It is only possible to skip forwards never backwards SpecialParticLog Syntax SpecialParticLog lvl Default SpecialParticLog is equivalent to SpecialParticLog 1 SpecialParticLog 0 is assumed in case of missing specification d Controlling the amount of data related with special primary particles to be saved in the corresponding log file Ivl is an integer parameter that can take the following values 0 No information written in the log file 1 Messages before and after invoking the external module 2 Level 1 plus detailed list of valid primaries StackInformation Syntax StackInformation On Off Default StackInformation is equivalent to StackInformation On StackInformation Off is assumed in case of missing specification d Directive to instruct AIRES to print detailed stack usage i
33. at all ForceLowEDecays ForceLowEAnnihilation These directives control the kind of action to be ta ken when low energy particles that can decay or undergo annihilation reach the low energy threshold LPMFffect IDL switch to enable disable the LPM 19 24 effect The default is LPMEffect On DielectricSuppression IDL switch to enable disable the dielectric suppression 19 25 effect The default is DielectricSuppression On MuonBremsstrahlung IDL switch to enable disable the muon bremsstrahlung and muonic pair pro duction processes The default is MuonBremsstrahlung On AirZeff AirAvgZ A AirRadLength IDL directives associated with internal parameters For a de tailed explanation see appendix B page 114 Since most of these IDL instructions are hidden directives see page 58 the respective settings in effect will not be included in the input data list unless explicitly indicated by means of directive In putListing see page 124 Additionally warnings messages will be issued when using any directive which may lead to simulations with unphysical results 3 5 Special primary particles In many cases of interest it is necessary to simulate showers that cannot be described adequately with the usual scheme of a single primary particle interacting with a nucleus in the atmosphere and generating a set of secondaries to be propagated Instead one has that a particular set of interac tions that only affect the primary particle ori
34. been solved Some of the default settings in the config file have been changed Input Directive Language The number in brackets placed after directive names indicate the page where the corresponding di rective is described New features e Support for defining global variables that can either be used within the IDL input stream or passed to the output files or external modules See section 3 2 5 page 50 e New supported units inches in feet ft yards yd miles mi and Joules J See table 3 1 page 49 New directives e Brackets 116 e DelGlobal 117 e EMtoHadronWFRatio 119 e ForceLowEAnnihilation 121 e ForceLowEDecays 122 e Import 124 e MuonBremsstrahlung 127 e SetGlobal 133 Directives no longer supported e HadronCutEnergy Obsolete Hillas splitting algorithm parameter It has no equivalent in the current implementation of the algorithm e HeavyMineko Parameter of the heavy particle knock on algorithm The current ver sion of the algorithm uses only compile time parameters that generally do not need to be changed by the user Directives related to parameters which changed their default values or parameter ranges e PrimaryEnergy 129 e ElectronCutEnergy 118 e ElectronRoughCut 118 APPENDIX E RELEASE NOTES 219 e GammaCutEnergy 122 e GammaRoughCut 122 e MesonCutEnergy 125 e MuonCutEnergy 127 e NuclCutEnergy 127 Output data Output tables The current
35. checks and then exits without starting the simula tions This directive is useful for input file debugging CommentCharacter Date Syntax CommentCharacter char nnn Default The default comment character is d The plain text files produced with the ExportTables directive can have heading and trailing lines All these lines start with a comment character in their first column The default comment character is normally OK but if the Export ed files could be used as input of another program a plotting utility for example which recognizes a different comment character in such cases the CommentCharacter directive permits setting this mentioned character char can be any single character with no quotes Alternatively the comment character can be specified by means of its ASCII decimal code expressed in the form of a three figure number nnn This permits using non printable comment characters as well as resetting the comment character to Syntax Date fpyear Date year month day Default The current date at the moment of invoking the program s This directive sets the date assumed for the simulations The date is used at the moment of evaluating the geomagnetic field by means of the IGRF model see sections 2 1 5 and 3 3 4 Setting the date may be necessary when performing simulations with the purpose of analyzing a certain air shower event reported by an experiment The date can be specified either as
36. density In the other extreme the nucleonic component represented in figure 2 15 by the proton and neutron lateral distributions concentrates in a relatively narrow zone around the shower axis On the other hand even if the muon density is always smaller than the electromagnetic counterpart it diminishes more slowly with the distance to the core so the muon electromagnetic ratio results an increasing quantity The energy spectra of the particles reaching ground constitutes also an important observable to CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 39 le 10 le 09 1e 08 a 1e 07 Z 1e 06 1e 05 Figure 2 16 Same as figure 2 15 but for the energy le 04 distributions of particles wi ii a EE E E O reaching ground level 0 01 0 1 1 10 100 1000 Energy GeV take into account in the analysis of air showers In figure 2 16 such distributions are plotted for the same 1078 relative thinning single shower mentioned in the preceding paragraphs The outstanding fact related to these graphs is that the gamma and e e energy distribution have their maximums for much lower energies than the corresponding to the maxima of muons pions and nucleons Therefore even if the electromagnetic component of the shower accounts for the principal fractions of particle number and energy see figures 2 13 and 2 14 the individual particles are relatively less energetic when compared with the average muons pions and nucleons Another rele
37. displaying a series of results related with the already finished simulations a task summary script file can also be created As it will be discussed in this section there are several IDL directives that allow controlling such AIRES output data The summary program AiresSry which is part of the AIRES system allows the user to process the simulation data contained within the internal dump file IDF or equivalently the portable dump file ADF and retrieve any of the available observables similarly as the main simulation programs do It is worthwhile mentioning that AiresSry can be used before as well as after the simulations are finished In the first case it is possible to monitor the development of the simulation task while the former alternative is most convenient for analysis tasks Backwards compatibility is always ensured Old IDF s or ADF s generated with any previous version of AIRES can be processed normally using AiresSry Many observables are of tabular nature that is an array of data whose elements correspond to a set of values of a determined variable For example the longitudinal development of the number of gamma rays is represented by an array whose elements give the number of gamma rays that have crossed the different observing levels as a function of the observing level altitude Most of the tabular observables commonly defined are automatically calculated by the simulation programs The corresponding data arrays
38. distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Gamma rays Electrons Positrons Muons Muons Pions Pions Kaons Kaons Neutrons Protons Antiprotons Nuclei Other charged pcles Other neutral pcles e and e mu and mu pit and pi K and K All charged particles All neutral particles All particles nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution nweighted energy distribution qq Geqeeeaceqedcaecd Cc Gamma rays Electrons Positrons Muons Muons Pions Pions Kaons Kaons Neutrons Protons Antiprotons Nuclei Other charged pcles Other neutral pcles APPENDIX C OUTPUT DATA TABLE INDEX 141 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 Code 2905 2907 2911
39. energy since it depends strongly on the initial conditions of the simulation for example the inclination of the shower The hadronic character of the shower at its beginning shows up clearly when considering the pions plot At high altitude the energy carried by the pions represent a large fraction of the total energy then this energy reaches a maximum and diminishes monotonically as long as the shower develops The examples here presented are just to illustrate some general aspects of the air showers The corresponding data need not accurately reproduce actual experimental data This observation applies especially to the number of ground muons which seems to be strongly dependent on the hadronic model used in the simulations CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 37 8 10 12 E E w 10 Z 10 10 104 10 0 200 400 600 800 1000 X g cm Figure 2 13 Longitudinal development of 3 x 10 eV vertical proton showers The error bars correspond to one RMS error of the mean and are generally smaller that the symbols The primary particles are injected at the top of the atmosphere and the ground is located at 300 m a s l The longitudinal development is recorded in 75 different observing levels 13 g cm apart The average position of the shower maximum is Xmax 906 6 5 1 g cm Energy fraction 0 200 400 600 800 1000 X g em Figure 2 14 Energy longitudinal development of 3 x 107 eV vertical proton showers the condi
40. file processed and with the record type see also argument ire and routine crofileinfo altrec Output logical True if the corresponding record type is positive alternative record type False if the record type is zero default record type vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only APPENDIX D THE AIRES OBJECT LIBRARY 173 error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means that a record with zero default record type was successfully read 2 gt 0 means that an alternative record of type 7 was successfully read 1 means that an end of file condition was got from the corresponding file Any other value indicates a reading error ire equals the system return code plus 10000 Returned value Logical True if a record was successfully read False otherwise End of file or I O error 174 APPENDIX D THE AIRES OBJECT LIBRARY getcrorectype FORTRAN okflag getcrorectype channel vrb infieldl rectype C okflag getcrorectype amp channel amp vrb amp infield1 amp rectype
41. grdpcles gamma Saving the ASCII portable version of the IDF file ADF after finishing the simulations No tables are printed or exported if no PrintTables ExportTables directives are explicitly used PrintTable 1291 PrintTable 1707 PrintTable 2207 Opt d PrintTable 3001 Opt M ExportTable 2793 Opt M Exported tables are placed in separate ExportTable 5501 plain text files for further processing e g plotting Longit devel of all charged particles Energy longitudinal development of muons Setting some options Here too End End of input data stream Figure 3 1 continued CHAPTER 3 STEERING THE SIMULATIONS 53 g cm see page 123 On the other hand the statement ObservingLevels 41 100 g cm2 900 g cm2 sets the variables No x and xe of equation 2 19 The IDL instructions continue with five directives that fix the cut energies for different particle kinds Every particle whose kinetic energy falls below the threshold corresponding to its kind will be no more propagated by the simulation program as explained in section 2 2 3 page 23 There are many observables that can be defined and studied to determine the behavior of air showers with given initial conditions Generally only a small fraction of these observables are of interest for a determined user and of course the set of relevant observables do vary with the particular problem being studied These somewhat contradictory facts we
42. gt gt gt gt gt dd Mmm yyyy hh mm ss Reading data from standard input unit where V V V indicates the current version of AIRES 2 6 0 and goes together with the release date Type x and press ENTER to leave the program If step 3 ended successfully and you fail to run the program it is likely that the AIRES bin directory is not in your environment search path Unix environment variable PATH In some systems you need to log out and log in again to make effective any PATH change If you cannot place the AIRES bin directory into your account s PATH then ask a Unix expert to do that for you Once you are sure that the directory is in the search path and if the problem still persists check if the executable file Aires exists If it does not exist that means that step 3 was not successfully completed Do not continue with the next step until you succeed with this one 5 cd to your HOME directory and verify the presence of a file named airesre Normally it is not necessary to change anything in this file but the need may appear in the future specially if you decide to use the UNIX scripts that are provided to help running AIRES see chapter 5 6 If you completed successfully these steps the software should be properly installed 7 After successfully completing these steps you can delete the files corresponding to old ver sions of AIRES Such files are placed within the Aroot directory For example directory 1 2 0 contains AIR
43. improvement of the MOCCA code allowing the user to comfortably perform simulations based on the extensive knowledge on air shower processes that is contained in MOCCA s source lines It is important to remark however that the present version of AIRES does include many mod ifications to the original algorithms which can alter the program s output with respect to that from MOCCA This implies that both programs are no longer equivalent Another characteristic of ultra high energy simulations that was taken into account when develop ing AIRES is the large number of particles involved For example a 102 eV shower contains about 10 secondary particles From the computational point of view this fact has two main consequences that were specially considered at the moment of designing AIRES i With present day comput ers it is virtually impossible to follow all the generated particles and therefore a suitable sampling technique must be used to reduce the number of particles actually simulated The so called thin ning algorithm introduced by Hillas 4 or the sampling algorithm of Kobal Filip i and Zavrtanik 5 represent examples of such sampling methods ii The simulation algorithm is CPU intensive and therefore it is necessary to develop a series of special procedures that will provide an adequate environment to process computationally long tasks There are many quantities that define the initial or environmental conditions for an air s
44. inclusion into the longitudinal compressed files see page 131 this function allows to deter mine if a given observing level was or not marked at the moment of performing the simulations that generated the corresponding compressed file Arguments obslev Input integer The number of observing level If it is out of range the returned value will always be false vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means successful return Returned value Logical true if the level is marked for file recording false otherwise APPENDIX D THE AIRES OBJECT LIBRARY 195 olv2slant FORTRAN call olv2slant nobslev olxv Xv0 zendis zenl zen2 groundz olxs C olv2slant amp nobslev amp olxv 1 amp Xv0 amp zendis amp zenl amp zen2 amp groundz amp olxs 1 Evaluating the slant depths of a set of observing levels The slant depths are calculated along an axis starting at altitude zground for the segment that ends at verti
45. instruction GeomagneticField 32 uT The field strength F will be set to the value indicated in the first parameter while I and D will remain as given by the IGRF model xz plane Gaussian fluctuations either absolute or relative are also supported GeomagneticField 32 uT Fluctuation 500 nT o GeomagneticField On Fluctuation 10 Notice that fluctuations can be introduced with or without overriding the IGRF field components It is also possible to specify 0 1 Relative instead of 10 The next generation of IGRF data will be released after the year 2000 66 CHAPTER 3 STEERING THE SIMULATIONS When magnetic fluctuations are in effect then the magnetic field used for each shower will be different Let Bo be the central value coming from the IGRF model and or entered manually Let AB be the specified fluctuations Notice that in the case of relative fluctuations AB is set using the field strength B AB BoA Bre Then for each new shower two independent Gaussian distributed random numbers AB and AB having mean zero and standard deviation AB 2 are generated and the magnetic field com ponents are set via Bz Bos ABz B Bo AB ot Notice however that the declination angle used for azimuth transformations will always come from the central value that is is not affected by the fluctuations introduced 3 3 5 Statistical sampling control The thinning algorithm described in section 2 3 page 27 mak
46. means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place infield1 Output integer If intype is zero this variable contains the current value of the first integer field of the last scanned record which will be in general a particle code Otherwise it is set to zero rectype Output integer Last scanned record type and return code This argument contains the same information as argument ire of routine getcrorecord Notice that in the case of successful return rectype is equal to intype Returned value Logical True if the last record was successfully read False otherwise End of file or I O error APPENDIX D THE AIRES OBJECT LIBRARY 159 crorecinfo FORTRAN call crorecninfo channel poskey ouflag vrb irc C crorecninfo amp channel amp poskey amp ouflag amp vrb amp irc Printing information about the total number of records within an already opened compressed file The file is scanned starting after the last record already read to count the number of records of each type that were written into it Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile poskey Input integer Positioning key
47. number Default ThinningWFactor 12 s h Thinning weight factor This instruction permits setting the weight factor Wy of equation 2 23 TotalShowers Syntax TotalShowers nofshowers Default None This directive is always required d Total number of showers nofshowers is a positive integer in the range 1 759375 defin ing the number of showers to be simulated in the current task Notice that this is a dynamic parameter that is it can be modified either enlarged or reduced during the simulations 136 APPENDIX B IDL REFERENCE MANUAL Trace Syntax Trace On Off Default Trace is equivalent to Trace On Trace Off is assumed in case of missing specification d Directive to enable or disable input data tracing If enabled On then trace information about the directives being processed by the IDL parser is written into the standard output chan nel This directive is useful to debug IDL input data sets TSSFile Syntax TSSFile On Off Default TSSFile is equivalent to TSSFile On TSSFile Off is assumed in case of missing specification d If TSSFile On is specified then a task summary script file will be generated upon task completion The task summary script file TSS is a plain text file containing information about the main parameters of the simulation in the format Keyword value suitable for processing with other programs Appendix C Output data table index We list here all the tables defined in
48. page 100 The real fields listed in table 4 6 page 91 are defined similarly to the corresponding ground particle record fields with the exception of the x and y coordinates which are defined as follows Coordinates The x y coordinates are the Cartesian coordinates of the point where the particle crossed the level 7 measured from the intersection between the shower axis and the cor responding observing level s surface Time delay Defined as the difference tp where is the particle s absolute time and is the time required for a particle moving along the shower axis at the speed of light to go from the injection point to observing level 7 p The IDL directives RLimsFile ResamplingRatio SaveInFile and SaveNotInFile can be used with longitudinal files to control when a particle must be saved or not The last two directives do not present special difficulties and work as explained in section 3 2 5 page 50 On the other hand the directives RLimsFile lgtpcles fmin Tmax ResamplingRatio s define three parameters Tmin Tmax and sy that are used to determine whether a particle record must be saved or not The rules are the following 1 Let Xe 0 8 X 0 2 Xg where X and X are the vertical injection and ground depths respectively 2 For each observing level i i 1 No let 0 if XM lt x rad RPO i 4 8 a o Aes Tmin if Xe lt Xo lt Xg Tmin if X gt X where x is the vertical depth o
49. particles i thinning level The showers Processed particles were initiated by 101 eV protons with vertical 3 4 5 6 7 8 incidence and BIO Neve log10 Eth Epr located at 1000 g cm The present version of AIRES 2 6 0 can be obtained from the World Wide Web at the following address http www fisica unlp edu ar auger aires AIRES is distributed in the form of a compressed UNIX tar file The installation is automatic for UNIX systems For other operating systems some adaptive work may be needed Appendix A page 109 contains detailed instructions on how to install AIRES and or maintain an existing installation Chapter 2 General characteristics of AIRES The aim of this chapter is to introduce the basic concepts needed to adequately define the problem being considered 2 1 The environment of an air shower 2 1 1 Coordinate system The AIRES coordinate system is a Cartesian system whose origin is placed at sea level at a user specified geographical location The xy plane is located horizontally at sea level and the positive z axis points upwards The x axis points to the local magnetic North that is the local direction of the horizontal component of the geomagnetic field see section 2 1 5 for details The y axis points to the West Figure 2 1 shows an schematic representation of the coordinate system used by AIRES The xy plane is tangent to the sea level surface here taken as a spherical surface of radiu
50. precision injection_depth ground_depth double precision ground_altitude d_ground_inj double precision shower_axis 3 integer Te double precision urandomt Some particle codes AIRES coding system integer pipluscode piminuscode parameter pipluscode 11 piminuscode 11 FIRST EXECUTABLE STATEMENT Starting the AIRES external module interface call speistart shower_number primary_energy default_injection_position injection_depth ground_altitude ground_depth d_ground_inj shower_axis Injecting two particles at the initial injection point and in the direction of the shower axis el primary_energy urandomt 0 05d0 e2 primary_energy el call spaddp0O pipluscode el 1 0 d0 0 d0 1 d0 rc call spaddp0O piminuscode e2 1 0 d0 0 d0 1 d0 1 d0 rc Completing the main program external module interchange The integer argument of routine speiend is an integer return code passed to the calling program 0 means normal return call speiend 0 end Figure 3 3 A sample module for processing special primary particles The purpose of this example is to illustrate the basic structure of a program to process the special primaries the programmed algorithm is not intended to have any validity from the physical point of view 74 CHAPTER 3 STEERING THE SIMULATIONS Figure 3 4 The shower axis injection point coordinate system x y z magenta contrasted with the AIRES coordinate system xyz gr
51. present figures modify the 40 60 zones used in AIRES 2 0 0 or earlier 94 CHAPTER 4 MANAGING AIRES OUTPUT DATA set of levels to be taken into account to save particle records into the compressed file The actions of the instructions that follow are respectively Mark level 1 for recording particles crossing it idem level 4 idem all levels from 10 to 90 in steps of 10 levels unmark level 20 The resulting set of marked levels is 1 4 10 30 40 50 60 70 80 90 4 2 2 Using the AIRES object library The AIRES object library is a set of routines designed with the main purpose of providing adequate tools to analyze the data saved in the compressed output files Appendix D page 144 explains in detail the contents of the library and how to use it In this section some illustrative examples are presented From now on we are going to assume that the AIRES file is being processed by a program provided by the user and similar to the demonstration programs that are included with the AIRES software distributions We are going to use FORTRAN in our examples but this is not a restriction since the AIRES library includes routines for a C interface which allow the C user to fully exploit the library s re sources Output particle codes Every analysis program must begin with a call to routine ciorinit This routines sets up the environ ment where the library routines can work adequately This routine permits setting the particle codi
52. space for it The following list describes the different data items 1 Total number of showers 2 Number of completed showers 3 First shower number 4 9 Reserved for future use 10 Separate showers integer parameter realdata Output double precision array Real data array The calling program must provide enough space for it The following list describes the different data items l Reserved for future use 170 APPENDIX D THE AIRES OBJECT LIBRARY fitghf FORTRAN call fitghf bodata0 eodata0 depths nallch weights ws minnmax nminratio bodataeff eodataeff nmax xmax x0 lambda sqsum irc C fitghf amp bodata0 amp eodata0 amp depths 1 amp nallch 1 amp weights 1 amp ws amp minnmax amp nminratio amp bodataeff amp eodataeff amp nmax amp xmax amp x0 amp lambda amp sqsum amp irc Performing a 4 parameter nonlinear least squares fit to evaluate the parameters Nmax Xmax Xo and A of the Gaisser Hillas function of equation 4 1 The fit is done using the Levenberg Mardquardt algorithm as implemented in the public domain software library Netlib 10 Arguments bodata0 eodata0 Input integer Positive integer parameters defining the number of data points to use in the fit depths Input double precision array eodata0 Depths of the observing levels used in the fit Only the range bodata0 eodata0 is used nallch Input double precision array eodata0 Number of charged
53. tau TT 4 tau Ve 6 nu e De 6 nubar e Vy 7 nu m Dy 7 nubar m Vr 8 nu t Dr 8 nubar t n 10 pid at 11 pi T 11 pi K 12 KOS K 13 KOL kt 14 K K 14 K n 15 eta A 20 lambda A 20 lambdab n 30 n Neutron neutron n 30 nbar AntiNeutron antineutron p 31 p Proton proton 31 pbar AntiProton antiproton SI Table 2 3 AIRES particle codes and names The nuclear coding system and nuclear names are explained in the text 22 Group name and synonyms NoParticles None AllParticles All AllCharged MassiveNeutral Nuclei Hadrons Neutrinos EM e mu tau GPion GChPion GKaon GChKaon nppbar nnbar Nucnucbr CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES Particles in the group Empty group Universal group containing all particles All charged particles including all nuclei All non charged massive particles All nuclei All hadrons All neutrinos and anti neutrinos y eT e7 Table 2 4 AIRES particle groups 2 2 2 Interactions taken into account in the current version of AIRES The processes which are most relevant from the probabilistic point of view are taken into account in AIRES In the current version 2 6 0 the following interactions are included e Electrodynamical processes LPM effect and dielectric suppression Pair production and e e annihilation Bremsstrahlung electrons and positrons Muon bremsstrahlung and muonic pair pro
54. the directive then it can be obtained by means of routine croinputdata0 The directive corresponds to a real input parameter The parameter can be retrieved by means of function getinpreal The directive corresponds to an integer input parameter The parameter can be re trieved by means of function getinpint The directive corresponds to a logical input parameter The parameter can be re trieved by means of function getinpswitch The directive correspond to a string input parameter The parameter can be retrieved by means of routine getinpstring 188 APPENDIX D THE AIRES OBJECT LIBRARY loadumpfile FORTRAN call loadumpfile wdir taskname vrb irc C loadumpfilec amp wdir amp taskname amp vrb amp irc Reading the dump file associated with a given task and copying into internal variables all the information contained within it Arguments wdir Input character string The name of the directory where the file is placed It defaults to the current directory when blank taskname Input character string Task name or dump file name vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is
55. the model being used The directive ExtNucNucMFP allows to disable the call to the external routine and use the built in algorithm for all projectile energies The hadron nucleus nucleus nucleus and or the photon nucleus collisions can be disabled if de sired NuclCollisions Off PhotoNuclear Off These settings are intended to be used only for special purposes The results obtained in such condi tions may be rather unphysical 3 4 2 Other control parameters There are several IDL instructions that allow controlling different parameters and or processes of the simulation algorithms These IDL directives need not be used for normal operation Furthermore the user should take into account that improper settings for some of the parameters associated with these instructions may lead to unphysical results PropagatePrimary Logical switch to control the initial propagation of the primary 70 CHAPTER 3 STEERING THE SIMULATIONS SetTimeAtInjection Logical switch to control whether or not the shower time is set to zero at the injection point The shower clock can be set to zero at the injection point default or at the moment of the first primary interaction GammaRoughCut ElectronRoughCut Threshold energies for normal propagation of gammas and electrons respectively Particles with kinetic energies below those thresholds are roughly propagated that is many processes are calculated only approximately or are ignored
56. this record does not depend on the compile time option selected for the particle record CHAPTER 4 MANAGING AIRES OUTPUT DATA 89 Field Name Short Normal Long Integer 1 1 1 Particle code Real 1 1 1 Energy GeV log 2 2 2 Distance from the core m log 3 3 3 Ground plane polar angle radians 4 4 Direction of motion x component 5 5 Direction of motion y component 4 6 6 Arrival time delay ns 5 7 7 Particle weight 8 Particle creation depth g cm2 9 Last hadronic interaction depth g cm2 Table 4 5 Fields contained in the particle records of compressed ground particle files The field numbers for the different particle records selectable at compilation time see text named short normal and long records are tabulated Notice that a given field can have different field numbers Arrival time The saved quantity is the arrival time delay t to where t is the absolute time mea sured from the beginning of the shower and to is the global time shift described in table 4 1 page 85 Particle weight The statistical weight of the particle see section 2 3 Creation depth The vertical atmospheric depth of the point where the particle was inserted into the simulating program s stacks Last hadronic depth The vertical atmospheric depth corresponding to the last hadronic interaction suffered by the particle or by one of its ancestors For each one of these quantities a corresponding record field is defined The
57. three integers year month day or a floating point number with the format year part_of_the_year DelGlobal Syntax DelGlobal var d Deletes an already defined global variable See also directives Import and SetGlobal 118 APPENDIX B IDL REFERENCE MANUAL DielectricSuppression Syntax DielectricSuppression On Off Default DielectricSuppression is equivalent to DielectricSuppression On DielectricSuppression On is assumed in case of missing specification s h Switch to include exclude the dielectric suppression effect from the LPM algorithms 19 25 for the case of electron or positron bremsstrahlung The effect is enabled by default Disabling it may lead to non realistic air shower simulations If LPMEffect Off is in effect see page 125 then the dielectric suppression is always disabled This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES DumpFile Syntax DumpFile Reserved for future use ElectronCutEnergy Syntax ElectronCutEnergy energy Default ElectronCutEnergy 80 Kev s Minimum kinetic energy for electrons and positrons Every electron having a kinetic en ergy below this threshold is not taken into account in the simulation positrons are forced to annihilation energy must be greater than or equal to 80 keV ElectronRoughCut Syntax ElectronRoughCut energy Default ElectronRoughCut 900 Kev s Electrons and p
58. to raw data recorded at the ground surface while the lower ones are projections onto the shower front plane using a special algorithm that takes into account the shower attenuation 27 In the upper graphs the positive x axis is directed towards the arrival direction The arrows represent the projection of the magnetic field onto the shower front plane The data corresponds to a single 3 x 10 eV proton shower with a zenith angle of 70 degrees The environmental parameters correspond to the El Nihuil site located in Argentina see table 3 2 but using an artificially large 70 uT vertical magnetic field The simulations were done with a 1078 thinning level and W 20 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 43 1500 10 2 1500 ss D 1000 1000 500 500 10 0 0 500 500 1000 1 1000 1500 1500 1000 0 1000 1000 0 1000 1500 2 1500 x fag 1000 1000 500 500 0 0 500 500 1000 1000 1500 1500 1000 0 1000 1000 0 1000 x m X m Figure 2 20 Lateral distributions of positive and negative muons represented as 2D false color plots The upper graphs correspond to raw data recorded at the ground surface while the lower ones are projections onto the shower front plane using a special algorithm that takes into account the shower attenuation 27 In the upper graphs the positive x axis is directed towards the arrival direction The arrows in the upper lower graphs represent the projection of the magnetic fie
59. used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments mvnew Input integer Macro version number Must be an integer in the range 1 759375 If mvnew is zero then the macro version is not set mvold Output integer Macro version number effective at the moment of invoking the rou tine This variable will be set to zero in the first call to speimv APPENDIX D THE AIRES OBJECT LIBRARY 207 spinjpoint FORTRAN call spinjpoint csys x0 y0 z0 tsw tObeta irc C spinjpoint amp csys amp x0 amp y0 amp z0 amp tsw amp tObeta amp irc Setting the current injection point for primary particles This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments csys Input integer Parameter labeling the coordinate system used csys 0 selects the AIRES coordinate system csys 1 selects the shower axis injection point system de fined in section 3 5 x0 y0 z0 Input double precision Coordinates of the injection point with respect to the chosen coordinate system in meters tsw Input integer Injection time switch If tsw is zero then t0beta is an absolute injection time if tsw is 1 then the injection time is set as the time employed by a particle whose speed is tObeta x c to go from the original injection point to the intersection point of the show
60. x axis zero azimuth axis corresponds to the local magnetic north If desired it is possible to specify geographic azimuths PrimaryAzimAngle 37 2 deg 39 5 deg Geographic In the preceding directive the Geographic keyword indicates that the origin of the azimuth angles is the direction of the local geographic north It is worthwhile mentioning that this does not alter the axis definitions of section 2 1 1 when geographic azimuths are in effect the azimuth with respect to the AIRES coordinate system is evaluated via D geographic 3 8 The sine distribution is sometimes called cosine distribution relating it with the accumulative probability function of sie Hh gay cas the sine distribution Fyine O JS A Psine u du CHAPTER 3 STEERING THE SIMULATIONS 63 where D is the geomagnetic declination angle defined in section 2 1 5 page 19 Notice that positive geographic azimuths indicate eastwards directions For a complete description of this directive see page 129 Position of injection ground and observing levels The directives InjectionAltitude or its synonym InjectionDepth GroundAltitude or its syn onym GroundDepth and ObservingLevels permit controlling the position of the injection point the ground surface and the different observing levels respectively All the altitude specifications refer to vertical altitudes noted as z in figure 2 1 page 12 and can be expressed either as lengths above sea level or
61. zero rectype Output integer Record type and return code This argument contains the same information as argument ire of routine getcrorecord Returned value Logical True if a record was successfully read False otherwise End of file or I O error APPENDIX D THE AIRES OBJECT LIBRARY 175 getglobal FORTRAN call getglobal gvname sdynsw gvval valen C getglobalc amp gvname amp sdynsw amp gvval amp valen Getting the current value of an already defined global varible When this routine is used to re trieve information stored in a compressed file the data returned correspond to the most recently opened compressed file Arguments gvname Input string Name of global variable sdynsw Output integer Type of variable 1 dynamic 2 static 0 if the variable is undefined gvval Output string The string currently assigned to the variable The calling program must ensure enough space to store the string valen Output integer Length of gvval valen is negative for undefined variables 176 APPENDIX D THE AIRES OBJECT LIBRARY getinpint FORTRAN value getinpint dirname C value getinpintc amp dirname Getting the current value for an integer static input parameter corresponding to the most recently opened compressed file This routine is used to get from the current file s header those integer input parameters not returned by routine croinputdata0 see page 154 Arguments dirname Input s
62. 00 CHAPTER 4 MANAGING AIRES OUTPUT DATA 83 By default AIRES does not create any task summary script file The directive TSSFile must be used to enable this feature 4 2 Processing compressed particle data files Like other simulation systems 1 30 AIRES can produce output files containing detailed infor mation about the particles generated during the simulations The well known fact that that detailed information generates huge amounts of data has been especially taken into account in the design of AIRES which includes an ad hoc data compressing algorithm to save file space A detailed explanation of the compressing algorithm a rather technical matter is beyond the scope of this manual We shall limit ourselves to briefly list its main characteristics Format The compressed files are plain text files that can be generated in any computer and copied and processed in any other one This is valid even if the machines do not have the same oper ating system and or do not use the same character codes for example non ASCII machines Organization The files contain a header with data related to its structure and the conditions of the simulation The particle data section represents the bulk of the file and in general the records corresponding to any one of the simulated showers are delimited by beginning of shower and end of shower records There is practically no limit in the number of showers that can be included in a si
63. 11 11 13 17 18 19 20 20 22 23 27 27 28 29 30 36 viii 3 2 4 Physical units aoaaa a 325 CAN VINO OM es acn sane we ee woe E ae R E E 3 3 More on IDL directives aoaaa 3 3 1 Runcontrol sa s ae eae eee a a a eee a 3 3 2 File directories used by AIRES 3 3 3 Defining the initial conditions 3 3 4 Geomagnetic field aoaaa 3 3 5 Statistical sampling control 3 3 6 Output table parameters 3 3 7 Random number generator 3 4 Input parameters for the interaction models 3 4 1 External packages 0000 3 4 2 Other control parameters 3 5 Special primary particles o oo 0 3 5 1 Defining special particles 3 5 2 The external executable modules Managing AIRES output data 4 1 Using the summary program AiresSry 4 1 1 The summary tile 2245 24464 246s os 2442 44 4 1 2 Exporting data x0 2640 2 6 See S265 eGo aed 4 1 3 The task summary script file 4 2 Processing compressed particle datafiles 4 2 1 Customizing the compressed files 4 2 2 Using the AIRES object library The AIRES Runner System 5 1 Checking input files 2 ss aoaaa eee He ee eee 5 2 Managing simulation tasks 0 5 2 1 Canceling tasks and or stopping the simulations 5 2 2 Performing custom operations be
64. 5 Vertical atmospheric depth for altitudes larger thanl1Okm 16 Hadronic mean free paths 2 eee 25 Effect of the thinning on the longitudinal development of charged particles 31 Effect of the thinning on the ete lateral distribution 32 Effect of the thinning on the u u7 lateral distribution 33 AIRES thinning algorithm and et e7 lateral distribution 34 AIRES thinning algorithm and weight distributions 35 AIRES thinning algorithm Processor time requirements 35 Longitudinal development of 3 x 107 eV proton showers 37 Energy longitudinal development of 3 x 10 eV proton showers 37 Lateral distributions for a single 1078 thinning level shower 38 Energy distributions for a single 1078 thinning level shower 39 Mean arrival time distributions for 1020 5 eV showers 2 2 2 0 0005 40 Lateral distributions of gammas electrons and muons for inclined showers 41 jst and u lateral distributions for inclined showers I 42 jt and u lateral distributions for inclined showers ID 43 Sample AIRES input 2 2 2 20 0000000000 2 eee 51 Sample AIRES terminal output 2 2 ee 55 A module for special primary particles 000 0004 73 Shower axis injection point coordinate system o oo 74 Sample AIRES TSS file 2 0 0 0
65. 6 57 58 59 60 6l 62 63 64 65 66 Code 1307 1308 1311 1312 1313 1314 1321 1322 1323 1341 1391 1392 1405 1407 1411 1413 1491 1492 1493 1501 1505 1506 1507 1508 1511 1512 1513 1514 1521 1522 1523 1541 1591 1592 1705 1707 1711 1713 1791 1792 1793 APPENDIX C OUTPUT DATA TABLE INDEX Table name Gaga Geeqcqeqeeqceqcaeac nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development nweighted longit development Muons Muons Pions Pions Kaons Kaons Neutrons Protons Antiprotons Nuclei Other charged pcles Other neutral pcles e and e mu and mu pit and pi K and K All charged particles All neutral particles All particles Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longi
66. 66 7 10571 7 11887 9 25919 3 59367 2 36479 9 oe Table 2 2 Total shower axis length m and slant path g cm measured from the top of the atmosphere 110 km a s l down to sea level tabulated versus the zenith angle To precisely estimate X z we have evaluated numerically the integral of equation 2 8 for various representative cases In table 2 2 the results corresponding to zg 0 ground level located at sea level are tabulated for different zenith angles The top of the atmosphere is located at an altitude of 110 km a s l and Linsley s parameterization is used in the calculations The respective data corresponding to the plane Earth model are also tabulated for comparison purposes The tabulated quantities indicate that the plane and curved Earth estimations differ in less than 4 for all zenith angles lt 80 and the differences increase notably as long as the zenith angle approaches 90 The geometrical length of the shower axis a is also tabulated for both models In the plane Earth approximation this length is given by eee s 2 10 i cos O where Zmax is the vertical altitude of the top of the atmosphere 110 km in the present case On the other hand if the Earth s curvature is taken into account the expression for a becomes a y Re Zvmax 2 Re zg sin O Re zg cos O 2 11 where Zymax Stands for the vertical altitude of the injection point 110 km Equation 2 10 is the Re
67. 86 118 122 125 127 time distributions 27 39 141 TSS or tss see task summary script file unweighted distributions 28 137 139 140 urandon see AIRES object library urandomt see AIRES object library US standard atmosphere 13 14 17 116 vertical atmospheric depth see atmospheric depth vertical Xmax 27 78 128 141 xslant see AIRES object library 236 NOTES NOTES 237 238 NOTES
68. 94 223 225 227 particle codes 94 146 MOCCA SP 3 multiple primaries see special primary particles muon bremsstrahlung v 3 4 22 70 127 217 221 muonic pair production 4 70 127 215 217 221 Netlib 3 79 170 Nmax 78 141 nuclcode see AIRES object library nucldecode see AIRES object library nucleus nucleus collisions 4 68 120 126 220 olcoord see AIRES object library olcrossed see AIRES object library olcrossedu see AIRES object library olsavemarked see AIRES object library olv2slant see AIRES object library online help 48 INDEX opencrofile see AIRES object library output data tables 54 66 106 137 219 221 224 226 pair production v 3 4 22 122 particle codes 20 94 95 146 155 photoelectric effect v 3 4 22 photonuclear reactions v 3 4 23 129 portable dump file see internal dump file portable format positron annihilation v 3 4 22 24 118 217 pre showers 71 primary energy spectrum 61 129 process definition 45 QGSIJET v 3 4 23 25 54 68 102 111 120 122 126 216 220 222 223 226 random number generator 27 67 74 100 131 186 197 213 224 elementary without seed 67 148 raninit see AIRES object library recompiling simulation programs 112 regetcrorecord see AIRES object library release notes 215 resampling algorithm 86 90 132 222 rewinding compressed files 100 162 run definition 45 shower axis injection p
69. AIRES A system for air shower simulations User s guide and reference manual Version 2 6 0 S J Sciutto Departamento de Fisica Universidad Nacional de La Plata C C 67 1900 La Plata Argentina sciutto fisica unlp edu ar July 11 2002 R shower Extended Simulations A AIRES user s guide and reference manual Version 2 6 0 2002 S J Sciutto La Plata Argentina This manual is part of the AIRES 2 6 0 distribution The AIRES system is distributed worldwide as free software for all scientists working in educational research non profit institutions Users from commercial or non educational institutions must obtain the author s written permission be fore using the software and or its related documentation The present document makes obsolete all the previous versions of the AIRES user s manual and reference guide NO WARRANTY The AIRES system is provided in an as is basis without warranty of any kind either expressed or implied including but not limited to the implied warranties of mer chantability and fitness for a particular purpose The entire risk as to the quality and performance of the program is with the user Should the program prove defective the user assumes the cost of all necessary servicing repair or correction In no event will the AIRES author s be liable to any user for damages including any general special incidental or consequential damages arising out of the use or inabi
70. Appendix D The AIRES object library The AIRES object library is a collection of modules that are useful in several applications including but not limited to special primary modules see section 3 5 and output file processing particularly compressed files generated by the AIRES compressed i o unit CIO Most of the routines were es pecially written for these purposes but some of them are of general nature and are also used by the simulation and or summary programs D 1 C interface The modules of the AIRES object library are callable from a C program In general the calling state ment is similar to the FORTRAN one taking into account that all arguments are passed by reference That means that the actual arguments must be pointers to the corresponding data items This requirement is made evident when describing the different routines by placing an ampersand amp before the corresponding arguments The experienced C programmer will understand however that this character is not required in actual calling statements containing pointer variables as argu ments The following example illustrates this point int channel vrb irc int recnumber int crogotorec if crogotorec channel amp recnumber vrb irc All the arguments of crogotorec are defined as pointers except reenumber which is declared as an integer variable The amp placed before this argument ensures that this variable be passed by reference to the called r
71. ECT LIBRARY error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means that a record with zero default record type was successfully read 2 gt 0 means that an alternative record of type 7 was successfully read 1 means that an end of file condition was got from the corresponding file Any other value indicates a reading error ire equals the system return code plus 10000 Returned value Logical True if a record was successfully read False otherwise End of file or I O error APPENDIX D THE AIRES OBJECT LIBRARY 183 ghfpars FORTRAN call ghfpars nmax xmax x0 lambda vrb irc C ghfpars amp nmax amp xmax amp x0 amp lambda amp vrb amp irc Setting the internal quantities needed to work with the Gaisser Hillas function equation 4 1 related routines Arguments nmax Input double precision Parameter Nmax of equation 4 1 xmax Input double precision Parameter Xmax of equation 4 1 x0 Input double precision Parameter Xo of equation 4 1 lambda Input double precision Parameter of equation 4 1 irc Output integer Return code 0 means successful return vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is po
72. ES 1 2 0 files etc The name Aires can be changed modifying adequately the config file If this name was changed then the user supplied name must be typed in place of the default one You should also obtain a similar output if you invoke the AIRES QGSJET simulation program AiresQ instead of Aires 112 APPENDIX A INSTALLING AIRES AND MAINTAINING EXISTING INSTALLATIONS A 2 Recompiling the simulation programs In many cases it may be necessary to recompile the simulation programs after having successfully installed the AIRES system Some examples of such situations are e Some compilation parameters were not set accordingly with the user needs or the required configuration is no more the one set up at the moment of installing the software e It is necessary to install AIRES in different not compatible platforms sharing the same direc tory tree e It is necessary to create more than one executable program each one compiled with different compilation parameters As an example of this case consider that the number and kind of records that are written in the compressed particle files can be controlled by means of compila tion parameters see section 4 2 1 and that it is required to have the executables for different file formats The arguments recognized by the doinstall executable script allow the user to easily perform the different operation required in cases like the ones previously enumerated The general syntax of doinstall is
73. IRES OUTPUT DATA program sample integer datype irc icode idist inear integer indata 30 double precision fldata 30 integer particlecode double precision logdistance numberofnear call ciorinit 0 1 0 are call opencrofile mydir myfile 0 10 4 channel crofieldindex channel 0 Particle code 4 datype irc crofieldindex channel 0 Distance from the core 4 datype irc 99 ire crofieldindex channel 2 Particles too near 4 datype irc okflag getcrorecord channel indata fldata altrec 0 irc if irc eq 0 then particlecode indata icode logdistance fldata idist else if irc eq 2 then numberofnear fldata inear end if Figure 4 2 Processing compressed data files an example illustrating how to set field indices automatically 100 CHAPTER 4 MANAGING AIRES OUTPUT DATA Repositioning Routine crorewind repositions an already opened file at the beginning of the data section Routines crorecnumber and crogotorec used jointly permit accessing the data records in arbitrary order Fast scanning of a file Routine crorecfind finds the next appearance of a record of a given type to locate shower headers for example getcrorectype returns the type of the next record and regetcrorecord re reads the current record Longitudinal tracking file utilities Routine crooldata returns basic information about the positions of the observing levels d
74. IRES version 10 means that the file could be opened normally but that it seems not to be a valid AIRES compressed data file or is a corrupted file 12 invalid file header 14 not enough size in some of the internal arrays 16 format incompatibilities 20 too many compressed files already opened 300 lt ire lt 400 indicates a version incompatibility when processing files written with other AIRES version or invalid version field corrupt header Any other value indicates an opening header reading error ire equals the system return code plus 10000 APPENDIX D THE AIRES OBJECT LIBRARY 197 raninit FORTRAN call raninit seed C raninit amp seed Initialization of the uniform pseudo random number generator This routine must be called before the first invocation of grandom urandom or urandomt Arguments seed Input double precision Seed to initialize the random series If seed does not belong to the interval 0 1 then the seed actually used for initialization is internally generated using the elementary generator clockrandom 198 APPENDIX D THE AIRES OBJECT LIBRARY regetcrorecord FORTRAN okflag regetcrorecord channel intfields realfields altrec vrb irc C okflag regetcrorecord amp channel amp intfields 1 amp realfields 1 amp altrec amp vrb amp irc Re reading the current record The input and output parameters of this routine are equivalent to the respective arguments of routine getcro
75. Pj The fact that the statistical weights are set with the inverse of the acceptance probabilities ensures an unbiased sampling that is all the averages evaluated using the weighted particles will not depend on the thinning energy and will be identical to the exact ones obtained for Ei 0 Only the fluctuations are affected by the thinning level If Fin is close to the primary energy then the thinning process begins early in the shower development and a low number of samples is obtained with relatively large and fluctuating weights On the other hand low thinning energies lead to larger samples with less statistical fluctuations Processing large samples demands more computer time so lowering the thinning level makes the simulation more expensive from the computational point of view 2 3 2 AIRES extended thinning algorithm The thinning algorithm of AIRES 2 6 0 includes an additional feature which has proved to be helpful to diminish statistical weight fluctuations in many cases This extended algorithm was designed to ensure that all the statistical weights are never larger that a certain positive number W gt 1 specified as an external parameter The mechanics of the AIRES extended algorithm can be summarized as follows Let w be the weight of particle A and W lt W 2 be an additional internal positive number Consider the number of secondaries in the process 2 20 e Ifn lt 3 then If w4 gt Wy or wa Ea min Epg
76. RES installations this file is placed in the user s home directory 5 1 Checking input files In section 3 2 2 page 46 the IDL directives CheckOnly and Trace were used to instruct AIRES simulation programs to scan a given input file report on its contents and stop without actually starting the simulations The ARS command airescheck t myfile inp There may be some incompatibilities when running ARS commands in clusters employing afs file systems 101 102 CHAPTER 5 THE AIRES RUNNER SYSTEM will invoke Aires with the same input as displayed in page 47 The t qualifier is placed to enable typing the input lines as long as they are scanned There are additional qualifiers accepted by this command for example airescheck tP p AiresQ myfile inp The p qualifier overrides the default simulation program used to process the input file and the P switch indicates that the output must be printed instead of being typed at the terminal The print command to use can be set modifying the airesre initializing file 5 2 Managing simulation tasks Once the input file has been checked the simulations can be started The command airestask myfile will first check that file myfile inp exists and then will create an entry in the corresponding ARS spool Finally aireslaunch will be executed The aireslaunch script will detect that there is a task pending completion and so will prompt the user to start the simulations In ca
77. RandomSeed GetFrom otheridfile extracts the seed used in the task that created the IDF file otheridfile and uses it to initialize the generator 3 4 Input parameters for the interaction models The expression interaction models identifies a series of subroutines and functions that contain the actual implementations of the algorithms that control the propagation of particles Such algorithms emulate the physical rules associated with the different interactions that take place in an air shower As it is well known there are still many open problems in this area and therefore the interaction models cannot be considered a crystallized part of the simulation programs Furthermore in the design of the interaction models and external packages units shown in figure 1 1 page 7 every effort was made to make them easily replaceable in order to be able to incorporate improved code to be developed in the future The IDL directives that are going to be mentioned in this section allow the user to control different model parameters Such directives are defined from within the interaction model section and for the reasons explained in the preceding paragraph they are of a changing nature For AIRES versions later than the current version 2 6 0 the model related directives may no longer be supported be replaced by alternative ones or their syntax be totally or partially changed 3 4 1 External packages Both SIBYLL 6 and QGSJET 7 hadronic collisions pa
78. S Runner System focused on improving the capacity of the System to cope with large scale computations 8 The AIRES runner scripts now support the inclusion of a BeforeProcess macro 220 APPENDIX F AIRES HISTORY 221 10 11 New modules added to the AIRES object library in particular some routines for easier process ing of longitudinal particle tracking files Revision of the user s manual and inclusion of several issues that were introduced at the previ ous release of AIRES with pending documentation Additionally several minor changes improvements and of course corrections of bugs AIRES version 2 4 0 19 Oct 2001 This version of AIRES consists of about 620 routines adding up to more than 88 000 lines of source code Features 10 11 12 13 New version of the splitting algorithm used to process low energy hadronic interactions This new version was tuned to effectively emulate well known interaction models Low energy cross sections are now evaluated using fits to experimental data Improved procedures for y nucleus collisions Muon propagation now takes into account muon bremsstrahlung and muonic pair production The new algorithms are based in the theory by Kokoulin and Petrukhin 18 New improved procedure to treat knock on electrons generated by heavy charged particles Full propagation of A baryons Improved procedures for meson and baryon decay Exhaustive re
79. TER 5 THE AIRES RUNNER SYSTEM 107 Its action is to invoke the AIRES summary program with the following input Summary O TaskName mytask ExportTable 1001 ExportTables 1205 1213 End generating text files for tables 1001 1205 1207 1211 and 1213 see appendix C In some cases it may be necessary to specify other parameters like in the following example airesexport w idfdir O LM s mytask 2501 This command will generate single shower tables enabled by the s qualifier as well as average ones The options LM correspond to dN dlog E distributions with energies expressed in MeV see section 4 1 2 and the string following the w qualifier idfdir indicates the directory where the IDF and or ADF files are located The global directory accordingly with the definitions of section 3 3 2 5 4 1 Converting IDF binary files to ADF portable format ADF files were implemented for AIRES version 2 0 0 and to have them written by the simulation programs after a task is completed it is necessary to explicitly enable them by means of the IDL directive ADFile The binary IDF is always generated regardless of the input settings and or the version of AIRES used Of course the IDF stores all the data associated with both input parameters and output observ ables and is enough for any kind of analysis provided the user always works with compatible com puters But this may not be the case when a person or group is working at diffe
80. TIONS The CheckOnly directive instructs AIRES to normally read and check the input data and then stop without actually starting any simulations The input lines placed after the Trace statement are echoed to the terminal and the Input directives allows including IDL directives placed in other files Notice the format used for directive echoing It includes the line number as well as the file nesting level starting by zero for the standard input channel Input directives can be nested and permit splitting the input data into separate files This is most useful for organizing a set of input files including some common directives in a single shared file included by every particular file etc In UNIX environments it is possible to use one of the scripts of the AIRES Runner System to automatically check a given input file For details see chapter 5 page 101 3 2 3 Obtaining online help The AIRES simulation and or summary programs accept instructions that permit obtaining informa tion about AIRES IDL instructions The information that can be retrieved in this way is not extensive but it can be useful to the experienced user as a quick guide Invoking AIRES interactively and typing will return a list of the names of the IDL directives 2 will cause the list to include also the hidden directives The prompt Aires IDL gt typed at the terminal indicates that AIRES understands that this session is interactive The Help command is simil
81. This parameter allows to control the file positioning after returning from this routine If zero or negative the file remains positioned at the end of file point if 1 at the beginning of data and if greater than 1 at the position found before the call This last option may eventually imply a significant increase in processing time for very large files ouflag Integer input Logical output unit s selection flag See routine croheaderinfo vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means successful return 160 APPENDIX D THE AIRES OBJECT LIBRARY crorecnumber FORTRAN recno crorecnumber channel vrb irc C recno crorecnumber amp channel amp vrb amp irc This function returns the current record number corresponding to an already opened com pressed file Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine open
82. V 1073 eV and must be greater than all the cut energies Both SIBYLL and Bartol MFP s are now enabled by default The old defaults were SIBYLL On and Bartol Off The AIRES object library was substantially enlarged with new routines callable from analysis programs This includes also interface routines to permit processing compressed files from a C environment Corrected minor bug in input data summary primary energy printing Corrected minor bug in rounding algorithm used in floating point numbers encoding routines Fixed bug in the algorithm for counting particles during the longitudinal development of the shower The bug affected particle numbers in runs with very high energy thresholds 1 GeV or so Many thanks to Ricardo Vazquez University of Sao Paulo Brazil Fixed bug in the algorithm to set the depth of first interaction for showers with electron pri maries Many thanks to Pierre Billoir LPNHE Paris France Fixed bug in the All neutral particles tables calculations Many thanks to Ivone Albuquerque U of Chicago USA te a Task names with underscores can now be properly processed using the LaTeX option Problem pointed out by Pierre Billoir Added LPM effect On Off switch Geomagnetic field included The geomagnetic field can be specified either explicitly given the modulus and orientation of B or implicitly indicating the geographical coordinates and altitude of the site in
83. a new process in other words the input file will be scanned every two CPU hours allowing for eventual changes in the dynamical parameters of the simulations RunsPerProcess 4 ShowersPerRun 5 Here the maximum CPU time is not set indicating that there will be no time limit for a run to com plete Instead every run will finish after concluding the simulations of five showers The processes will end when four runs are completed The three directives can also be used simultaneously RunsPerProcess 2 ShowersPerRun 2 MaxCpuTimePerRun 6 hr This also includes all the variables that were explicitly set by means of the corresponding IDL instructions CHAPTER 3 STEERING THE SIMULATIONS 59 These instructions indicate that a run will finish after six processing hours or after completing two showers what happens first The run control directives like any other dynamic directive can be modified during the simu lations if needed The changes will be effective after a new process is started see section 3 1 Let us assume that a certain task is started with the control parameters of the previous example After a while it is decided that the maximum cpu time per run is too high and that there is no need to limit the number of showers per run The input file is thus modified i The MaxCpuTimePerRun line is replaced by MaxCpuTimePerRun 3 hr ii The ShowersPerRun line is deleted After finishing the current process with the old settings thi
84. a very long list of persons indeed either to report a bug or to make a comment on the program La Plata July 2002 Contents Summary 1 1 2 1 2 2 2 3 3 1 Introduction Structure of the main simulation programs 00004 1 2 Computer requirements 0 000000222 eee 1 3 Getting and installing AIRES 2 22 002 General characteristics of AIRES The environment of an airshower 0 000 eee eee ee 2 1 1 2 1 2 2 1 3 2 1 4 2 1 5 Coordinate system o oo Atmosphere lt lt aaao aaa ESS RGSS The slant depth and the Earth s curvature oaoa aaa Range of validity of the plane Earth approximation Geomagnetic field ooo 00 ee ee Air showers and particle physics ooa a 2 2 1 2 2 2 2 2 3 2 2 4 Particle codes 1 a Interactions taken into account in the current version of AIRES Processing the interactions 2 020585 Random number generator 02 20 022 ee eee Statistical sampling of particles The thinning algorithm 2 3 1 Steering the simulations Tasks processes and runs 0 0000 eee eee eee 3 2 The Input Directive Language IDL 2 0 3 2 1 3 2 2 3 2 3 A first example 6k hia e ede eee bee ee og eee ee eA Errors and input checking 0 000 eee eee Obtaining online help 2 2 2 2 2 2 2202 vii oo un
85. account in the simulation energy must be greater than or equal to 80 keV GammaRoughCut Syntax GammaRoughCut energy Default GammaRoughCut 750 Kev s Gamma rays are not followed using detailed calculations when their energy is below the one specified by means of this directive This means that several processes are not taken into account for example pair production energy must be greater than or equal to 45 keV This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES APPENDIX B IDL REFERENCE MANUAL 123 GeomagneticField Syntax GeomagneticField On Off GeomagneticField stg inc dec Eluctuations fluc GeomagneticField On Fluctuations fluc Default GeomagneticField Off when there is no Site specification GeomagneticField On otherwise s Setting the geomagnetic field manually and or enabling magnetic fluctuations stg must be a valid magnetic field strength specification and inc and dec are angle specifications Such fields correspond respectively to the geomagnetic field strength F and to the inclination I and declination D angles defined in section 2 1 5 page 19 When one or more of such parameters are entered by means of the GeomagneticField directive they override the respective values that are calculated automatically using the IGRF model 8 as explained in section 3 3 4 page 64 The fluctuation specification fluc adopts three dif
86. ains plots of the mean free paths corresponding to proton nucleus pion nucleus kaon nucleus and Fe nucleus collisions plotted as a function of the projectile energy All the alterna tive sets of mean free paths available in AIRES are displayed Selecting the particle s fate For each interaction i A represents the mean path expressed in quantity of matter that is g cm the particle should move before actually suffering the interaction To evaluate the actual path to a given interaction it is necessary to sample the corresponding exponential probability distribution Pip A exp p A Let pj i 1 n the set of values obtained after sampling the corresponding distributions for all the possible interactions The interaction the particle will actually undergo also called the fate of the particle is then selected It is the interaction j corresponding to the minimum of the p s that is p lt p for all 7 Moving the particle and processing the selected interaction After the particle s fate has been decided the corresponding interaction begins to be processed First the particle must be advanced the path indicated by p It is necessary to convert the path in a geomet rical distance and this depends on the atmospheric model and the particle s current position In the case of charged particles the advancing procedure also takes care of the ionization energy losses the scattering and the geomagnetic field deflect
87. allations As mentioned in section 1 3 page 9 every AIRES distribution is currently packed in a single com pressed UNIX tar file In this appendix it is assumed that the software distribution was successfully decompressed and tar expanded A 1 Installing AIRES 2 6 0 In UNIX platforms the installing procedure is quite simple Almost everything is done automatically The key points to take into account are a A Unix shell script doinstall is provided This script will install the software automatically b The file config contains all the customizable variables You must edit it before invoking doin stall c There will be two main directories 1 Installation root directory hereinafter named Iroot which is the directory where the distribution file was downloaded that is the directory containing the doinstall script 2 Aires root directory hereinafter named Aroot which is the highest level directory for the installed files You will need to specify Aroot For standard personal installation the default creating a directory named aires in your home directory will be OK Notice that the Iroot and Aroot directories may or may not be the same directory Do not worry about this The installation program will manage every case properly d Your account must have access to a FORTRAN 77 compiler normally commands f77 or fort77 and in some cases to a C compiler commands ce gec etc and these compilers must be placed
88. ally for those quantities whose validity ranges may span many orders of magnitude In such cases a number of commonly used multiples or sub multiples of the fundamental unit are surely available The complete list of units currently implemented is displayed in table 3 1 CHAPTER 3 STEERING THE SIMULATIONS 49 Angle deg 1 deg ad 180 7 deg Atmospheric depth g om2 1 g cm Energy ev 107 GeV kev 1076 GeV Mev 10 3 GeV GeV 1 GeV TeV 108 GeV PeV 10 GeV EeV 10 GeV Zev 10 GeV Yev 1015 GeV 6 24 x 109 GeV Length i 0 0254 m 12 in 3ft i 5280 ft Magnetic Field Table 3 1 Physical units accepted within IDL directives The underlined keywords indicate the units used internally to store the corresponding quantities The magnetic field unit T Gs stands for the SI cgs unit Tesla Gauss while gm corresponds to y 1 y 1 nT Time specifications using hr min and or sec may consist in the combination of more that one field like in 3 hr 30 min for example 50 CHAPTER 3 STEERING THE SIMULATIONS 3 2 5 Carrying on In figure 3 1 a second example of an IDL input data set is displayed Notice first that IDL instructions can be commented All the characters following a character are ignored The Skip statement is also useful to place comments and or introduce plain text in the input files with no need of single line comment characters as well as to skip a part of the directives without deleting the lines
89. annot be detected directly it is necessary instead to measure the products of the atmospheric cascades of particles initiated by the incident astroparticle An atmospheric particle shower begins when the primary cosmic particle interacts with the Earth s atmosphere This is in general an inelastic nuclear collision that generates a number of secondary particles Those particles continue interacting and generating more secondary particles which in turn interact again similarly as their predecessors This multiplication process continues until a maximum is reached Then the shower attenuates as far as more and more particles fall below the threshold for further particle production A detailed knowledge of the physics involved is thus necessary to interpret adequately the mea sured observables and be able to infer the properties of the primary particles This is a complex problem involving many aspects Interactions of high energy particles properties of the atmosphere and the geomagnetic field etc Computer simulation is one of the most convenient tools to quantita tively analyze such particle showers In the case of air showers initiated by ultra high energy astroparticles gt 10 eV the primary particles have energies that are several orders of magnitude larger than the maximum energies attain able in experimental colliders This means that the models used to rule the behavior of such energetic particles must necessarily make extrapolation
90. ans successful return APPENDIX D THE AIRES OBJECT LIBRARY 163 crospcode FORTRAN isspecial crospcode pcode splabel C isspecial crospcode amp pcode amp splabel This logical function determines whether or not a given particle code corresponds to a special primary particle Arguments pcode Input integer The particle code to check splabel Output integer Label associated to the special particle or zero if the code does not corresponds to a special particle This variable is useful for further use with other library routines and should not be set by the calling program Returned value Logical True if the input code corresponds to a special primary particle False otherwise 164 APPENDIX D THE AIRES OBJECT LIBRARY crospmodinfo FORTRAN call crospmodinfo spname spmodu spml sppars sppl irc C crospmodinfoc amp spname amp spmodu amp spml amp sppars amp sppl amp irc Retrieving information about the external module associated to a already defined special par ticle When this routine is used to retrieve information stored in a compressed file the data returned correspond to the most recently opened compressed file Arguments intdata Input string The name of the special particle spmodu Output string The name of the associated module The calling program must provide enough space for this string spmodu Output integer Length of string spmodu sppars Output string Stri
91. ar to but it will maintain prompting disabled During an interactive session it is always possible to enable or disabling the prompt by means of the directive Prompt There are two other kinds of help that can be obtained using the current AIRES version namely tables and sites which display the list of available output data tables see section 4 1 and or appendix C and the currently defined geographical sites see section 3 3 4 respectively The directive Exit which can be abbreviated as x will cause AIRES to stop immediately without any further action not even completing the IDL instruction scanning phase and is useful to end interactive help sessions 3 2 4 Physical units There are many IDL directives which include one or more specifications corresponding to physical quantities In most cases these specifications have the format number unit like in the Prima ryEnergy specification of section 3 2 1 for instance Number and unit are character strings the first one indicates the decimal numerical value for the quantity being specified while unit repre sents the unit in which number is expressed The characters used for the unit field resemble the name assigned in the real world to the corresponding unit e g TeV for Tera electron volt This feature of the IDL language makes the input files more readable and diminishes drastically the possibility of errors in the specifications especi
92. ard primary particles that will be the actual shower primaries Section 3 5 page 70 contains a detailed description about how to build and use such kind of modules parstring is an optional parameter string can contain embedded blanks that is portably passed to the external module ADFile Syntax ADFile On Off Default ADFile is equivalent to ADFile On ADFile Off is assumed in case of missing specification d If ADFile On is specified then an ASCII dump file will be generated upon task completion The ASCII dump file ADF is a portable version of the internal dump file IDF that can be 116 APPENDIX B IDL REFERENCE MANUAL transferred among different platforms AirAvgZ A Syntax AirAvgZ A number Default AirAvgZ A 0 5 s h Sets the value of the average ratio Z A for air This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES AirRadLength Syntax AirRadLength number Default AirRadLength 37 1 s h Sets the value of the radiation length for air expressed in g cm This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES AirZeff Syntax AirZef f number Default AirZeff 7 3 s h Sets the value of the effective atomic number Z for air This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future ve
93. are muons are represented as 2D false color plots left column and contour curves plots right column Notice that the data corresponds to a single 30 EeV inclined proton shower zenith angle 60 degrees simulated using the AIRES extended thinning algorithm with a 1078 thinning level and Wy 20 in number of processed entries this is roughly equivalent to a 6 x 107 relative level Hillas thinning algorithm The outstanding characteristic of these plots if that the isondensity curves do not posses cylindric symmetry and thus the calculation of lateral distributions must be done with special care when the showers are not vertical Inclined showers can be also significantly affected by the effect of the Earth s magnetic field In figure 2 19 the positive and negative muon distributions are displayed using 2D diagrams similar to those of figure 2 18 The artificially large field strength used for this example 70 uT helps to put into clear evidence the effect of the geomagnetic deflections The total u u distribution becomes broader in the direction of the normal to the plane determined by the magnetic field and the shower axis than its counterpart for the case of no magnetic field This effect also remains evident when projecting the distributions onto the shower front plane In the case of the lower plots of figure 2 19 the projection algorithm takes into account the shower attenuation A detailed description of that procedure is beyond the sco
94. are stored in the IDF file and can be retrieved in several ways see below The complete list of currently available output data tables more than 180 is placed in appendix C page 137 Notice however that a set of simulations created using a determined version of AIRES must be ended using the same version 77 78 CHAPTER 4 MANAGING AIRES OUTPUT DATA 4 1 1 The summary file The summary file extension sry can be divided into two parts i The general section which includes data on the evolution of the simulations as well as some basic shower observables ii Tables section containing data tables accordingly to user s specifications The summary file is generally written as a plain text file this is the default However the IDL instruction LaTeX permits generating summaries that can be processed using the I4TRX type setting system If the IEX switch is enabled then the AIRES system will generate two files namely taskname sry and taskname tex The last of these two files can be normally processed by a standard ISTRX system On the other hand it is also possible to instruct any of the AIRES programs not to write the summary file To do this just include the directive Summary Off into the input data stream General section The general section of the summary file begins with computer related information task and user identification CPU time usage etc It also includes information about the input parameters used an
95. ary Off directives disables the summary file This is of course optional but might be useful when the user is just interested in creating table files The first ExportTables directive the abbreviated name will be correctly interpreted by any of the AIRES main programs indicates that all the tables whose numbers are in the range 1205 1211 must be exported with the default options Looking at the listing in appendix C page 137 it comes out that the involved tables are tables number 1205 1207 and 1211 The second export directive instruct AIRES to export table 1211 with the option of listing the slant depths of the observing levels that is measured along the shower axis equation 2 8 By default Option r all atmospheric depths listed within exported tables are vertical depths In the second export directive the option string ds modifies the default settings d indicates that the particle numbers must be normalized to particle densities expressed in particles m and s suppresses the file header only the tables will be written This last option may be useful when the exported files are read by other applications piped Suppressing the file header however may lead to not understandable files especially if they are not processed at the moment they are produced It is therefore recommended to always keep such information and it must be also taken into account that all the header lines are commented out by means of a leading comme
96. as measured in atmospheric depth into two upper lower 20 80 zones The number of defined observing levels affects the degree of detail of the monitoring of the longitudinal shower development and some applications usually require that this number be as large as possible On the other hand such setting may lead to the generation of very big longitudinal particle files since a large number of data records are generated as long as every particle crosses the observing levels To overcome this difficulty AIRES includes a selection mechanism to avoid including in the compressed file the information related with all the defined observing levels Consider the following illustrative example ObservingLevels 100 SaveInFile lgtpcles e e RecordObsLevels None RecordObsLevels 1 RecordObsLevels 4 RecordObsLevels 10 90 10 RecordObsLevels Not 20 The first directive sets the number of observing levels to 100 and the second one enables particle saving in the longitudinal particle tracking file In this case only electrons and positrons will be recorded Notice that the longitudinal file is disabled by default and therefore it is necessary to use unless one SaveInFile instruction to enable it The default action is to record particles crossing any of the defined observing levels and the remaining instructions are placed to override this default setting The directive RecordObsLevels None eliminates all the defined observing levels from the The
97. at 1077 thinning level required some 6300 times more CPU time than the ones done with 107 thinning level Notice also that the mean positions of the points corresponding to any given depth do not present any evident dependence with the thinning energy as expected since the Hillas thinning algorithm is an unbiased statistical sampling technique This observation applies also for the plots of figures 2 8 page 32 and 2 9 page 33 The degree of reduction of the fluctuation does depend on the observable considered In figure 2 8 page 32 the lateral distribution of ground electrons and positrons is displayed again for different thinning levels It is noticeable the degree of persistence of the noisy fluctuations which are not completely eliminated even in the 107 relative thinning case The lateral distribution of muons displayed in figure 2 9 page 33 reflects another characteristic of the thinning algorithm Even if the fluctuations are very large for 10 relative thinning level they CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 31 5e 10 Fo 5e 10 F a b a 4e 10 Hi a 4e 10 J E E a E 3e 10 if 3e 10 F laz ao a a 2e 10 i 2e 10 1 3 i 1e 10 F J 1e 10 3 J 0 assessorati fi fi fi 0 fi fi fi 0 200 400 600 800 1000 0 200 400 600 800 1000 X g em2 X g em2 5e 10 r 5e 10 F c d a 4e 10 J a 4e 10 J 2 2 3e 10 r J
98. ation Stopped simulations can always be restarted using aireslaunch 5 2 2 Performing custom operations between processes Every time a process ends the ARS checks for the existence of a executable script named After Process case sensitive first in the current working directory and then if not found in the default directory of the user s account HOME directory If the file is found it is executed The complete command line used when invoking the AfterProcess macro is the following AfterProcess spool tn msg rc trial totsh lastsh prog where spool is the spool identification tn is the task name msg is a message string coming from the simulation program Normally it takes the values End OfTask or EndOfRun indicating if the current task was or not finished respectively Other values are also possible and correspond to abnormal situations re is anumeric parameter taking the value 2 if the run has been stopped using an AIRES STOP file command airesstop gt See section 3 1 page 45 104 CHAPTER 5 THE AIRES RUNNER SYSTEM trial is anumeric variable counting the number of trials for the current run Generally takes the value 1 but in certain circumstances for example when relaunching AIRES after a system crash it can take larger values totsh is the total number of showers for the current task lastsh is the last completed shower prog is the instruction used to invoke AIRES which includes the full name of
99. ations performed using the old versions of SIBYLL or QGSJET programs AiresS16 or AiresQ99 respectively where the nucleus nucleus collisions APPENDIX B IDL REFERENCE MANUAL 127 paths are always evaluated by means of the built in AIRES nuclear fragmentation model This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES MuonBremsstrahlung Syntax Muonbremsstrahlung On Off Default Muonbremsstrahlung is equivalent to Muonbremsstrahlung On Muonbremsstrahlung On is assumed in case of missing specification s h Switch to include exclude the muon bremsstrahlung 18 and muonic pair production processes from the muon propagating algorithms These interactions are enabled by default Disabling them may lead to non realistic air shower simulations This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES MuonCutEnergy Syntax MuonCutEnergy energy Default MuonCutEnergy 10 Mev s Minimum kinetic energy for muons Every muon having a kinetic energy below this thresh old is not taken into account in the simulation it is forced to a decay energy must be greater than or equal to 500 keV NuclCollisions Syntax NuclCollisions On Off Default NuclCollisions is equivalent to NuclCollisions On NuclCollisions On is assumed in case of missing specification s h Switch to inc
100. ays Electrons Positrons Muons Muons Pions Pions Kaons Kaons Neutrons Protons Antiprotons Nuclei Other charged pcles Other neutral pcles e and e mu and mu pit and pi K and K 140 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 Code 2491 2492 2493 2501 2505 2506 2507 2508 2511 2512 2513 2514 2521 2522 2523 2541 2591 2592 2705 2707 2711 2713 2791 2792 2793 2801 2805 2806 2807 2808 2811 2812 2813 2814 2821 2822 2823 2841 2891 2892 Table name APPENDIX C OUTPUT DATA TABLE INDEX Unweighted lateral distribution All charged particles Unweighted lateral distribution All neutral particles Unweighted lateral distribution All particles Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy distribution at ground Energy
101. b amp irc Positioning the file after a given record This routine used in connection with crorecnumber allows emulating direct access to compressed files Notice however that a completely random access regime with very large files may eventually imply longer processing times Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile recnumber Input integer The record number A negative value is taken as zero If recnumber lt 0 the return code is always set to zero for successful operations Notice that in this case the file will be positioned at the beginning of the data records vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code The meanings of the different values that can be returned are as explained for routine getcrorecord When the return code is a record type it corresponds to the record type of the last scanned record
102. be different as well as their meanings but in all cases such data items will be set accordingly with the corresponding record sequence tables 4 1 4 2 etc In order to make the analysis programs simpler and more robust a special routine has been in cluded in the AIRES library to automatically set the adequate field indices corresponding to a given record of a certain compressed file as illustrated in the example of figure 4 2 The outstanding characteristic of this piece of code is that the elements of arrays indata and fidata are not referenced directly using numeric indices but by means of integer variables like icode for instance see figure 4 2 Those index variables are set by means of routine crofieldindex The arguments required by this routine include i The identification of the file channel ii The record type coincident with the return codes of getcrorecord already mentioned In this example 0 for the default record and 2 for the end of shower record iii The first characters of the field name Fields are identified by their names providing therefore absolute transparency to the fact that the order and number of fields may change with the file being processed The next argument of crofieldindex is set to 4 to force the program to stop in case of ambiguous or erroneous field specification thus providing a very safe processing environment iv The output argument datype returns information about the data type correspon
103. c medium is the so called vertical atmospheric depth Xy defined as follows CO X h f pte de 2 4 The integration path is the vertical line that goes from the given altitude h up to infinity The usual unit to express X is g cm In figures 2 4 and 2 5 X h Linsley s model is plotted against h Notice that X 0 1000 g cm and X h 0 for h co as expected 16 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 100 4 10 7 S 1 J 5 eb 0 1 4 S 0 01 0 001 7 0 0001 eeej EREN Figure 2 5 Same as figure 100 2 4 but for altitudes larger h km than 10 km p h can be obtained from X h via _ _ dXy h olh 2 5 Linsley s parameterization of X h 16 is done as follows i The atmosphere is divided in L layers For l 1 L layer l starts ends at altitude hy hj 1 It is clear that hy 0 and hi 1 hmax ii Xa h is given by a bbe h t hi lt h lt hi C 1 0 1 Xy h aL br h cr hL lt h lt hL 1 2 6 0 h gt hp41 Where the coefficients a b and c L 1 L are adjusted to fit the corresponding experimental data The coefficients used in AIRES which correspond to a model with L 5 layers are listed in table 2 1 and are the ones that come out from a fit to the US standard atmosphere data The Linsley s model prediction for p h plotted in figure 2 3 was obtained using this coefficient set and equations 2 6 and 2 5 Another important propert
104. cal depth Xv0 Xv0 0 is the top of the atmosphere The integer variable zendis allows to select among fixed sine and sine cosine zenith angle distributions see section 3 3 3 Arguments nobslev Input integer The number of observing levels Wo olxv Input double precision array nobslev Vertical atmospheric depths in g cm of the corresponding observing levels Xv0 Input double precision Vertical atmospheric depth in g cm of the point marking the end of the integration path If Xv0 is zero then the end of the integration path is the top of the atmosphere zendis Input integer Zenith angle distribution switch 0 fixed zenith angle 1 sine distribution 2 sine cosine distribution zenl zen2 Input double precision Minimum and maximum zenith angles degrees If zendis is 0 then zen2 is not used and zen1 gives the corresponding fixed zenith angle groundz Input double precision Ground altitude in m olxs Output double precision array nobslev Slant atmospheric depths in g cm of the corresponding observing levels 196 APPENDIX D THE AIRES OBJECT LIBRARY opencrofile FORTRAN call opencrofile wdir filename headerl1 logbase vrb channel irc C opencrofilec amp wdir amp filename amp headerl amp logbase amp vrb amp channel amp irc Opening a CIO file for reading This routine performs both the system open operation and file header processing and checking Argume
105. cation However the IGRF database imple mented in the current AIRES version contains data for the years 1955 to 1995 For dates outside that interval it is necessary to extrapolate the corresponding data in order to evaluate the geomagnetic field This may lead to inaccurate estimations for dates very far from the validity range of the model more than ten years away Nevertheless extrapolations near the given boundaries are acceptable and are of course necessary for calculations beyond the year 1995 In case of missing date specification it is set accordingly with the system time at the moment of starting the simulations Once a site and a date are set the Earth s magnetic field will be calculated by means of the IGRF model unless it is explicitly set by means of the GeomagneticField directive Let us analyze some examples see also page 123 GeomagneticField Off With this instruction the effect of the magnetic field on the motion of the charged particles will not be taken into account However the field will still be evaluated in order to determine the declination angle which is used to transform geographical azimuths into magnetic ones see page 62 GeomagneticField 32 uT 60 deg 2 deg The preceding directive instructs AIRES to fully override the IGRF estimation with the values in dicated in the parameters which respectively correspond to F I and D see section 2 1 5 Partial overriding is also supported like in the following
106. ces r to the shower axis lie in the interval ro min are processed by a resampling algorithm which conditionally keeps the particles accordingly with the following rules i Nonnumerous particles like pions nucleons etc are always saved ii For every numerous particle i e gammas electrons positrons and muons in the mentioned region 2 pe 4 4 Tmin the acceptance probability ist iii The statistical weights of the accepted particles are increased via w 4 5 Ds in order to keep unbiased the sampling algorithm The total number and energy of particles that fall within the resampling area are recorded in the end of shower record fields 8 and 19 The SaveInFile SaveNotInFile directive permits including excluding one or more particle kinds into from the compressed file Section 3 2 5 page 50 contains several illustrative examples on how to use them Notice that by default all particle kinds are enabled to be saved into the ground particle file Longitudinal tracking particle file The structure of the longitudinal tracking particle file is very similar to the already described ground particle file Both files have virtually the same beginning of shower end of shower external primary particle and special primary trailer records and there are alternative formats for the particle records For that reason it is highly recommended to the reader be fa
107. cess Syntax RunsPerProcess number Infinite Default RunsPerProcess Infinite d Number of runs within a process see also MaxCpuTimePerRun and ShowersPerRun SavelnFile Syntax SaveInFile filext particlel particle2 Default SaveInFile grdpcles All SaveInFile lgtpcles None s This directive allows to control the particles being saved in the compressed file whose exten sion is filext see directive RLimsFile particle1 particle2 are valid particle or particle The extension of a file is what goes after the dot in the file name like in fname extension for instance APPENDIX B IDL REFERENCE MANUAL 133 group names This directive together with SaveNotInFile are useful to save output file space in certain circumstances SaveNotInFile Syntax SaveNotInFile filext particlel particle2 s The syntax of this directive is similar to SaveInFile and its meaning is opposite SaveInFile filext None is equivalent to SaveNotInFile filext All SeparateShowers Syntax SeparateShowers Off number Default SeparateShowers Off s In a task involving more than one shower the compressed output files can be split into several pieces each one storing the data corresponding to number showers In particular Sepa rateShowers 1 generates one compressed file per shower while SeparateShowers Off disables file splitting SetGlobal Syntax SetGlobal Dynamic Static varname value Default No environmenta
108. cessing special primaries has been fixed AIRES version 2 2 0 15 Nov 1999 This version of AIRES consists of about 590 routines adding up to more than 80 000 lines of source code Features 1 An improved parameterization of the ete losses in air 2 A resampling algorithm which selectively saves particles located near the shower axis capa ble of reducing substantially the sizes of the compressed particle files 3 An improvement in the algorithm to process A baryons generated by QGSJET A related bug affecting noticeably about 1 of the showers has been fixed 4 The AIRES kernel is now capable of invoking external user written programs to generate sets of particles to be injected in the stacks before starting the simulation of the corresponding shower This kind of primary particle processing called special primary particles was de veloped for several purposes for example processing the first interaction of exotic primaries like neutrinos including all the particles generated by ultra high energy gamma ray conversion in the geomagnetic field before reaching the atmosphere etc 5 Upgraded version of QGSJET 6 Important extension of the AIRES object library including a series of utilities to process special primaries APPENDIX F AIRES HISTORY 223 7 Additionally lots of minor changes improvements and of course corrections of bugs AIRES version 2 0 0 relaunched 06 May 1999 This correspon
109. chosen coordinate system The vectors uxyz 1 i uxyz 2 7 uxyz 3 i 7 1 n do not need to be normalized pwt Input double precision array n Particle weights The weights must be equal or greater than one irc Output integer Return code 0 means normal return If uxyz is defined in a C environment then its two dimensions should be swapped i e double uxyz n ldu APPENDIX D THE AIRES OBJECT LIBRARY 203 speiend FORTRAN call speiend retcode C speiend amp retcode Closing the interface for the special primary particle external process This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments retcode Input integer Return code to pass to the main simulation program retcode 0 means normal return If retcode is not zero a message will be printed and saved in the log file extension Igf 0 lt retcode lt 10 10 lt retcode lt 20 20 lt retcode lt 30 and retcode gt 30 correspond respectively to information warning error and fatal messages 204 APPENDIX D THE AIRES OBJECT LIBRARY speigetmodname FORTRAN call speigetmodname mn mnlen mnfull mnfullen C speigetmodnamec amp mn amp mnlen amp mnfull amp mnfullen Getting the name of the module invoked by the simulation program that is the one specified in the definition of the corresponding special particle This routi
110. ckages are implemented in AIRES For technical reasons they are compile time implemented and are available by means of two different executable programs Aires and AiresQ containing links to SIBYLL and QGSJET respectively The current version of AIRES 2 6 0 includes links to SIBYLL 2 1 and QGSJETO1 The old versions SIBYLL 1 6 and QGSJET99 are also distributed and can be used invoking the executable programs AiresS16 and AiresQ99 respectively All the particle nucleus and nucleus nucleus interactions with projectile kinetic energy above a certain threshold are processed using the external package while the low energy ones are calculated by means of the extended Hillas splitting algorithm 4 22 or a built in nuclear fragmentation model in the cases of hadron nucleus or nucleus nucleus collisions The IDL directive ExtCollModel is an On Off switch that allows controlling the use of the exter nal package SIBYLL or QGSJET depending on the executable program being used The minimum energy required for the external package to be invoked can be altered using directives MinExtCol lEnergy and or MinExtNucCollEnergy as in the following example MinExtCollEnergy 300 GeV MinExtNucCollEnergy 500 GeV CHAPTER 3 STEERING THE SIMULATIONS 69 AIRES supports also the directive ForceModelName that is useful to ensure that a given input data set will be processed only with a determined simulation program For instance if an input data set containing t
111. code that identifies the particle The library routine crospcode is the adequate one to manage such special particle codes CHAPTER 4 MANAGING AIRES OUTPUT DATA 85 Field Name Description Integer 1 Primary particle code Stores the code of the primary particle 2 Shower number Shower number By default the first shower is labeled with the number 1 but the user can manually set the first shower number by means of the IDL directive FirstShowerNumber see page 121 3 8 Starting date and time Six fields containing respectively the year month day hours minutes and seconds corresponding to the beginning of the simulation of the corresponding shower Real 1 Primary energy GeV log The logarithm of the primary particle s energy 2 Primary zenith angle deg The zenith angle of the primary particle 3 Primary azimuth angle deg The azimuth angle of the primary parti cle 4 Thinning energy GeV The absolute thinning energy used for the respective shower 5 First interaction depth g cm2 The vertical depth of the point where the first interaction took place Xj 6 Central injection altitude m The z coordinate of the primary s injec tion point see figure 2 1 7 Global time shift sec The time to required for a particle mov ing along the shower axis at the speed of light to go from the injection point to the ground level Table 4 1 Fields contained in the beginning of shower record of compressed particle fi
112. complete list of fields is placed in table 4 5 page 89 As mentioned previously there are several record formats each one including a different subset of all the available fields In contrast with the beginning of shower and end of shower records a given field of the particle record can be assigned different field numbers As it will be seen below in this chapter this does not affect the user s processing of compressed files which can be done independently of the field number assignments There are specific IDL directives that can control the particles that are actually saved in the ground particle file To start with let us consider the directives RLimsFile and ResamplingRatio whose syntax is RLimsFile grdpcles fmin Tmax ResamplingRatio s 90 CHAPTER 4 MANAGING AIRES OUTPUT DATA grdpcles identifies the file the directive refers to and rmin and rmax represent length specifications 0 lt Tmin lt Tmax Sr is a real number sy gt 1 Such directives instruct AIRES to save unconditionally those particles whose distances to the shower axis lie within the interval rmin Tmax On the other hand all the particles whose distances to the shower axis are smaller than ro a 4 3 Sr ro is by definition not larger than fmin are not included in the ground file but their number and energy are recorded and the totals are included in the end of shower record fields 7 9 18 and 20 Finally all the particles whose distan
113. crofile vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means successful return Returned value Integer The record number If the file is not ready closed or end of file then 1 is returned APPENDIX D THE AIRES OBJECT LIBRARY 161 crorecstrut FORTRAN call crorecstruct channel nrtype nintf nrealf irc C crorecstruct amp channel amp nrtype amp nintf amp nrealf amp irc Getting information about the records of an already opened compressed file Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile nrtype Output integer The highest record type defined for the file record types range from zero to nrtype nintf Output integer array 0 nrtype Number of integer fields contained at each record type for record types from zero to nrtype No check is made to ensure that the length of the array
114. cter codes as returned by recent implementations of g77 compiler libraries e The shower CPU time is now correctly stored in the end of shower records of multi shower files Algorithm modifications Muon propagation The processes of muon bremsstrahlung and muonic pair production are now taken into account by AIRES propagating engine IGRF model The IGRF 2000 data set is the one currently used to evaluate the geomagnetic field Hadronic collisions Completely new version of the Hillas splitting algorithm tuned to produce effective approximations of more involved models Low energy cross sections are calculated from fits to experimental data Particle propagation Code has been added to fully propagate A baryons Improved meson decay procedures Electromagnetic procedures Exhaustive check of the algorithms for electromagnetic processes Low energy particles Introduced new IDL instructions ForceLowEDecays 122 and ForceLowEAnnihilation 121 to allow controlling whether or not low energy particles must be forced to decays or annihilation Thinning Separated weight factors for electromagnetic and heavy particles Other A lot of minor improvements in algorithms though the entire code and library Too many and too much technical for a detailed list 218 APPENDIX E RELEASE NOTES Installation procedure The installation scripts were substantially improved Reported problems related with the installation of AIRES 2 2 1 have
115. ctions IMPORTANT The statistical weight factor of the AIRES extended thinning algorithm is not equivalent to the param eter with the same name defined for AIRES 1 4 2 or earlier Therefore the recommended values placed in the AIRES 1 4 2 manual 12 do not apply for the current version CHAPTER 3 STEERING THE SIMULATIONS 67 The number of observing levels defined for the longitudinal tables table numbers 1000 to 1999 can be controlled using the IDL directive ObservingLevels as already explained in section 3 2 5 page 50 The lateral distribution tables table numbers 2000 to 2499 the energy distribution tables table numbers 2500 to 2999 and the mean arrival time distribution tables table numbers 3000 to 3499 are defined by default as histograms with 40 logarithmic bins either radial or energy bins depending on the distribution type plus two additional underflow and overflow bins The IDL directives RLimsTables and ELimsTables allow to control the radial and energy bins respectively as illustrated in the following examples RLimsTables 20 m 2 km ELimsTables 2 MeV 1 TeV The first directive sets the range for the standard lateral distributions The lowest end of bin 1 highest end of bin 40 is set to 20 m 2 km The underflow bin will thus correspond to all entries with distances less than 20 m while the overflow one to all entries beyond 2 km In a completely similar way the second directive sets
116. d K versus shower number Number and energy of ground neutrons versus shower number Number and energy of ground protons versus shower number Number and energy of ground pbar versus shower number Number and energy of ground nuclei versus shower number Number and energy of other grd ch pcles versus shower number Number and energy of other grd nt pcles versus shower number Number and energy of ground e and e versus shower number Number and energy of ground mu and mu versus shower number Number and energy of ground pi and pi versus shower number Number and energy of ground K and K versus shower number Number and energy of ground ch pcles versus shower number Number and energy of ground nt pcles versus shower number Number and energy of all ground particles versus shower number Xmax and Nmax charged particles versus shower number First interact depth and primary energy versus shower number Zenith and azimuth angles versus shower number 142 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 224 Code 7001 7005 7006 7007 7008 7091 7092 7205 7207 7291 7292 7293 7301 7305 7306 7307 7308 7391 7392 7405 7407 7491 7492 7493 7501 7505 7506 7507 7508 7591 7592 7705 7707 7791 7792 7793 7801 7805 7806 7807 Table name
117. d probabilities are used to select one of the possible interactions This selection defines what is going to happen with the corresponding particle at that moment 6 The interaction is processed First the particle is moved a certain distance which comes out from the mentioned stochastic method then the products of the interaction are generated New stack entries are appended to the existing lists for every one of the secondary particles that are created Depending on the particular interaction that is being processed the original particle may survive the corresponding entry remains in the stack for further processing or not the entry is deleted 7 When a charged particle is moved its energy is modified to take into account the energy losses in the medium ionization 8 Particle entries can also be removed when one of the following events happens a The energy of the particle is lower than a certain threshold energy called cut energy The cut energies may be different for different particle kinds b The particle reaches ground level c A particle going upwards reaches the injection surface d A particle with quasi horizontal motion exits the region of interest 9 After having scanned all the stacks it is checked whether or not there are remaining particle entries pending further processing If the answer is positive then all the stacks are re scanned once more otherwise the simulation of the shower is complete The group o
118. d reports on the number of particle entries processed at each stack A complete report on stack usage can be obtained using the IDL directive StackInformation On Then general information about the number and energy of particles reaching ground is displayed For all the output observables its mean standard deviation root mean square error of the mean minimum and maximum are reported The IDL directive OutputListing Full will generate an additional section containing information generally of computational nature on several output quantities defined for different algorithms The general section concludes with reports on the vertical depth of the first interaction and on the location of the shower maximum The data collected for the longitudinal development of all charged particles that is the number of charged particles N 7 that crossed the observing level 7 for alli 1 No is used to estimate the shower maximum Xmax here defined as the vertical depth of the point where the number of charged particles reaches its maximum The number of charged particles at the maximum Nmax is also evaluated The estimation of the shower maximum is done by means of a 4 parameter fit to the Gaisser 2 AE The statistical analysis is made in a shower per shower basis CHAPTER 4 MANAGING AIRES OUTPUT DATA 79 Hillas function 29 X Xp max Xo A Kar max Na X Ninax Xmax Nmax Xo and are the free paramete
119. dded to the unphysical particle counter included in the shower energy balance This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments pener Input double precision Energy GeV pwt Input double precision Null particle weight Must be equal or greater than one irc Output integer Return code 0 means normal return APPENDIX D THE AIRES OBJECT LIBRARY 201 spaddp0 FORTRAN call spaddp0O pcode pener csys ux uy uz pwt irc C spaddp0 amp pcode amp pener amp csys amp ux amp uy amp uz amp pwt amp irc Adding a primary particle to the list of primaries to be passed from the external module to the main simulation program This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments pcode Input integer Particle code accordingly with the AIRES coding system described in section 2 2 1 page 20 pener Input double precision Kinetic energy GeV csys Input integer Parameter labeling the coordinate system used csys 0 selects the AIRES coordinate system csys 1 selects the shower axis injection point system de fined in section 3 5 ux uy uz Input double precision Direction of motion with respect to the chosen coordinate system The vector ux uy uz does not need to be normalized pwt Input double
120. ding to the specified field as explained in page 149 In the particular case of longitudinal particle tracking files it is generally convenient to use the routine getlgtrecord in place of getcrorecord A complete description of getlgtrecord can be found in page 181 this routine must be used jointly with getlgtinit Closing files and ending a processing session The AIRES library routines support simultaneous processing of more than one compressed file Sev eral compressed files can be opened at the same time each one identified by the corresponding chan nel integer variable The opened files can be closed using two alternative procedures see page 145 i Routine cioclosel closes individual files cioclose closes all the currently opened files Routine cioclose should be used only if the processing session will continue after closing all files To finish an analysis program in an ordered fashion use the routine ciorshutdown This procedure performs all the required tasks to properly set down the processing system including a call to cioclose Other operations There are many other routines included in the AIRES library that provide useful tools for special analysis tasks Such routines are explained in detail in appendix D page 144 we shall limit here to a brief presentation of the most relevant ones Counting records Routines crorecinfo and croreccount count the data records contained within a compressed file CHAPTER 4 MANAGING A
121. ds to a patched release of version 2 0 0 including 1 Minor corrections to the user s manual 2 Modified lowest values for the cut energies controlled by directives ElectronRoughCut and GammaRoughCut that can be as low as 50 keV 3 Corrected bug in AiresIDF2ADF AIRES version 2 0 0 26 Apr 1999 This version of AIRES consists of about 530 routines adding up to more than 75 000 lines of source code Features 1 A complete set of options for the hadronic mean free paths or cross sections The user can select among Standard or MOCCA Bartol QGSJET and SIBYLL hadronic mean free paths independently of the external collision algorithm QGSJET or SIBYLL being used 2 A more recent version of the SIBYLL package 1 6 replaces the old 1 5 version used in previ ous releases of AIRES 3 The propagating procedures were expanded to include full kaon and 7 meson propagation 4 The algorithms for calculation of energy losses during the longitudinal and ground particle recording have been noticeably improved 5 The statistical thinning algorithm has been modified The new procedures identified as AIRES extended thinning algorithm allows to put a strict upper bound to the maximum statistical weight that a particle entry can have 6 The stack management procedures have been improved to make a more efficient use of scratch space This produces a noticeable increase in the performance of the AIRES system when processin
122. duction 18 Emission of knock on electrons 6 rays Compton and photoelectric effects 6 gt The set of considered processes is similar to the corresponding one from the MOCCA simulation program 1 but in most cases the algorithms have been improved and debugged The algorithms corresponding to the LPM effect and dielectric suppression were completely rewritten for AIRES ver sion 1 4 2 and emulate Migdal s theory 19 The procedures included in previous versions of AIRES namely 1 2 0 and 1 4 0 are numerically incorrect leading to an excessive suppression effect which affects the results of the simulations in certain circumstances 20 This bug is present also in MOCCA s LPM procedures as reported by D Heck 21 Addition ally the previous algorithms do not take into account the effect of the dielectric suppression CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 23 e Hadronic processes Inelastic collisions hadron nucleus Photonuclear reactions Nuclear fragmentation elastic and inelastic e Unstable particle decays e Particle propagation Medium energy losses ionization Coulomb and multiple scattering The hadronic inelastic collisions and photonuclear reactions are processed by means of exter nal hadronic interaction models when their energy is above a certain threshold otherwise they are calculated using an extension of Hillas splitting algorithm 4 22 AIRES includes
123. e IDF all rele vant simulation data In case of a system failure for example the simulation process can be restarted at the point of the last auto saving operation thus avoiding loosing all the previous simulation effort The processing block that goes between two consecutive auto save operations is called a run With task we mean a specific simulation job as defined by the input directives for example a task can be simulate ten proton showers and with process we identify a system process which starts when AIRES is invoked and ends when control is returned to the operating system A task can be completed after one or more processes and there can be one or more runs within a process The limit case consists in having a task finished in a single run no auto save completed in a single process the program invoked just once 3 2 The Input Directive Language IDL Both the main simulation programs Aires and AiresQ and the summary program AiresSry read their input directives from the standard input channel and use a common language to receive the user s instructions This language is called Input Directive Language IDL 45 46 CHAPTER 3 STEERING THE SIMULATIONS The IDL directives are written using free format with one directive per line there are no contin uation lines but each line can contain up to 176 characters Special characters like tab characters for example are treated as blank characters All direc
124. e included in the longitudinal tracking particle file can be now controlled by means of IDL directives 4 There are a few new routines in the AIRES library 5 Added support for unweighted tables 6 Fixed bug affecting the arrival time distribution under certain circumstances Many thanks to Pierre Billoir and Xavier Bertou LPNHE Paris France 7 Lots of minor technical improvements in the simulation programs AIRES Runner System etc AIRES version 1 4 0 29 Jan 1998 This version of AIRES consists of about 400 routines adding up to more than 63 000 lines of source code Features 1 The curvature of the earth is taken into account to evaluate particle paths and altitude gt atmospheric depth conversions 2 Improved lost particle algorithms This together with 1 allow for reliable processing of non vertical showers at all zenith angles even the quasi horizontal ones 3 New compressed output files and compressed files options Full longitudinal file and large record files that allow for more complete particle properties 4 New options for printing and exporting tables IL allowing to get normalized dN dln or dN dlog listings 5 Special non printable characters tabs for example can now be included within IDL direc tives 226 10 11 12 13 14 15 16 17 18 APPENDIX F AIRES HISTORY More restrictive bounds for primary energy Must be in the range 1 Ge
125. e obtained by scaling properly the corresponding proton nucleus mean free path This directive has no effect on simulations performed using the old versions of SIBYLL or QGSJET programs AiresS16 or AiresQ99 respectively where the nucleus nucleus mean free paths are always evaluated by means of the built in procedure This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES APPENDIX B IDL REFERENCE MANUAL 121 FileDirectory Syntax FileDirectory dopt directory Default The output and scratch directories default to the current working directory The global and export directories default to the current value of the output directory d This directive sets the output file directories dopt is a character string that can take any one of the following values A11 Output Global Export or Scratch These alternatives permit setting all the AIRES directories defined in section 3 3 2 page 60 The option All can be used to simultaneously set the output compressed file global and export directories directory is a character string not longer than 94 characters that must be recognized by the operating system as a valid directory FirstShowerNumber Syntax FirstShowerNumber fshowerno Default FirstShowerNumber 1 s A positive integer in the range 1 759375 indicating the number to be assigned to the first simulated shower The shower number
126. ean that only electrons and positrons are going to be saved in the longitudinal file and that all particles but gamma rays are going to be recorded in the ground particle file The particle kind specifications may include one or more particle or particle group names see section 2 2 1 There may be more than one of these statements for each file and their meaning depends on the order they are placed within the input data stream As an example let us consider the following statements SaveInFile somefile None SaveInFile somefile Muons 54 CHAPTER 3 STEERING THE SIMULATIONS They ensure that only muon records will be saved in file somefile The first statement clears and the second enables muons If the order is changed SaveInFile somefile Muons SaveInFile somefile None then the result is that somefile will be considered disabled because the last None specification prevents any particle kind from being saved in the corresponding file The logical switch controlled by the instruction ADF On enables the portable dump file the portable version of the IDF file The summary unit manages more than 180 output data tables that can be selectively included within the output data Each table is identified by a numerical code and the directives PrintTables and ExportTables permit including a table listing within one of the output files or generating a separate plain text file with the corresponding table respectively
127. eans that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place nrtype Output integer The highest record type defined for the file record types range from zero to nrtype nrec Output integer array 0 nrtype For each record type the number of records found No check is made to ensure that the length of the array is enough to store all the data items irc Output integer Return code 0 means successful return 158 APPENDIX D THE AIRES OBJECT LIBRARY crorecfind FORTRAN okflag crorecfind channel intype vrb infieldl rectype C okflag crorecfind amp channel amp intype amp vrb amp infield1 amp rectype Reading records until getting a specified record type The compressed file associated with channel is scanned until a record of type intype is found Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile intype Input integer Record type to find vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1
128. ection 3 2 1 The directives that follow set some characteristics of the showers that are going to be simulated The PrimaryZenAngle directive gives the shower zenith angle measured as indicated in figure 2 1 page 12 This directive and the directive PrimaryAzimAngle permit the user to completely control the inclination of the shower axis They can be used to set this inclination to a fixed value or to select variable settings selected at random with adequate probability distributions In this case the alternative syntax of the directives should be used For a more detailed description see section 3 3 3 page 61 and or appendix B page 114 The GroundAltitude specification indicates the height above sea level of the ground surface measured vertically The specification can be a length or a vertical atmospheric depth expressed in CHAPTER 3 STEERING THE SIMULATIONS 51 An example of an AIRES IDL input data set Skip amp next The directive Skip skips all text until the label amp label is found Notice that it is not equivalent to a go to statement since it is not possible to skip backwards As it can easily be seen most directive names are self explaining amp next Remark JUST AN EXAMPLE It is possible to define variables that can be used later within the input file and or be passed to output files or special primary modules SetGlobal MyVariable This string is associated with the variable SetGlobal VRem Anoth
129. ectory when not specified On the other hand the global and export directory default to the current setting of the output directory The IDL directive FileDirectory permits complete control on the listed directories For example the sequence of instructions FileDirectory Scratch mytmpdir FileDirectory Export myexportdir sets the scratch export to the strings must be meaningful to the operating system mytmpdir myexportdir The directory specifications may be either absolute or relative Relative speci fications are always with respect to the working directory In the preceding example the remaining directories are not specified and will therefore take their respective default settings The directive FileDirectory All mydir simultaneously sets the global output and export directories There is an additional set of directories that can be specified while scanning the input data The following instructions for instance InputPath dirl dir2 InputPath Append dir3 Input myinputfile inp will cause AIRES to search for file myinputfile inp in all the three directories specified by means of the InputPath directives notice the two alternative syntaxes and if not found there in the current working directory CHAPTER 3 STEERING THE SIMULATIONS 61 3 3 3 Defining the initial conditions There are two mandatory specifications related to shower parameters that must always appear within the input data namely primary partic
130. ed The primary particle can be any one of the already mentioned particles with energy ranging from less than 1 GeV up to more than 1 ZeV 107 eV It is also possible to simulate showers initiated by special primary particles via a call to a user written module capable of processing the first interaction of the primary and returning a list of standard particles suitable for being processed by AIRES Among all the physical processes that may undergo the shower particles the most important from the probabilistic point of view are taken into account in the simulations Such processes are i Electrodynamical processes Pair production and electron positron annihilation bremsstrahlung electrons positrons and muons muonic pair production knock on electrons rays Compton and photoelectric effects Landau Pomeranchuk Migdal LPM effect and dielectric suppression ii Unstable particle decays pions and muons for instance iii Hadronic processes Inelastic col lisions hadron nucleus and photon nucleus sometimes simulated using an external package which implements a given hadronic interaction model like the well known SIBYLL or QGSJET models Photonuclear reactions Nuclear fragmentation elastic and inelastic iv Propagation of charged par ticles Losses of energy in the medium ionization multiple Coulomb scattering and geomagnetic deflections The AIRES simulation system provides a comfortable environment where to perform r
131. ed in terms of IDL directives as follows Task a_first_example Primary proton PrimaryEnergy 150 TeV TotalShowers 3 End These directives like most IDL directives are self explaining and posses a simple syntax They can be placed in any order Notice that the particles are specified by their names and physical quanti ties like the energy for example are entered by means of a number plus a unit 3 2 2 Errors and input checking Every IDL directive is checked for correct syntax when it is read in Additionally some elemental tests of the values given to the directive s parameters are also made When an error is detected Special characters were not supported in AIRES 1 2 0 Actually the TaskName directive is not mandatory for a task to start but its default value GIVE_ME_A_NAME_PLEASE produces file names which are rather inconvenient to manage and so it is strongly recommended to always set the name of a task before proceeding with the simulations CHAPTER 3 STEERING THE SIMULATIONS 47 a message is written to the standard output channel Directives with errors are generally ignored Consider the following directive PrimaryEnergy 100 Mev If processed by AIRES it will give the following error message EEEE EEEE dd Mmm yyyy hh mm ss Error message from commandparse EEEE Numeric parameter s invalid or out of range EEEE gt PrimaryEnergy 100 Mev lt EEEE which indicates that the energy specification is out of ra
132. een The origin of the AIRES coordinate system O is located at sea level while O is located at the original shower injection point g is the ground altitude The z axis is parallel to the shower axis the x axis is always horizontal and the y z plane contains the z axis 1 To select the shower axis injection point system This is a special coordinate system whose z axis is parallel to the shower axis and its origin is placed at the original injection point which remains uniquely determined by the shower zenith and azimuth angles and by the injection and ground altitudes In this coordinate system illustrated in figure 3 4 the coordinates 0 0 z and the vector 0 0 1 indicate respectively the position and direction of motion of a particle that moves along the shower axis and towards the ground The process is completed with the call to speiend This ensures that all the relevant variables are transmitted back to the main simulation program which will recover the control after the external module ends Both speistart and speiend must be called only once within the entire external module Notice also that one of the AIRES random number routines namely urandomt see page 213 is used to evaluate the energy if the 7 mesons being included in the list of primary particles The random number generator is not initialized Instead its current status is passed by the main simula tion program to the external module and read in within sp
133. efile actually indicates the extension of the corresponding file like grdpcles or lgtpcles for example The program AiresQ uses the QGSJET hadronic model The QGSJET initialization routines do employ a certain time to complete up to half an hour in some systems and therefore the execution time of the QGSJET simulations may be longer than the SIBYLL ones Notice however that once the initializations are finished all the relevant data is written into a special file In the following invocations of the program such data will be read in from the file thus reducing the initialization time CHAPTER 3 STEERING THE SIMULATIONS gt gt gt gt gt gt gt gt This is AIRES version V V V dd Mmm yyyy gt gt gt gt Compiled by gt gt gt gt USER xxxxx HOST xxxxx DATE gt gt gt gt gt dd Mmm yyyy hh mm ss Reading data gt dd Mmm yyyy hh mm ss Displaying a gt gt gt gt gt gt gt gt REMARKS gt gt gt gt JUST AN EXAMPLE gt gt gt gt gt gt gt gt PARAMETERS AND OPTIONS gt gt gt gt gt gt gt gt D indicates that the corresponding default value is being used gt gt gt gt Task Name RUN CONTROL Total number of showers Showers per run Runs per process CPU time per run FILE NAMES Log file Binary dump file ASCII dump file Compressed data files Table export file s Output summary file BASIC PARAMETERS Site Date Primary particle
134. efined for the simulations while olcoord returns the coordinates of the intersections between the observing levels and the shower axis and olv2slant evaluates the slant depths corresponding to each observing level Routines olcrossed and olcrossedu decode the crossed observing levels key defined in equation 4 6 returning the variables if i and Suq see section 4 2 1 The logical function olsavemarked permits determining whether or not a given observing level is recorded into a compressed file Special primary utilities Besides the specific routines designed to process special primary particles described in detail in section 3 5 the AIRES library includes also some auxiliary routines that are useful to obtain data about the special primaries that were defined at the moment of creating the compressed file that is being analyzed crospcode and crospmodinfo are examples of such procedures Miscellaneous routines The library contains some other routines than may be useful in certain ap plications for example the pseudo random number utilities raninit urandom urandomt and grandom Gaisser Hillas function related routines fitghf ghfpars ghfx ghfin atmospheric depth utility routines line xslant etc The AIRES object library is continously evolving so additional procedures will be surely in cluded in future AIRES versions Chapter 5 The AIRES Runner System Production simulation tasks usually require large amounts of computer time
135. eistart As a consequence the generated random numbers will be different in different invocations of the external module Routine speiend writes back the final status of the random number generator and it is recovered by the main simula tion program so the numbers used in one and other program are always independent If the AIRES CHAPTER 3 STEERING THE SIMULATIONS 75 random number generator is not used within the external module then there are no alteration in the series of random numbers used by the main simulation program An actual external module to process special primaries will surely be much more complex than the one of the preceding example The user can provide special routines with the procedures needed for that purpose and use routines from the AIRES object library as well Many of the modules described in appendix D page 144 can be used within special primary programs in particular the ones directly related with the special particle interface system which provide a set of tools covering the needs of the most common situations namely Retrieval of environmental information Routine speistart starts the AIRES external module in terface and retrieves some basic variables namely shower number primary energy original injection position three coordinates vertical atmospheric depth of the original injection point ground level altitude and vertical atmospheric depth distance between the original injection point and the ground
136. eliable simulations taking advantage of present day computer technology The Input Directive Language IDL is a set of simple directives which allow for an efficient control of the input parameters of the simulation The AJRES Runner System is a powerful tool to manage long simulation tasks in UNIX vi SUMMARY environments allowing the user to coordinate several tasks running concurrently controlling the evo lution of a given job while running etc The AJRES summary program processes the internal dump files generated by the main simulation program and allows to obtain data related with physical ob servables either after or during the simulations Finally the AIRES object library provides a series of auxiliary routines to process the data generated by the simulation program in particular the data contained in the compressed output files the detailed particle data files containing per particle infor mation for particles reaching the ground crossing different observing levels during their evolution etc The present version of AIRES 2 6 0 represents a new release of the Air Shower Simulation System where many new features and algorithm improvements have been added to it The most important additions for this new version are summarized in appendices E and F Many of the developments presented for the current release were performed taking into account users suggestions and remarks The author is indebted to everybody that have contacted him
137. ensity kg m3 It is worthwhile mentioning that Linsley s model is limited to altitudes A lt hmax with hmax 112 8 km The density is considered to be zero for h gt hmax This approximation helps very much to simplify different algorithms used in air shower simulations while being absolutely justified since only affects an atmospheric zone placed much above the region where the air showers take place which at most extends up to 50 vertical kilometers above sea level CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 15 1000 900 800 700 600 500 X h g em2 400 300 200 100 0 1 1 10 100 h km Figure 2 4 Vertical atmospheric depth Xy versus vertical altitude over sea level h accordingly with Linsley s model 16 For the same reason the chemical composition of the air can be assumed to be constant in the full range of non vanishing density 0 lt h lt hmax AS shown in figure 2 2 this only affect the very upper layer of the atmosphere with altitudes larger than 90 km A further approximation that will be made when necessary is to assume that the air is a pure substance made with air atoms whose nuclei possess charge Zeg and mass number Aeg To match the actual molecular weight it is necessary to set Zeg 7 3 and Zeg Aeg 0 5 1 The density of the air is not directly used by the related algorithms The quantity that naturally describes the varying density of the atmospheri
138. er T Stanev Proc 26th ICRC Utah 1 415 1999 7 N N Kalmykov and S S Ostapchenko Yad Fiz 56 105 1993 Phys At Nucl 56 3 346 1993 N N Kalmykov S S Ostapchenko and A I Pavlov Bull Russ Acad Sci Physics 58 1966 1994 8 The data software and documentation related with the International Geomagnetic Reference Field are distributed by the National Geophysical Data Center Boulder CO USA and can be obtained electronically at the following Web address www ngdc noaa gov 9 R T Fletcher T K Gaisser P Lipari and T Stanev Phys Rev D 50 5710 1994 J Engel T K Gaisser P Lipari and T Stanev Phys Rev D 46 5013 1992 10 NETLIB is a public collection of mathematical software papers and databases that can be accessed through Internet at the World Wide Web address www netlib org 11 CERN Program library Long Writeup Q121 1995 12 S J Sciutto AIRES users guide and reference manual version 1 4 2 Auger technical note GAP 98 032 1998 228 REFERENCES 229 13 National Aerospace Administration NASA National Oceanic and Atmospheric Administra tion NOAA and US Air Force US standard atmosphere 1976 NASA technical report NASA TM X 74335 NOAA technical report NOAA S T 76 1562 1976 14 R C Weast editor CRC Handbook of Chemistry and Physics 61st edition pp F206 F213 CRC Press Boca Raton FL USA 1981 15 B Rossi High ene
139. er axis tshift Output double precision array nobslev Observing levels time shifts toi i 1 No in ns that is the amount of time a particle moving at the speed of light needs to go from the shower injection point to corresponding intersection point oi Yoi Zoi mx my Output double precision array nobslev Coefficients of the planes which are tangent to the observing levels and pass by the corresponding intersection points irc Output integer Return code Zero means successful return 192 APPENDIX D THE AIRES OBJECT LIBRARY olcrossed FORTRAN call olcrossed olkey updown firstol lastol C olcrossed amp olkey amp updown amp firstol amp lastol This routine reconstructs the information contained in the crossed observing levels key one of the data items saved at each particle record in any longitudinal tracking compressed file This key encodes the first and last crossed observing observing levels and the direction of motion The encoding formula defined in equation 4 6 where L ip and i correspond to olkey firstol and lastol respectively The routine returns all the variables of the right hand side of equation 4 6 The variable associated to Suq Updown is set in a slightly different way It is be set to 1 when the particle goes upwards and to 1 otherwise Arguments olkey Input integer Key with information about the crossed observing levels updown Output integer Up down i
140. er axis with the plane orthogonal to that axis and containing the point x0 yO z0 t0beta Input double precision The meaning of this argument depends on the current value of tsw It can be the absolute injection time ns time at original injection is taken as zero or the speed of a particle divided by c irc Output integer Return code 0 means normal return 208 APPENDIX D THE AIRES OBJECT LIBRARY speistart FORTRAN call speistart showerno primener injpos xvinj zground xvground dgroundinj uprim C speistart amp showerno amp primener amp injpos 1 amp xvinj amp zground amp xvground amp dgroundinj amp uprim 1 Starting the interface for the special primary particle external process This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments showerno Output integer Current shower number primener Output double precision Primary energy GeV injpos Output double precision array 3 Position of the initial injection point with respect to the AIRES coordinate system in meters xvinj Output double precision Vertical atmospheric depth of the injection point in g cm zground Output double precision Altitude og ground level in m a s 1 xvground Output double precision Vertical atmospheric depth of the ground surface in g cm dgroundinj Output double precision Distance fro
141. er data items corresponding to the most recently opened com pressed file Notice that some additional input parameters must be retrieved using routines getinpreal getinpint or getinpswitch see pages 176 179 Arguments intdata Output integer array Integer data array The calling program must provide enough space for it The following list describes the different data items 1 2 4 5 6 8 9 10 14 15 Number of different primary particles Reserved for future use Primary energy distribution 0 fixed energy 1 varying energy Zenith angle distribution 0 fixed angle 1 sine distribution equation 3 4 2 sine cosine distribution equation 3 6 Azimuth angle distribution O 10 fixed angle geographic azimuth 1 11 varying angle geographic azimuths Number of observing levels Atmospheric model label See page 116 Reserved for future use First shower number realdata Output double precision array Real data array The calling program must provide enough space for it The following list describes the different data items 1 2 3 4 5 6 7 8 Minimum primary energy GeV Maximum primary energy GeV Exponent y of energy distribution equation 3 2 Minimum zenith angle deg Maximum zenith angle deg Minimum azimuth angle deg Maximum azimuth angle deg Thinning energy parameter gt The thinning energy parameter t p Must be interpreted as follows When p
142. er variable Remark VRem This expands to Remark Another variable Import HOME Importing OS environmental variables The input directives define a task Tasks are identified by their task name and eventually version If not defined the version is zero Task mytask Use Task mytask 5 to explicitly set task version to 5 The following three directives are mandatory have no default values TotalShowers 2 PrimaryParticle Proton PrimaryEnergy 1 5 PeV The remaining directives allow controlling many parameters of the Simulations The respective parameters will take a default value whenever the controlling directive is not present PrimaryZenAngle 15 deg Thinning l e 4 Relative Relative or absolute specifications allowed Ground 1000 g cm2 You can freely set the number of observing levels to record the shower longitudinal development You can define up to 510 observing levels and optionally altitude of the highest and lowest levels ObservingLevels 41 100 g cm2 900 g cm2 Figure 3 1 Sample AIRES input CHAPTER 3 STEERING THE SIMULATIONS Threshold energies Particles are not followed below these energies GammaCutEnergy ElectronCutEnergy MuonCutEnergy MesonCutEnergy Pions Kaons NuclCutEnergy Nucleons and nuclei Some output control statements Compressed particle data files related directives SavelInFile lgtpcles e e SaveNotInFile
143. erRun 58 133 Site 64 115 123 134 Skip 50 51 134 SpecialParticLog 76 134 StackInformation 78 134 Summary 78 80 107 134 TableIndex 79 130 135 TaskName 46 51 80 107 135 ThinningEnergy 51 66 135 ThinningWFactor 66 135 216 TotalShowers 46 51 59 75 135 Trace 47 48 101 136 TSSFile 83 136 216 x 48 119 dynamic static directives 46 57 59 114 format 46 114 hidden directives 48 58 70 114 physical units 48 49 222 reference manual 114 input file checking 46 101 installing AIRES 9 109 218 INDEX internal dump file vi 8 45 57 59 60 67 68 77 103 106 131 188 221 224 accessing 96 portable format 54 57 60 77 107 115 224 processing with AIRES summary program 77 International Geomagnetic Reference Field 4 20 64 117 123 217 221 226 knock on electrons v 3 4 22 23 218 221 lateral distributions 2 4 27 28 30 38 67 132 139 BIEX format for summary files 78 125 loadumpfile see AIRES object library log file 57 60 76 134 longitudinal development 2 4 27 28 30 36 63 67 77 78 128 137 deposited energy 142 in energy 36 52 138 low energy particles 142 low energy particles 70 annihilation 121 decay 122 LPM effect v 3 4 22 26 70 118 125 225 226 magnetic azimuth 62 129 mean free path 24 hadronic 25 69 126 nucleus nucleus collisions 25 120 126 mixed composition 61 72 MOCCA 1 2 6 16 22 23
144. eristic of the atmospheric medium is that of being inhomogeneous Its density for instance diminishes six orders of magnitude when the altitude above sea level passes from zero to 100 km and another additional six orders for the range 100 km to 300 km 14 This fact is taken into account in the model we have selected where most of the relevant observables are regarded as functions of the altitude above sea level or vertical altitude h The atmosphere is thus a spherically symmetric layer a few hundreds kilometers thick whose internal radius is the Earth s radius 6370 km For a variety of processes that the particles can undergo during the development of the shower it is essential to know the chemical composition as well as the density of the medium they are passing through 15 For this reason we have studied the behavior of these two quantities especially their dependence with the vertical altitude The chemical composition of the air as given by the mean molecular weight remains virtually unchanged in all the region 0 lt h lt 90 km and diminishes progressively for larger values of A This clearly shows up in figure 2 2 where the US standard atmosphere mean molecular weight 14 has been plotted versus the vertical altitude The constant value M 28 966 is the mean molecular weight corresponding to an atomic mixture of 78 47 N 21 05 O 0 47 Ar and 0 03 other elements The corresponding mean atomic weight atomic number i
145. es see special primary particles arrival time distributions 67 ARS 0 ars see AIRES Runner System ASCII dump file see internal dump file portable format atmospheric depth 15 116 slant 17 17 18 100 195 214 224 vertical 15 27 87 89 backwards compatibility 77 84 bremsstrahlung v 3 4 22 23 118 cioclose see AIRES object library cioclosel1 see AIRES object library ciorinit see AIRES object library ciorshutdown see AIRES object library clockrandom see AIRES object library comment characters in output files changing 80 81 117 INDEX compressed output files vi 2 5 8 9 53 57 60 76 83 112 132 133 144 225 Compton effect v 3 4 22 computer requirements 9 33 35 converting IDF files to ADF portable format 107 CORSIKA 94 particle codes 94 146 cosmic neutrinos 70 crofieldindex see AIRES object library crofileinfo see AIRES object library crofileversion see AIRES object library crogotorec see AIRES object library croheaderinfo see AIRES object library croinputdata0 see AIRES object library crooldata see AIRES object library croreccount see AIRES object library crorecfind see AIRES object library crorecinfo see AIRES object library crorecnumber see AIRES object library crorecstrut see AIRES object library crorewind see AIRES object library crospcode see AIRES object library crospmodinfo see AIRES object library crospnames see AIRES object library
146. es use of several external parameters that can be set by means of IDL directives The thinning energy Ern is the most important param eter of the thinning algorithm As illustrated in figure 3 1 page 51 the directive ThinningEnergy permits setting Fn either absolutely or relative to the primary energy The directive ThinningWF actor allows controlling the maximum weight parameter wiEM de fined in section 2 3 page 27 The specification ThinningWFactor 2 5 sets the weight factor W of equation 2 23 to 2 5 to be used with electromagnetic particles Recommended values for W are in the range 0 1 to 50 the default value is 12 Setting Wy gt 100 is practically equivalent to Wy on see section 233 The weight factor that is used with non electromagnetic particles m can also be set by the user The directive EMtoHadronWFRatio permits setting the ratio Apy defined in equation 2 24 The default value Agy 88 is normally adequate but some applications may require performing simulations with a different relation between electromagnetic and non electromagnetic weight factors and in such cases the mentioned directive is useful to change the ratio as needed 3 3 6 Output table parameters The output tables listed in appendix C page 137 are automatically calculated during the simulations and the directives to retrieve these data will be explained in chapter 4 page 77 Many of these tables can be customized by means of IDL instru
147. esponding call as illustrated in the example of figure 3 3 Additionally there are two other related library routines available namely spaddpn page 202 to append with a single call a set of various primary particles and spaddnull page 200 to include null unphysical particles A null particle is not included in the simulations but its energy is added to the global null particle energy counter Nuclei can be normally appended to the particle list Nuclear codes can be conveniently evaluated using routine nuclcode page 189 76 CHAPTER 3 STEERING THE SIMULATIONS Changing the injection coordinates and time After the initial call to speistart the injection point is set to the original injection point defined by the global parameters entered within the input data zenith and azimuth angles etc The coordinates with respect to the AIRES coordinate system of the original injection point are returned by speistart this corresponds in the example of figure 3 3 to array default_injection_position The injection coordinates and time can be changed at any moment using routine spinjpoint page 207 Setting the point of first interaction When using normal primary particles AIRES evaluates au tomatically the atmospheric depth where the first major interaction takes place This is not possible in the case of a special particle when a series of primaries are injected before starting the simulations and the default action will be to set the firs
148. eter value The calling program must ensure that there is enough space to store the string slen Output integer Length of the current parameter value On error slen is negative APPENDIX D THE AIRES OBJECT LIBRARY 179 getinpswitch FORTRAN value getinpswitch dirname C value getinpswitchc amp dirname Getting the current value for an input static logical switch corresponding to the most recently opened compressed file This routine is used to get from the current file s header those logical input parameters not returned by routine croinputdata0 see page 154 Arguments dirname Input string Name of the IDL directive associated with the parameter can be abbreviated accordingly with the rules described in appendix B Returned value Logical The current setting for the corresponding parameter In case of error the returned value is undefined 180 APPENDIX D THE AIRES OBJECT LIBRARY getlgtinit FORTRAN call getlgtinit channel vrb irc C getlgtinit amp channel amp vrb amp irc Initializing internal data needed to process records from compressed longitudinal particle track ing files by means of routine getlgtrecord and related ones This routine should be called immediately after opening the corresponding compressed file Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine
149. extended thinning algorithm is unbiased while ensuring by construction that all the particle weights be smaller than the externally specified maximum value W of equation 2 23 It is worthwhile mentioning that this procedure is not equal to the thinning algorithm of Kobal Filip i and Zavrtanik 5 even if both algorithms do use the concept of keeping bounded the statis tical weights 2 3 3 How does the thinning affect the simulations The effect of the standard thinning on different observables evaluated during the simulations can be seen in figures 2 7 2 9 All these simulations were done using identical initial conditions 101 eV proton showers with vertical incidence and considering four different thinning energies namely En Eprim 1078 10 4 10 and 1077 In all cases the weight limiting mechanism was disabled Figure 2 7 page 31 corresponds to the longitudinal development of all the charged particles that is the total number of charged particles crossing the different observing levels as a function of the observing levels vertical depth The plots in this figure show clearly how the statistical fluctuations diminish systematically as long as the thinning energy is lowered Compare the plot for 107 relative thinning with the smooth plots obtained for the cases 1076 and or 1077 As mentioned the CPU time required increases each time the thinning energy is lowered It is interesting to mention that the simulations done
150. f algorithms related with interaction selection and processing as well as calculation of energy losses is the group of physical algorithms In the current version of AIRES many of such algorithms are equivalent or similar to the ones implemented in the program MOCCA 1 The most important air shower observables are those related with statistical distributions of par ticle properties To evaluate such quantities the simulation engine of AIRES also possesses internal monitoring procedures that constantly check and record particles reaching ground and or passing across predetermined observing surfaces located between the ground and injection levels From this description it shows up clearly that the air shower simulation programs consist of various interacting procedures that operate on a data set with a variable number of records modifying its contests increasing or decreasing its size accordingly with predetermined rules It is necessary to do a modular design of such a program to make it more manageable and this is particularly relevant for the case of the algorithms related with the physical laws that rule the interactions where as mentioned there are still open problems requiring continuous change and testing of procedures CHAPTER 1 INTRODUCTION 7 Log sry and tss files Input file Exported tables IDL parser Initialization Job control and input check utilities physical data routines KERNEL Log and summary units
151. f observing level 7 and let ro ri sr 3 Any particle crossing observing levels will not be saved in the longitudinal file if one of the following conditions is true a x lt ro and y lt roi b x gt Tmax OF y gt Tae Notice that the parameter controlled by directive ResamplingRatio is global that is its last setting applies to every one of the compressed files in use CHAPTER 4 MANAGING AIRES OUTPUT DATA 93 x and y are the Cartesian coordinates of the particle at observing level f measured from the intersection between the shower axis and the corresponding observing level 4 Gammas electrons positrons and muons crossing observing levels and verifying the two fol lowing conditions a z lt rig and y lt rmin b x gt ro or y gt Toi in the same notation of the previous point will be conditionally kept with probability and reweighting factor given by equations 4 4 and 4 5 respectively 5 All the particles not fulfilling the conditions of the preceding points will be unconditionally saved in the file These rules set varying limits for the zone of excluded particles In the zone near the shower axis all particles crossing observing levels placed above X will be saved then the exclusion zone enlarges proportionally to the depth of the observing level reaching the value indicated in the RLimsFile directive at the ground depth Notice that X divides the complete shower path
152. f the following e The main air shower simulation programs Aires AiresQ AiresS16 and AiresQ99 containing MOCCA SP is a newer version of the MOCCA program which incorporates some improvements with respect to the original version developed by A M Hillas 3 AIRES and MOCCA input parameter sets are different and therefore initial conditions that are equivalent for both programs can be accomplished only in selected particular cases The version of QGSJET installed in AIRES 2 6 0 is dated 12 Feb 2002 and is usually referred as QGSJETO1 An older version of QGSJET is also included with the distribution that can be used to make comparisons gt The version of SIBYLL installed in AIRES 2 6 0 is the version 2 1 dated 02 May 2002 An older version of SIBYLL 9 is also included with the distribution that can be used to make comparisons CHAPTER 1 INTRODUCTION Propagated particles Gammas Leptons e p Mesons 7 nE N K s K Baryons p p n A Nuclei up to Z 36 Neutrinos are generated in decays and accounted for their number and energy but not propagated Primary particles All propagated particles can be injected as primary particles Multiple and or exotic primaries can be injected using the special pri mary feature Primary energy range From 800 MeV to 1 ZeV 107 eV Geometry and environment Incidence angles from vertical to horizontal showers The Earth s curvature is taken int
153. f the magnetic field it is necessary to specify both a geographic place and a date The directive Site tells AIRES the name of the site selected for the simulations For example Site SouthPole indicates that the selected place is SouthPole This name is one of the predefined locations that form the AIRES site library Besides SouthPole this library initially contains several other sites related with air shower experiments All the predefined sites are listed in table 3 2 To specify a site that is not included among the predefined ones it is first necessary to append it to the site library by means of the AddSite directive Let us consider for instance the following directive AddSite cld 31 5 deg 64 2 deg 387 m A new site cld is defined The command parameters represent respectively the latitude longitude and altitude above sea level that correspond to the defined site The name string cannot contain more than 16 characters names are case sensitive and must be different to all the previously defined ones CHAPTER 3 STEERING THE SIMULATIONS 65 The Date directive defines the date of an event There are two alternative syntaxes as displayed in the following examples Date 1998 2 Date 1998 3 1 In the first statement the date is given as a floating point number taking the year as the time unit while in the second the format year month day is used There are no special restrictions on the date specifi
154. ferent formats i Absolute In this case fluc represents a positive magnetic field strength ii Relative fluc adopts the format number Relative and refers to the ratio between the actual fluctuation strength and the average value of the magnetic field iii In percent fluc adopts the format number number corresponds to a relative specification multiplied by 100 The effect of magnetic field fluctuations is explained in section 3 3 4 page 64 GroundAltitude Syntax GroundAltitude altdepth GroundDepth altdepth Default The altitude of the site currently in effect s Ground level altitude altdepth can be either a length specification ranging from 0 to 112 km or an atmospheric depth specification ranging from 0 to 1033 g cm Help Syntax Help tables sites help tables sites 2 tables sites d The action of the Help directive is to type a brief summary of IDL directives output data tables histograms or sites defined in the AIRES site library Help gives a full IDL directive list including all hidden directives The form is equivalent to the combined action of Help and Prompt On 124 APPENDIX B IDL REFERENCE MANUAL Import Syntax Import Dynamic Static varname Default No environmental variables are imported by default d Importing environment variables The operating system environment variable varname is imported and stored as an active variable that can eit
155. for dmax at different altitudes At sea level for example where the vertical depth is approximately 1030 g cm and the density of the air is 1 22 kg m we obtain dmax lt 5 5 km 2 14 The same calculation for 100 km above sea level yields dmax lt 24 km 2 15 The boundaries of used by AIRES see section 2 1 1 agree with these results 2 1 5 Geomagnetic field All charged particles that move near the Earth are deflected by the geomagnetic field Such deflections are taken into account in the internal algorithms of AIRES The Earth s magnetic field B is described by its strength F F B its inclination I defined as the angle between the local horizontal plane and the field vector and its declination D defined as the angle between the horizontal component of B H and the geographical North direction of the local meridian The angle I is positive when B points downwards and D is positive when H is inclined towards the East Let Bz By Bz be the Cartesian components of B with respect to the AIRES coordinate system section 2 1 1 They can be obtained from the field s strength and inclination via B FcosI By 0 B Fsinl 2 16 This requirement is more stringent that the one used for AIRES version 1 4 2a or earlier The original equations 12 were not adequate in certain particular conditions namely quasi horizontal showers and were thus modified 20 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES By
156. for some special applications like generating a single random seed for example Multiple calls may eventually return correlated numbers if there is no enough time between invocations Nevertheless a sequence of different numbers passes direct 1d and 2d chi square tests ensuring a minimum quality for the generated numbers Returned value Double precision The uniform pseudo random number APPENDIX D THE AIRES OBJECT LIBRARY 149 crofieldindex FORTRAN idx crofieldindex channel rectype fieldname vrb datype irc C idx crofieldindex amp channel amp rectype amp fieldname amp vrb amp datype amp irc Returning the index corresponding to a given field within a compressed file record It is conve nient to use this routine to set integer variables and use them to manage the data returned by getcrorecord as explained in section 4 2 2 page 94 Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile rectype Input integer Record type 0 for default record type fieldname Input character string First characters of field name enough characters must be provided to make an unambiguous specification vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the
157. g see AIRES object library getinpswitch see AIRES object library getlgtinit see AIRES object library getlgtrecord see AIRES object library ghfin see AIRES object library ghfpars see AIRES object library ghfx see AIRES object library global variables 50 51 96 117 133 175 222 grandon see AIRES object library hadronic cross sections 4 24 25 69 126 low energy 126 221 hadronic models 3 5 23 68 120 122 126 Hillas A M 2 3 23 28 68 217 218 IDF or idf see internal dump file IDL see Input Directive Language idlcheck see AIRES object library IGRE see International Geomagnetic Reference Field Input Directive Language v 2 8 45 216 218 225 directives 48 123 50 51 80 115 amp 50 115 AddSite 64 115 134 AddSpecialParticle 71 72 75 115 124 129 ADFile 52 54 107 115 AirAvgZ A 70 116 AirRadLength 70 116 233 AirZeff 70 116 Atmosphere 116 Brackets 116 218 CheckOn1Ly 47 48 101 117 CommentCharacter 80 81 117 Date 65 117 De1Global 50 117 218 DielectricSuppression 70 118 DumpF ile 118 ElectronCutEnergy 52 118 218 Elect ronRoughCut 70 118 218 223 ELimsTables 67 118 EMt oHadronWFRatio 66 119 218 End 46 52 107 114 119 Exit 48 119 ExportPerShower 81 119 ExportTables 52 54 80 81 107 119 137 ExtCollModel 68 120 ExtNucNucMFP 69 120 216 FileDirectory 60 121 FirstShowerNumber 75 85 121 ForceInit 59 121
158. g Full Miscellaneous parameters Other parameters not included in the preceding sections 3 3 More on IDL directives 3 3 1 Run control In the example of section 3 2 5 page 50 no specifications are made about the duration of processes and runs This fact shows up in the variables listed in the run control section of the listing of figure 3 2 page 55 when the default setting Infinite is in effect for the number of showers per run the num ber of runs per process and the CPU time per run With such settings the auto save mechanism for fault tolerant processing is disabled The IDF file will be saved only after finishing all the simulations specified with the input directives This can be acceptable for a short simulation in a reliable computer system For heavy tasks it is recommended to split the simulations into processes and runs It is worthwhile mentioning that the auto save restore operations do not alter the results of the simulations which are bitwise identical independently of the number of such operations performed The IDL directives ShowersPerRun MaxCpuTimePerRun and RunsPerProcess provide ef fective control on the computational conditions of the simulations The following examples illustrate how them can be used RunsPerProcess 1 MaxCpuTimePerRun 2 hr These two instructions indicate that a new run should begin every two CPU hours Since the number of runs per process is 1 a new run will also imply the beginning of
159. g showers in extremely hard thinning conditions 7 Longitudinal lateral energy and time distribution tables can now be saved in a per shower basis allowing the user to retrieve full information on particular showers using the standard features of the summary program This feature can be disabled when necessary 224 APPENDIX F AIRES HISTORY 8 Two new output data tables namely First interaction depth and primary energy versus shower number and Zenith and azimuth angles versus shower number 9 All the atmospheric depths appearing in the longitudinal development tables and or per shower tables can now be expressed also as slant depths 10 All the data generated during the simulations which is stored in the binary internal dump file DF can now be written in portable format into a portable ASCII dump file ADF which can be written when finishing a simulation task Additionally a converting program AiresIDF2ADF is provided to convert any existing IDF file into ADF format 11 The random number generator can now be initialized taking the seed from an already exis tent IDF file corresponding to a previous task This is most useful for reproducing bitwise simulation jobs when necessary 12 The AIRES object library was again expanded including a series of new modules to ease AIRES output management 13 The modules of the AIRES Runner system have been extensively revised and improved 14 This distribution inc
160. g unit either a CPU or a machine inside the cluster In the preceding examples the airestask command was invoked without spool specification The default spool is used in case of missing specification and that is what was actually done in those examples In the standard configuration there are 9 predefined spools named respectively 1 2 etc Spool 1 is the default spool The command airestask s 2 myfile will create a spool entry placed in spool 2 The user will be prompted to start the simulations if there is currently no activity related with that spool The command airesstatus 2 The ARS includes also the commands mkairesspool and rmairesspool which allow the user to respectively create and delete spool directories 106 CHAPTER 5 THE AIRES RUNNER SYSTEM will report on the simulations that are running at spool 2 In the following interactive session it is illustrated how to launch three simultaneous tasks it is assumed that the machine possesses various CPU s which can be automatically assigned to the launched processes cd directoryl aireslaunch s 1 taskl cd directory2 aireslaunch s 2 task2 cd directory3 aireslaunch s 3 p AiresQ task3 It is most important that the working directories of different tasks be also different Concurrent simulation programs running with the same working directory may generate conflicts when commu nicating with the ARS scripts This fact is stre
161. ginates a series of normal secondary particles that hit the atmosphere and originate the corresponding cascades In general such special interactions are not modeled adequately by AIRES propagating engine but it is possible to overcome this difficulty allowing the simulation program to start a shower with multiple primary particles which are the secondaries coming out from the special interactions The following are examples where the mentioned scheme applies e An exotic cosmic particle a cosmic neutrino for instance interacts and produces a series of particles that can be normally propagated by AIRES CHAPTER 3 STEERING THE SIMULATIONS 71 e An electromagnetic particle interacts with the Earth s magnetic field before reaching the at mosphere and producing a pre shower whose products finally reach the atmosphere and start interacting with it e Acosmic particle disintegrates before reaching the Earth in two or more fragments that arrive simultaneously in slightly distant points e Etc AIRES 2 6 0 allows the user to simulate showers initiated in such conditions An external user provided program will be responsible for generating the particles to be injected at the beginning of the shower This process is completely dynamic and the sets of generated primary particles may vary from shower to shower To implement such an interface is very simple The user needs to i Define the special particle within the IDL i
162. gy of ground particles GeV Energy of unphysical particles GeV Energy of neutrinos GeV Energy lost in the air GeV Energy of particles too near to the core Energy of resampled particles Energy of particles too far from the core CPU time sec Description Number of particles that were not saved in the compressed file because they were too far from the shower axis see text Vertical depth of the point where the number of charged particles is maxi mum Xmax obtained from a fit to the simulation data see section 4 1 Number of charged particles at Xmax Nmax calculated as explained in section 4 1 page 77 Total energy of the particles of real field number 2 Total energy of the particles of real field number 3 Total energy of the particles of real field number 4 Total energy of the particles of real field number 5 Total energy of the particles of real field number 6 Total amount of energy lost by contin uous medium losses ionization losses due to charged particles moving through the air Total energy in GeV of the particles of real field number 7 This field is not de fined for the longitudinal tracking parti cle file Total energy in GeV of the particles of real field number 8 This field is not de fined for the longitudinal tracking parti cle file Total energy in GeV of the particles of real field number 9 This field is not de fined for the longitudinal tracking parti c
163. he logical returned value here assigned to logical variable okflag permits determining whether or not the read operation was successful The characteristics of the read record are informed via the return code irc and the arrays intfields and realfields contain the corresponding data items Their contents depend on the file being processed and on the record type The auxiliary routines crofileinfo and crofieldindex are useful to process adequately the returned data at each case Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile intfields Output integer array Integer fields of the last read record This includes the non scaled integer quantities and in the last positions the date time specification s if any The calling program must provide enough space for this array The minimum di mension is the maximum number of fields that can appear in a record plus 1 Positions beyond the last integer fields are used as scratch working space The meaning of each data item within this array varies with the class of file processed and with the record type see also argument ire and routine crofileinfo realfields Output double precision array Real fields of the record The calling program must provide enough space for this array The meaning of each data item within this array varies with the class of
164. he simulation of the corresponding shower Total number of particles processed dur ing the simulation of the corresponding shower Total number particles that went outside the region of interest for the simulations Total number of particles whose kinetic energies fell below the corresponding thresholds Total number of particles that reached the ground level including also those particles not saved in the compressed file Number of particles generated by spe cial procedures like the splitting algo rithm for example which cannot be as sociated with physical particles This number is generally very small Total number of neutrinos Ve Ve Vus Du generated during the simulation of the current shower Number of particles that were not saved in the compressed file because they were too near to the shower axis see text Number of particles that were processed with the resampling algorithm see text Table 4 2 Fields contained in the end of shower record of compressed particle files The structure of this record does not depend on the compile time option selected for the particle record CHAPTER 4 MANAGING AIRES OUTPUT DATA Field Real 9 10 11 12 13 14 15 16 17 18 19 20 21 Name Particles too far from the shower core Shower maximum depth Xmax g cm2 Total charged particles at shower maximum Energy of lost particles GeV Energy of low energy particles Ener
165. he instruction ForceModelName QOGSJET is processed with other simulation program different from AiresQ the process will immediately be aborted with an error message When the directive is not used no check is performed and the simulations can be started with any program The cross sections used to determine the collision mean free paths can also be controlled In the current version there are several sets of hadronic cross sections available namely Standard Bartol 1 QGSJET and SIBYLL cross sections The options QGSJET99 and SIBYLL16 are also available The default mean free paths are the ones corresponding to the external hadronic package linked to the simulation program that is the SIBYLL QGSJET set for program Aires AiresQ The following example illustrates how to alter the default settings MFPHadronic Bartol MFPThreshold 120 GeV These instructions imply that the Bartol mean free paths will be used for collisions with energies over 120 GeV while the standard mean free paths will be used for the ones with lower energies The previous directives also indicate that the nucleus nucleus mean free paths will be evaluated using special algorithms included within the external hadronic packages if the projectile s energy per nucleon falls above the specified threshold otherwise the mean free path will be evaluated via a built in procedure that calculates it by scaling adequately the proton nucleus mean free path corresponding to
166. he sine probability distribution of equation 3 4 which is proportional to sin O default or S specification or the sine cosine probability distribution of equation 3 6 which is proportional to sin O cos O SC or CS specifications In this case the default for the azimuth angle is PrimaryAzimAngle 0 deg 360 deg Both minang and maxang must belong to the interval 0 90 PrintTables Syntax PrintTables mincode maxcode Options optstring PrintTables Clear Default No tables are printed by default d Tables whose codes range from mincode to maxcode are selected for being displayed in the summary output file If maxcode is not specified it is taken equal to mincode The table codes are integers A complete list of available tables more than 180 is placed in appendix C page 137 or can be obtained with directives Help tables and or TableIndex The Clear option per mits clearing the list of printed tables thus overriding all the previous PrintTables directives opstring is a string of characters to set available options n suppress plotting minimum lt and maximum gt characters m include minimum and maximum plots in the tables M do not in sert character plots make a completely numerical table instead S R use standard deviations RMS errors of the means to plot error bars r d normal density lateral distributions L l distributions normalized as d d log d d ln The default options are nSr Prompt Sy
167. hen the energy of the primary increases For ultra high energy primaries that number can be large enough to make it im possible to propagate all the secondaries even if the most powerful computers currently available are used The total number of particles in a shower initiated by a 107 eV proton primary is approximately 10 being almost impossible even to store the necessary data for such an amount of particles 28 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES The simulations are made possible thanks to a statistical sampling mechanism which allows to propagate only a small representative fraction of the total number of particles Statistical weights are assigned to the sampled particles in order to compensate for the rejected ones At the beginning of the simulation the shower primary is assigned a weight 1 At the moment of evaluating averages to obtain the physical observables each particle entry is weighted with the corresponding statistical weight For example the observables coming from the monitoring routines listed in section 2 2 3 are evaluated taking into account those statistical weights On the other hand unweighted distributions are simultaneously calculated in the cases of longitudinal lateral and energy distributions They are useful to monitor the behavior of the sampling algorithm The sampling algorithm used in AIRES is called thinning algorithm or simply thinning It is an extension of the thinning algorithm originally introd
168. her be used within the IDL input stream or passed to the compressed output files or special primary modules The Dynamic qualifier default indicates the dynamic character of the corresponding variable This means that the value currently passed to the external modules is modified each time AIRES is invoked for a given task On the other hand Static variables are set at the first invocation of AIRES and further settings have no effect InjectionAltitude Syntax InjectionAltitude altdepth InjectionDepth altdepth Default InjectionAltitude 100 km s Primary injection altitude altdepth can be either a length specification ranging from 0 to 112 km or an atmospheric depth specification ranging from 0 to 1033 g cm Input Syntax Input file d File file is inserted in the input data stream Input directives can be nested The search path for locating input files include the working directory see section 3 3 2 and all the directories that were specified with directive InputPath InputListing Syntax InputListing Brief Full Default InputListing is equivalent toInputListing Brief InputListing Brief is assumed incase of missing specification d Data related to hidden input directives are not printed in the output summary file unless the corresponding variables were explicitly set or InputListing Full was specified InputPath Syntax InputPath Append dirl dir2 Default No path besides the working direc
169. hower for example the identity of the primary particle and its energy the position of the ground surface the minimum energy a particle must have to be taken into account in the simulation the intensity and orientation of the geomagnetic field etc Additionally it is possible to define many observables that are useful to characterize the particle shower namely longitudinal and lateral distribution of particles energy distributions position of the shower maximum and so on A comfortable environment is provided by AIRES to manage all the input and output data The Input Directive Language IDL is a set of human readable input directives that allow the user to ef ficiently steer the simulations The AIRES summary program and the AIRES object library represent a set of tools to manage the output data after the simulations are finished and even during them allowing to control their evolution Data associated with particles reaching ground or crossing prede termined observing levels can be recorded into compressed output files A special data compression procedure is used to reduce as much as possible the size of the files which tends to be very large in certain circumstances The compressed files can be processed with the help of some auxiliary routines that are included in the AIRES library The machine and operating system used to generate such files may be different that the ones used to read them As mentioned previously the physical algorith
170. ical depth or altitude specifications Xa X In this second case the positions of the first and last observing levels are set accordingly with Xa and X with no dependence on the positions of the injection and ground levels xi min Xq Xo x max Xq Xp 3 10 The spacing between consecutive levels is evaluated using equation 2 19 64 CHAPTER 3 STEERING THE SIMULATIONS Site name Latitude Longitude Altitude m a s 1 Site00 0 00 0 00 0 SouthPole 90 00 S 0 00 3127 ElNihuil 35 20 S 69 20 W 1400 Millard 39 10 N 112 60 W 1400 AGASA 35 78 N 138 50 E 900 CASKADE 49 09 N 8 88 E 112 Dugway 40 00 N 113 00 W 1550 ElBarreal 31 50 N 107 00 W 1200 FlysEye 41 00 N 112 00 W 850 HaverahPark 53 97 N 1 64 W 220 Puebla 19 50 N 98 00 W 2200 SydneyArray 30 50 S 149 60 W 250 Yakutsk 61 70 N 129 40 E 850 Table 3 2 Predefined sites of the AIRES site library Site names are case sensitive The data for Haverah Park Sydney Array and Yakutsk sites come from reference 28 3 3 4 Geomagnetic field The components of the Earth s magnetic field used by the simulation programs can either be set manually or calculated with the help of the IGRF model 8 see section 2 1 5 With the help of this model it is possible to obtain an accurate estimation of the geomagnetic field in a given geographic location and for a determined date To activate this mechanism for automatic evaluation o
171. ile for example consists of a series of records of all the particles that reached ground in specified circumstances Thanks to the com pressed data formatting used it is possible to save a large number of particle records using a moderate amount of disk space The format is universal so the files can be writ ten by a given machine and processed in a different one The AIRES system includes a library of subroutines to process such files see section 4 2 Basic parameters A list of geometrical and physical shower parameters These variables define the initial conditions of the shower simulations primary particle axis inclination etc as well as the settings that are in effect for the parameters of the monitoring algorithms number of observing levels range of radial distances for output files etc Additional parameters Other shower parameters generally depending on the model used Since the interactions models are replaceable the type and number of additional parameters may 58 CHAPTER 3 STEERING THE SIMULATIONS vary when changing simulation programs The variables included in this section as well as the directives that allow controlling them may also be changed in future versions of AIRES By default only the most relevant parameters are listed Quantities associated with hidden IDL directives see appendix B are not included Nevertheless AIRES can be instructed to produce a full listing by means of the directive InputListin
172. illas thinning algorithm see section 2 3 1 and considering the representative case of 5 x 101 eV proton showers with 40 deg zenith angle it is easy to verify that the CPU time per shower scales linearly with log Eprimary thinning The CPU time per shower increases roughly in a factor of 8 when Eprimary Ethinning iS increased in one order of magnitude To give an estimation of the ab solute amount of time needed to simulate one shower it can be mentioned that in a Pentium II machine 300 Mhz clock using Linux OS the CPU time for a single shower with Eprimary Ethinning 10 is about 12 minutes This projects onto some 12 and 100 hours for 10 and 10 respectively The CPU time depends on other parameters besides the thinning and primary energies see section 2 3 3 The inclination of the shower axis zenith angle is one of them The CPU time per shower generally increases when the zenith angle is enlarged A 45 deg 85 deg inclined shower requires roughly 1 3 1 6 times more CPU time that a vertical one It is important to say that the algorithms that take into account the curvature of the earth and the effect of the geomagnetic field were designed in such a way that their CPU time requirements are not important when compared with the overall requirements of the simulating engine As a result the CPU time per shower needed to perform simulations using the current AIRES version 2 6 0 are essentially the same as the corresponding ones
173. in one of the PATH directories in other words if you type at your terminal say 77 the machine will take 77 as a known command If the compilers are not in the PATH 109 110 APPENDIX A INSTALLING AIRES AND MAINTAINING EXISTING INSTALLATIONS you will have to enter their absolute location manually in the config file Our recommendation however is to ensure that the compilers are in the PATH It is something not difficult to achieve If you do not know how to proceed or what we are speaking about then ask your local UNIX expert e The simulation program uses scratch files for internal data paging The scratch space needed for a run depends on the input parameters and the size of the internal particle stacks For ultra high energy hard thinned showers Primary energy greater than 1018 eV primary energy over thinning energy ratio greater than 10 and for a stack size of 5 MB the default a minimum of 15 20 MB scratch file space will be needed during the simulations This figure can be more than 100 MB for very heavy simulations If you want to reduce the scratch space requirements then you will have to lower the stack size modifying the corresponding parameter in file config A 1 1 Installation procedure step by step 1 Ensure that you have write permission on both Iroot and Aroot directories and in all their sub directories 2 cd to Iroot and edit the file config Set all the variables accordingly with the guideli
174. in the interval t 1 where t is a specified threshold 0 lt lt 1 It is necessary to initialize the random series calling raninit before using this function Arguments threshold Input double precision The threshold t Returned value Double precision The uniform pseudo random number 214 APPENDIX D THE AIRES OBJECT LIBRARY xslant FORTRAN X xslant Xvert Xv0 cozenith zground xslant amp Xvert amp Xv0 amp cozenith amp zground C X Converting vertical atmospheric depths into slant atmospheric depths This routine evaluates the slanted path in g cm of equation 2 8 starting ending at the point whose vertical depth is Xvert Xv0 The inclination of the integration path is controlled by parameters cozenith cosine of the zenith angle and zground altitude in meters of the intersection between the oblique axis and the z axis as illustrated in figure 2 1 page 12 Arguments Xvert Input double precision Vertical atmospheric depth in g cm of the point marking the beginning of the integration path Must be positive Xv0 Input double precision Vertical atmospheric depth in g cm of the point marking the end of the integration path If Xv0 is zero then the end of the integration path is the top of the atmosphere If Xv0 corresponds to a point located below the point corresponding to Xvert Xv0 gt Xvert then the returned slant depth will be negative cozenith Input double p
175. ined in page 172 For successful read operations irc indicates the record type that has been just read in O for the default particle record 1 2 for the beginning end of shower record etc At the same time the logical variable altrec distinguishes between alternative non default records true from default ones false The data stored in the different fields of the record is retrieved by means of the arrays indata and fidata Both are single index arrays containing integer and double precision data respectively The data items stored in these arrays does vary with the kind of file being processed and the type of record that was scanned In all cases the routine will automatically set the relevant elements of these arrays accordingly with the logical definition of the record regardless of the physical structure of it which remains absolutely hidden at the user s level To fix ideas let us suppose that a ground particle file with normal particle records is being pro cessed Every time ire is zero default record the integer and real data arrays will contain the elements listed in table 4 5 page 89 that is indata 1 lt Particle code fldata 1 lt Energy GeV log fldata 2 lt Distance from the core m log fldata 3 lt Ground plane polar angle radians fldata 7 lt Particle weight 98 CHAPTER 4 MANAGING AIRES OUTPUT DATA For different return codes the number of assigned array elements may
176. ion During this step the particle s coordinates direction of motion and energy can be altered The final step is to process the interaction itself This generally involves the creation of new par ticles secondaries which are added to the corresponding stacks and remain waiting to be processed and eventually the deletion of the current particle for example in the case of positron annihilation In some cases it is necessary to apply corrections to the probability distributions used to determine the particle s fate This happens with processes which have rapidly changing cross sections or by CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 25 120 Proton E 110 100 90 80 70 60 50 40 30 20 MEP g cm MEP g 10 10 10 107 10 Lab energy GeV 10 10 10 10 10 10 10 10 10 Lab energy GeV Nucleus energy GeV Figure 2 6 Hadronic mean free paths versus projectile energy lab system The solid blue and dashed red lines represent respectively the SIBYLL 2 1 and QGSJETOI models In the proton pion and kaon cases the mean free paths corresponding to the models SIBYLL 1 6 dot dashed green and QGSJET99 dotted cyan have been included for comparison The iron plot includes also the mean free paths evaluated using the AIRES built in algorithm in the SIBYLL dot dashed green and QGSJET dotted cyan cases 26 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES corrective processe
177. ion of them Log file taskname lgf This file contains information about the events that took place during the simulations It contains also a summary of the input parameters that were in effect Most of the data that goes into the log file is also written into the standard output channel Summary file taskname sry also taskname tex Output summary This includes general simulation data and all the tables that were printed using IDL directive PrintTables Exported data files askname tnnnn Plain text files containing output tables Task summary script file askname tss File containing a summary of input and output data written in a format suitable for processing with other programs Binary dump file askname idf This file contains in machine dependent binary format all the relevant simulation data This file is periodically updated during the task processing In the case of an interruption it is possible to restart the simulations from the last update The file is also useful to obtain relevant data after the simulation is completed or even during it This can be done with the help of the summary program AiresSry ASCII dump file askname adf Portable version of the IDF file written at the end of the task Like the IDF file this file can be processed with the summary program AiresSry Compressed output files taskname grdpcles and or taskname gtpcles These files contain detailed particle data The ground particle f
178. ip The amp must be the first non blank character in the line and all characters after label are treated as a comment label is a non null string which can contain any character excluding blanks and the comment character AddSite Syntax AddSite name lat long height d Appending a new site to the AIRES site library name is a string having no more than 16 characters and must be different to all the previously defined sites including the predefined entries listed in table 3 2 page 64 Site names are case sensitive lat and long are angle specifications defining respectively the geographic latitude and longitude of the site lat long must be in the range 90 90 180 180 height is a length specification defining the site s altitude above sea level The directive Site permits to select already defined locations AddSpecialParticle Syntax AddSpecialParticle pname module parstring d Adding a new definition to the list of special particles pname is a string having no more that 16 characters that uniquely identifies the special particle being defined module is the name of the executable module associated to the special particle The file module must exist in the current working directory or in one of the directories that were specified with directive InputPath Every time a new shower with primary pname starts the module module will be executed by the main simulation program to generate a list of stand
179. is always zero by construction since in the AIRES coordinate system the x axis points to the local magnetic north defined as the direction of the H component of the geomagnetic field There are two alternatives for specifying the geomagnetic field in AIRES i Manually entering F I and D ii Giving the geographical coordinates altitude and date of a given event In the later case the magnetic field is evaluated using the International Geomagnetic Reference Field IGRF 8 a widely used model based on experimental data that gives accurate estimations of all the components of the Earth s magnetic field We are not going to place here any further analysis of the geomagnetic field and its implementation in an air shower simulation program The interested reader can consult reference 17 which contains a detailed description of general aspects of the geomagnetic field and the IGRF together with a discussion about the practical implementation of the deflection procedure and an analysis of the effect of the geomagnetic field on several air shower observables 2 2 Air showers and particle physics We are going to describe here how the particles of an air shower are identified and processed and which interactions are taken into account 2 2 1 Particle codes AIRES recognizes all the particles commonly taken into account in air shower simulations plus ad ditional ones included for completeness Each particle is internally identified by a partic
180. is directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES MaxCpuTimePerRun Syntax MaxCpuTimePerRun time Infinite Default MaxCpuTimePerRun Infinite d This directive sets the maximum CPU time for individual runs being a run the processing chunk that goes between two consecutive updates of the internal dump file This parameter does not impose any restriction on the CPU time available for the simulation of a single shower or a group of them which is always infinite time is any valid time specification See also directives RunsPerProcess and ShowersPerRun MesonCutEnergy Syntax MesonCutEnergy energy Default MesonCutEnergy 60 MeV s Minimum kinetic energy for mesons pions kaons etc Every meson having a kinetic energy below this threshold is not taken into account in the simulation unstable particles are forced to decays energy must be greater than or equal to 500 keV 126 APPENDIX B IDL REFERENCE MANUAL MFPHadronic Syntax MEPHadronic mfpsel Default MFPHadronic SIBYLL MFPHadronic QGSJET for program Aires AiresQ s Directive to select among different sets of mean free paths parameterizations mfpsel is a character string that can take any one of the following values Standard SIBYLL OGSJET or Bartol Each alternative correspond to different parameterizations for the mean free path of hadron air and nucleus air collisions This directi
181. is enough to store all the data items nrealf Output integer array O nrtype Number of real fields contained at each record type for record types from zero to nrtype No check is made to ensure that the length of the array is enough to store all the data items irc Output integer Return code 0 means successful return 162 APPENDIX D THE AIRES OBJECT LIBRARY crorewind FORTRAN call crorewind channel vrb irc C crorewind amp channel amp vrb amp irc Rewinding an already opened compressed file The file is positioned just before the first data record In other words the file is system rewound and its header is re scanned so the file pointer remains located at the beginning of the record data stream Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 me
182. is going to be processed it will suffer one of several possible interactions J i 1 n n gt 1 To fix ideas let us consider the case of a positron The possible interactions J are annihilation interaction with an atom from the medium and emission of a knock on electron and emission of a bremsstrahlung photon 24 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES Evaluating the mean free paths Every interaction J is characterized by its cross section 0 or equivalently by its mean free path Ai A and g are connected via yoa ai 2 18 Ti where Mair is the mass of an atom of the medium the particle propagates trough that is an average atom of air in the case of air showers The usual units for are g cm The mean free paths do depend on the kind of interaction and on the particle s instantaneous pa rameters They can be calculated analytically for certain interactions in other cases they must be estimated by means of parameterization of experimental data and this generally requires extrapola tions out of the region corresponding to the measurements A typical example of this situation is the case of the mean free paths for inelastic collisions particle nucleus where particle can be proton gamma other nucleus etc Such mean free paths depend on the energy of the projectile particle and must be calculated for energies well above the maximum energies attainable in collider experiments Figure 2 6 cont
183. is used in tables 5000 to 5513 and in the beginning of shower and end of shower compressed file records for details see chapter 4 Forcelnit Syntax ForceInit On Off Default ForceInit is equivalent toForceInit On ForceInit Off is assumed in case of missing specification d If ForceInit is enabled then a new task is started at the beginning of every process If the corresponding IDF file exists then the task version is increased until an unused version is found This directive is useful for debugging purposes ForceLowEAnnihilation Syntax ForceLowEAnnihilation opt Default ForceLowEAnnihilation Normal ForceLowEAnnihilation with no specification is equivalent to ForceLowEAnnihilation Always s h Directive to control the action to take when processing a low energy particle that can anni hilate with its respective anti particle The variable opt can take the values Always Never or Normal The first two alternatives correspond respectively to the cases where the low energy particles will always be forced to annihilation or be discarded without producing any secondary particle In the default Normal option the action to take for annihilating low energy particles depends on the particle cut energy and mass If the cut energy is less greater than the rest gt The old AIRES 1 4 2 and older syntax is no longer supported 122 APPENDIX B IDL REFERENCE MANUAL mass then the particle is is not forced to annihi
184. itrons and muons muonic pair production knock on electrons 6 rays Compton and photoelectric effects Landau Pomeranchuk Migdal LPM effect and dielectric suppression ii Unstable particle decays pions and muons for instance iii Hadronic processes Inelastic collisions hadron nucleus and photon nucleus generally simulated using an external package which implements a given hadronic interaction model like the well known SIBYLL 6 or QGSJET 7 models or by a built in algorithm called extended Hillas splitting algorithm EHSA Photonuclear reactions Nuclear fragmentation elastic and inelastic iv Propagation of charged particles Losses of energy in the medium ionization multiple Coulomb scattering and geomagnetic deflections All the general characteristics of AIRES and the physics involved in air shower simulations are summarized in table 1 1 they are described in more detail in chapter 2 AIRES is completely written in standard FORTRAN 77 using a few extensions that are to the best of our knowledge accepted by all FORTRAN compilers The complete AIRES 2 6 0 source code which includes the QGSJET 7 and SIBYLL 6 hadronic collisions packages the IGRF 8 routines to evaluate geomagnetic data and Netlib minpack Imder nonlinear least squares fitting pack age 10 consists of more than 670 routines adding up to more than 94 000 source lines extensively commented In the present version the AIRES simulation system consists o
185. l their variants the AIRES version used to write it and or the machine used when writing it Getting information about the file The headers of the compressed files are divided into two parts One part containing the definitions of the file s data records and another section with information about the simulations that originated the file The file definitions are specific to each opened file and therefore the system must store them separately for each one of the files that are simultaneously open The other information however is of global character and so the available data always corre sponds to the last opened file These data are superseded each time opencrofile is called Routine croheaderinfo prints a summary of this global information while croinputdata0 copies some of those data into arrays to make them available to the user see page 154 and crotaskid returns task name information Functions getinpint getinpreal getinpstring and getinpswitch see pages 176 179 allow to obtain other input data items not returned by croinputdata0 getglobal can be called to retrieve information about global variables that were defined during the simulations idlcheck returns information about the IDL instructions that were valid when the file was generated and crofileversion and thisairesversion return version information that might be useful when reading compressed files written with old AIRES versions In some special applications it is necessar
186. l variables are imported by default d Setting global variables The variable varname is set to the string value If the variable was already set then its old setting is superseded The defined variables can either be used within the IDL input stream or passed to the compressed output files or special primary modules The Dynamic qualifier default indicates the dynamic character of the corresponding variable This means that the value currently passed to the external modules is modified each time AIRES is invoked for a given task On the other hand Static variables are set at the first invocation of AIRES and further settings have no effect SetTimeAtInjection Syntax SetTimeAtInjection On Off Default SetTimeAtInjection is equivalent to SetTimeAtInjection On SetTimeAtInjection On is assumed in case of missing specification s h Directive to set whether the time count for each shower is started at the moment of inject ing the primary particle On or at its first interaction Off This directive is ignored for showers initiated by special primaries see section 3 5 ShowersPerRun Syntax ShowersPerRun number Infinite Default ShowersPerRun Infinite d Maximum number of showers in a run see also MaxCpuTimePerRun and RunsPerPro 134 APPENDIX B IDL REFERENCE MANUAL cess Notice that this parameter is related with the computer environment only and does not affect the total number of showers that define a task see
187. lation ForceLowEDecays Syntax ForceLowEDecays opt Default ForceLowEDecays Normal ForceLowEDecays with no specification is equivalent to ForceLowEDecays Always s h Directive to control the action to take when processing a low energy unstable particle that can decay into other particles The variable opt can take the values Always Never or Normal The first two alternatives correspond respectively to the cases where the low energy particles will always be forced to decays or be dicarded without producing any secondary parti cle In the default Normal option the action to take for decaying low energy particles depends on the particle cut energy and mass If the cut energy is less greater than the rest mass then the particle is is not forced to decays ForceModelName Syntax ForceModelName modsel Default No model name check is performed when this directive is not used s This directive allows the user to force that a given input data set will be processed with the simulation program linked with the external collision package specified with modsel Currently modsel can be one of case dependent SIBYLL or QGSJET This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES GammaCutEnergy Syntax GammaCutEnergy energy Default GammaCutEnergy 80 KeV s Minimum energy for gammas Every gamma ray having an energy below this threshold is not taken into
188. lative level The width of the bands correspond to the average value plus and minus one RMS error of the mean shower as a function of Wy for various thinning energies The time unit is the average time required to complete a shower simulated with 1073 relative thinning and Wy gt oo The CPU time per shower increases monotonically when W decreases For any Ern and W 1 for example the required time is roughly 5 times larger than the one for Wy ov But it is 1 6 13 times lower than the one corresponding to the Hillas algorithm for Ey 10 Ern 100 These figures may represent an important time saving factor in certain circumstances for example when evaluating lateral distributions like the ones of figure 2 10 page 34 The use of the AIRES extended thinning algorithm with finite Wy is always recommended how CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 35 Ss 5 5 mI mI ml an3 Z z 10 Z 3 10 10 10 i 10 1 1 0 0 Figure 2 11 Effect of the AIRES extended thinning on the distribution of weights for different particles gammas electrons and positrons and muons The plots correspond to 2 x 10 eV proton showers simulated with Esn Eprim 1075 and different weight factors wg Wy Wt wih gg CPU time arb units gt N 10 Figure 2 12 Processor time requirements for the AIRES extended thinning algorithm plotted versus Wy wee Wt for ppi eee rere different relative thi
189. ld onto the ground plane shower front plane The data corresponds to a single 3 x 101 eV proton shower with a zenith angle of 60 degrees and random azimuth The environmental parameters correspond to the El Nihuil site located in Argentina see table 3 2 and the simulations were done with a 1078 thinning level and W 20 44 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES geomagnetic field on air shower observables The reader interested in a more detailed study of this subject can look up in reference 17 Chapter 3 Steering the simulations There are many parameters that must be specified before and during an air shower simulation job The Input Directive Language IDL is a part of the AIRES system and consists in some 70 human readable directives that permit an efficient control of the simulations in a comfortable environment The most common IDL directives are described in this chapter and many illustrative examples are discussed a detailed description of the IDL language is placed in appendix B page 114 It is recommended to properly install the software see appendix A before proceeding with the following sections 3 1 Tasks processes and runs The simulation of high energy air showers is a CPU intensive task which can demand days and even weeks of processor time to complete The AIRES program was designed taking this fact into account It includes an auto saving mechanism to periodically save into an internal dump fil
190. le code It is important to notice however that user level particle specifications are made by means of particle names instead of numeric codes Table 2 3 lists AIRES particle codes together with the corresponding particle names and syn onyms Nuclear codes are set taking into account Z atomic number N number of neutrons and A Z N mass number in a computationally convenient codification formula code 100 3274 N Z 8 2 17 with 0 lt N Z 8 lt 31 Taking 1 lt Z lt 26 from hydrogen to iron this coding system allows to uniquely identify all known isotopes Regarding the names of nuclei they can be specified in several ways i By their chemical names for example Fe 56 56 refers to the mass number A which defaults to the most abundant isotope s mass number when not specified ii By special names as Deuterium for H or Iron for Fe iii By direct specification of Z N and or A for example NZ 2 2 He ZA 26 54 Fe etc In certain cases it may be needed to refer to groups of particles having some properties in common There are several particle groups defined in the AIRES system which can be useful in such situations The most important groups of particles are listed in table 2 4 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 21 Particle Code Name and synonyms y 1 Gamma gamma er 2 e Positron positron e 2 e Electron electron u 3 mu Muon muon H 3 mu Muon muon TT 4
191. le file Amount of processor time required for the simulation of the current shower Table 4 2 continued 87 88 CHAPTER 4 MANAGING AIRES OUTPUT DATA Field Name Comment Integer 1 Particle code Stores the code of the corresponding pri mary particle Real 1 Energy GeV log The logarithm of the corresponding pri mary particle s energy 2 Direction of motion x component With respect to the AIRES coordinate system see page 11 3 Direction of motion y component 4 Direction of motion z component 5 X coordinate m Particle injection coordinate with re spect to the AIRES coordinate system see page 11 6 Y coordinate m 7 Z coordinate m 8 Injection depth g cm2 9 Injection time ns 10 Particle weight Initial statistical weight of the corre sponding particle Table 4 3 Fields contained in the external primary particle record of compressed particle files The structure of this record does not depend on the compile time option selected for the particle record Field Name Description Integer 1 Version of external module User settable integer in the range 0 759375 Real 1 Total number of primaries Total number of primary particles Unweighted primary entries Unweighted number of primary entries 3 Total energy of primary particles Total energy of primary particles GeV weighted Table 4 4 Fields contained in the special primary trailer record of compressed particle files The structure of
192. le kind and energy These two specifications together with other related ones permit a very wide range of specifica tions for the shower parameters Let us investigate some of the possible alternatives Mixed composition The primary particle needs not be unique AIRES allows for simulating showers with different pri mary particles each The following example illustrates this feature PrimaryParticle Proton 0 6 PrimaryParticle Iron 0 4 With such settings the primary will be proton iron with 60 40 probability This means that in 100 simulated showers approximately 60 will be proton showers while the remaining ones will have iron primaries If n alternative primary particles p i 1 n were defined with weights w w 0 then the probability for any shower of being initiated by particle pj 1 lt j lt nis given by ws Xaia w5 Therefore the weights entered in the IDL directives need not be normalized P 3 1 Besides this mixed composition feature AIRES allows also to define special primary particles processed by external modules For details see section 3 5 page 70 Varying energy The directive PrimaryEnergy Emin Emax 7 see page 129 indicates that the primary energies will be in the interval Emin Emax selected with probability 22 p E dE U BO dE Emin lt E lt Emax 3 2 where Bis gt Enh Erix y 0 U E O dE 3 3 Emin In Emax Emin J 0 y can take any value If
193. lear re APPENDIX B IDL REFERENCE MANUAL 129 actions from the gamma ray propagating algorithms The collisions are enabled by default Disabling them may lead to non realistic air shower simulations This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES PrimaryAzimAngle Syntax PxrimaryAzimAngle minang maxang Magnetic Geographic Default PrimaryAzimAngle 0 deg Magnetic if the zenith angle is fixed PrimaryAzimAngle 0 deg 360 deg Magnetic otherwise see PrimaryZenAngle s Primary azimuth angle The angle for each shower is selected with uniform probability distribution in the interval minang maxang If the angle maxang is not specified it is taken equal to minang fixed azimuth angle The Geographic keyword indicates that the specified azimuth is measured with respect to the geographic north positive for eastwards directions in this case the azimuth angle used by AIRES is obtained applying equation 3 8 If no keyword or the Magnetic keyword is specified then the origin for the azimuths is the magnetic north and the given angles are interpreted accordingly with the orientation of the AIRES coordinate system defined in section 2 1 1 page 11 PrimaryEnergy Syntax PrimaryEnergy minener maxener gamma Default None This directive is always required s Energy of primary If only minener is specified then all primaries have a fi
194. les The structure of this record does not depend on the compile time option selected for the particle record Energy The logarithm of the kinetic energy of the particle Coordinates The polar coordinates R y of the particle at ground measured from the intersection of the shower axis with the ground surface R is the distance to the core and y is the angle with respect to the x axis Direction of motion The x and y components uz Uy of the unitary vector u which indicates the particle s direction of motion The u component must be negative for the particles reaching ground because such particles move downwards It can be calculated via uz 4 1 u ud 4 2 86 Integer Real Field 1 3 8 1 CHAPTER 4 MANAGING AIRES OUTPUT DATA Name Shower number Xmax fit return code Ending date and time Total number of shower particles Total number of lost particles Number of low energy particles Number of particles reaching ground Total number of unphysical particles Total number of neutrinos Particles too near to the shower core Particles in the resampling region Description Shower number matching the shower number of the corresponding beginning of shower record Integer code returned by the Xmax and Nmax fitting routine described in section 4 1 page 77 Six fields containing respectively the year month day hours minutes and seconds corresponding to the end of t
195. level measured along the shower axis and unitary vector in the direction of the shower axis Besides these variables it is possible optionally to retrieve additional ones calling other routines included in the AIRES object library e speigetpars page 205 returns the parameter string that can be optionally specified in the IDL instruction that defines the corresponding special particle see directive AddSpe cialParticle page 115 The simulation program passes the argument string directly without making any special processing on it e speigetmodname page 204 returns the name of the executable module specified in the definition of the corresponding special particle e sprimname page 211 returns the name of the special particle corresponding to the cur rent invocation of the external module e speitask page 209 returns the current task name e spnshowers page 210 returns three integers that correspond respectively to the total number of showers assigned to the task and the numbers of the first and last showers These quantities are related to the specifications entered with the directives TotalShowers and FirstShowerNumber The variable shower_number set when calling speistart see figure 3 3 will always be equal or larger smaller than the first last shower number Adding primary particles to the primary particle list Routine spaddp0 appends to the particle list the particle defined with the arguments used in the corr
196. lity to use the Simulation System including but not limited to loss of data or data being rendered inaccurate or losses sustained by the user or third parties or a failure of the System to operate with any other programs even if the author s have been advised of the possibility of such damages Product and company names mentioned in this manual are trademarks or trade names of their respective companies Summary The name AIRES AIR shower Extended Simulations identifies a set of programs and subroutines to simulate particle showers produced after the incidence of high energy cosmic rays on the Earth s atmosphere and to manage all the related output data AIRES provides full space time particle propagation in a realistic environment where the char acteristics of the atmosphere the geomagnetic field and the Earth s curvature are taken into account adequately A statistical sampling procedure the so called thinning is used when the number of par ticles in the showers is exceedingly large The thinning algorithms used in AIRES are unbiased that is the statistical sampling never alters the average values of output observables The particles taken into account by AIRES in the simulations are Gammas electrons positrons muons pions kaons eta mesons lambda baryons nucleons antinucleons and nuclei up to Z 36 Electron and muon neutrinos are generated in certain processes decays and accounted for their energy but not propagat
197. ls Syntax RecordObsLevels Not Zev lev2 step RecordObsLevels Not All Al1 step None Default RecordObsLevels All s Directive to mark a certain subset of the defined observing levels for inclusion or exclusion in the set of levels that are included in the longitudinal tracking compressed particle file The integer variables lev1 lev2 and step are the arguments of a FORTRAN do loop which starts at lev1 ends at lev2 advancing in steps of step The keyword Not indicates that the corresponding levels must be excluded for being recorded in the file If lev2 and or step are not indicated they default to levI and 1 respectively RecordObsLevels All step is a short form for RecordOb sLevels 1 XV step where No is the number of defined observing levels RecordObsLevels All is equivalent to RecordObsLevels All 1 while RecordObsLevels None can be used in place of RecordObsLevels Not All This directive can be repeatedly used within an input instruction stream to mark or unmark arbitrary subsets of observing levels as explained in page 93 Remark Syntax Remark string Remark amp label First line of remarks Last line of remarks amp label s Remarks directive Each time this directive appears in the input data stream the correspond gt This is not supported for IDF files generates with AIRES versions previous to version 2 0 0 132 APPENDIX B IDL REFERENCE MANUAL ing remark string s are appended to the remarks text
198. lude exclude the hadronic inelastic collisions with air nucleus from the heavy particles propagating algorithms The collisions are enabled by default Disabling them may lead to non realistic air shower simulations This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES NuclCutEnergy Syntax NuclCutEnergy energy Default NuclCutEnergy 120 Mev s Minimum kinetic energy for nucleons and nuclei Every such particle having a kinetic energy below this threshold is not taken into account in the simulation energy must be greater than or equal to 500 keV 128 APPENDIX B IDL REFERENCE MANUAL ObservingLevels Syntax ObservingLevels nofol altdepth1 altdepth2 Default ObservingLevels 19 s This directive defines the number and position of the observing levels used for longitudinal development recording see page 26 altdepthI and altdepth2 are altitude or atmospheric depth specifications that define the positions of the first and last observing levels nofol is an integer that sets the number of observing levels It must lie in the range 4 510 The observing levels are equally spaced in atmospheric depth units The first last level corresponds to the highest lowest altitude If altdepth1 and altdepth2 are not specified then the observing levels are placed between the injection and ground planes but spacing them differently see section 3 3 3 The injecti
199. ludes a new section namely cerntools consisting of a series of PAW macros capable of downloading AIRES output data directly from within this analysis program 15 The installation procedure includes a new platform option ALPHA workstations with Linux OS 16 The compiling options for DEC ALPHA and HP workstations were modified to overcome some compiling and running problems that were present in past releases of AIRES 17 Additionally lots of minor changes improvements and of course corrections of bugs AIRES version 1 4 2a 18 Aug 1998 This version is functionally similar to version 1 4 2 The code incorporates corrections to some minor bugs AIRES version 1 4 2 18 Jun 1998 This version of AIRES consists of about 450 routines adding up to more than 66 000 lines of source code APPENDIX F AIRES HISTORY 225 Features 1 The User s Manual was revised and expanded The summary and introduction were completely rewritten In particular a more precise description of the relation existing between AIRES and MOCCA was made 2 The LPM effect algorithms were completely rewritten The new procedures emulate Migdal s theory including the effect of dielectric suppression The old routines were not correct the errors were inherited from MOCCA s procedures and therefore it is recommended to re run simulations done with older versions of AIRES at primary energies larger than 1018 eV 3 The number of observing levels to b
200. m the injection point to the intersection between the shower axis and the ground surface in meters uprim Output double precision array 3 Unitary vector in the direction of the straight line going from the injection point towards the intersection between the shower axis and the ground plane APPENDIX D THE AIRES OBJECT LIBRARY 209 speitask FORTRAN call speitask taskn tasklen tver C speitaskc amp taskn amp tasklen amp tver Getting the current task name and version This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments taskn Output string Task name The calling program must ensure there is enough space to store the string tasklen Output integer Length of task name tver Output integer Task name version 210 APPENDIX D THE AIRES OBJECT LIBRARY spnshowers FORTRAN call spnshowers totsh firstsh lastsh C spnshowers amp totsh amp firstsh amp lastsh Getting the current values of the first and last shower and total number of showers This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments totsh Output integer Total number of showers for the current task firstsh Output integer Number of first shower lasttsh Output integer Number of last shower APPENDIX D THE AIRES OBJECT LIBRARY 211
201. ma rays Low energy electrons Low energy positrons Low energy muons Low energy muons Other charged low egy pcles Other neutral low egy pcles Low energy e and e Low energy mu and mu All low energy charged pcles All low energy neutral pcles All low energy pcles Energy of low egy gamma rays Energy of low egy electrons Energy of low egy positrons Energy of low egy muons Energy of low egy muons Egy of other charged low egy pcles Egy of other neutral low egy pcles Energy of low egy e and e Energy of low egy mu and mu Egy of all low egy charged pcles Egy of all low egy neutral pcles Egy of all low energy pcles Energy deposited by gamma rays Energy deposited by electrons Energy deposited by positrons Energy deposited by muons APPENDIX C OUTPUT DATA TABLE INDEX 228 229 230 231 232 233 234 235 Code 7808 7891 7892 7905 7907 7991 7992 7993 Table name Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development 143 Energy deposited by muons Egy deposited by other charged pcles Egy deposited by other neutral pcles Energy deposited by e and e Energy deposited by mu and mu Egy deposited by all charged pcles Egy deposited by all neutral pcles Energy deposited by all pcles
202. miliar with the contents of the previ ous section describing the ground particle file before proceeding to read the present section We shall limit here to briefly describe only those aspects that are somehow different in both files The longitudinal tracking particle file contains records storing detailed information about the particles that cross the defined observing levels Since the observing levels are generally located at The expression of the acceptance probability is inspired in a suggestion by P Billoir 31 CHAPTER 4 MANAGING AIRES OUTPUT DATA 91 Field Name Short Norm Norm Long Extra a b long Integer 1 1 1 1 1 Particle code 2 2 2 Observing levels crossed Real 1 1 1 Energy GeV log 1 2 2 Direction of motion x component 2 3 3 Direction of motion y component 1 2 3 4 4 Particle weight 2 3 4 5 5 Crossing time delay ns 3 4 5 6 6 X coordinate m 4 5 6 7 7 Y coordinate m 8 Particle creation depth g cm2 9 Last hadronic interaction depth g cm2 Table 4 6 Fields contained in the particle records of compressed longitudinal tracking particle files The field numbers for the different particle records selectable at compilation time see text named short normal a normal b long and extra long records are tabulated Notice that a given field can have different field numbers altitudes that include the shower maximum and due to the fact that a single particle can cross more
203. mple plots displayed in figure 2 10 page 34 The outstanding characteristic of these plots is the fact that the density fluctuations diminish 32 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 100000 mT 100000 og ory mS a 4 10000 ir J 10000 Ta N a 1000 i S 1000 2 100 100 hy amp 10 4 amp 10 z l z a a i A b 0 1 L fi fi fi fi il 0 1 L fi fi fi fi L 50 100 1000 50 100 1000 R m R m 100000 L T T T T T va 100000 L T T T T T T lt N S N 10000 KS J 10000 KN g v E 1000 w 1000 ha J 2 K z 100 100 S gt 10 J 2 10 ke F 1 i F 1 E c kS a 0 1 C L fi fi L 24 0 1 L fi fi L L ka 50 100 1000 50 100 1000 R m R m Figure 2 8 Effect of the thinning energy on the fluctuations of the lateral distribution of electrons and positrons in the same conditions as in figure 2 7 when the weight factor w Wy is lowered In the particular cases of Wy 1 and Wy 0 5 the fluctuations corresponding to the 1075 relative thinning are of the order of the ones corresponding to the 1077 Hillas algorithm case yellow band which were plotted in all cases for reference Looking at the distributions of weights displayed in figure 2 11 page 35 it is possible to under stand the action of the weight limiting mechanism The distributions labeled nl blue lines corre spond to
204. ms of the MOCCA simulation program developed CHAPTER 1 INTRODUCTION 3 by A M Hillas 1 were used as the primary reference in the original design of AIRES As a result the output data coming from MOCCA SP 1996 mocorbin_zg and AIRES first version 1 2 0 2 are similar when both programs are invoked with equivalent initial conditions The particles taken into account by AIRES in the simulations are Gammas electrons positrons muons pions kaons eta mesons lambda baryons nucleons antinucleons and nuclei up to Z 36 Electron and muon neutrinos are generated in certain processes decays and accounted for their energy but not propagated The primary particle can be any one of the already mentioned particles with energy ranging from less than 1 GeV up to more than 1 ZeV 107 eV It is also possible to simulate showers initiated by special primary particles via a call to a user written module capable of processing the first interaction of the primary and returning a list of standard particles suitable for being processed by AIRES A detailed description on how to define and use special primaries is placed in section 3 5 Among all the physical processes that may undergo the shower particles the most important from the probabilistic point of view are taken into account in the simulations Such processes are i Electrodynamical processes Pair production and electron positron annihilation bremsstrahlung electrons pos
205. n Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Antiprotons Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution Lateral distribution 139 Gamma rays Electrons Positrons Muons Muons Pions Pions Kaons Kaons Neutrons Protons Nuclei Other charged pcles Other neutral pcles e and e Lateral distribution mu and mu pit and pi K and K All charged particles All neutral particles All particles GGG Goeeeqeqeqeqeceqcaeca Cc nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution nweighted lateral distribution Gamma r
206. ndicator 1 if the particle is going upwards 1 other wise firstol Output integer First observing level crossed 1 lt firstol lt 510 lastol Output integer Last observing level crossed 1 lt lastol lt 510 APPENDIX D THE AIRES OBJECT LIBRARY 193 olcrossedu FORTRAN call olcrossedu olkey ux uy uz firstol lastol C olcrossedu amp olkey amp ux amp uy amp uz amp firstol amp lastol This routine is similar to olcrossed but retrieves the information about the particle s direction of motion up or down in the form of an unitary vector Arguments olkey Input integer Key with information about the crossed observing levels See routine olcrossed ux uy Input double precision x and y components of the unitary vector marking the parti cle s direction of motion uz Output double precision z component of the direction of motion Positive means up wards motion firstol Output integer First observing level crossed 1 lt firstol lt 510 lastol Output integer Last observing level crossed 1 lt lastol lt 510 194 APPENDIX D THE AIRES OBJECT LIBRARY olsavemarked FORTRAN ismarked olsavemarked obslev vrb irc C ismarked olsavemarked amp obslev amp vrb amp irc Logical function returning true if an observing level is marked to be saved into longitudinal files false otherwise An arbitrary subset of the defined observing levels can be selected for
207. ne should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments mn Output string Name of external module The calling program must ensure there is enough space to store the string mnlen Output integer Length of external module name mnfull Output string Full name of external module Will be different of mn if the module was placed within one of the directories specified with the InputPath directive The calling program must ensure there is enough space to store the string mnfullen Output integer Length of full external module name APPENDIX D THE AIRES OBJECT LIBRARY 205 speigetpars FORTRAN call speigetpars parstring pstrlen C speigetparsc amp parstring amp pstrlen Getting the parameter string specified in the IDL instruction that defines the corresponding special particle This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments parstring Output string Parameter string The calling program must ensure there is enough space to store the string pstrlen Output integer Length of parameter string Zero if there are no parameters 206 APPENDIX D THE AIRES OBJECT LIBRARY speimv FORTRAN call speimv mvnew mvold C speimv amp mvnew amp mvold Setting and or getting the external macro version This routine should be
208. nes therein placed and with your needs It is mandatory to select one and only one platform If none of the specified platforms match your machine then you should try using the most adequate one continuing with the installation procedure and seeing what happens Save the file and leave the edit session when finished 3 Enter the command doinstall 0 if you are installing AIRES for the first time or doinstall 1 if you are upgrading your current installation This is the case for those users that are already employing a previous version of AIRES Note that you must not erase any existing installation of AIRES before completing the upgrade This procedure will install the software using the data you set in step 2 This may take some minutes to complete A message will be typed at your terminal indicating whether the in stallation was successful or not If you get any error message s you should check all the requirements described previously in particular points d and 1 Try also modifying the config file APPENDIX A INSTALLING AIRES AND MAINTAINING EXISTING INSTALLATIONS 111 4 Type the command case sensitive Aires to see if the program is running and is in your search path You should see typed at your terminal something like the following text gt gt gt gt gt gt gt gt This is AIRES version V V V dd Mmm yyyy gt gt gt gt Compiled by gt gt gt gt USER uuuuu HOST hhhhhhh DATE dd Mmm yyyy
209. nformation in the summary output file Summary Syntax Summary On Off Default Summary is equivalent to Summary On Summary On is assumed in case of missing specification d Directive to enable or disable the output summary APPENDIX B IDL REFERENCE MANUAL 135 TableIndex Syntax TableIndex On Off Default TableIndex is equivalent to TableIndex On TableIndex Off is assumed in case of missing specification d Directive to instruct AIRES to print a table index in the summary output file TaskName Syntax TaskName Append faskname taskversion Default TaskName GIVE_ME_A NAME PLEASE d Task name assignment taskname is a character string which identifies the current task If its length is greater than 64 characters it will be truncated to the first 64 characters taskversion is an optional integer between 0 default and 999 If taskversion is not zero the effective task name is taskname_taskversion If the keyword Append is used then taskname is appended to the existing task name string The task name is used to set the file names of all output files ThinningEnergy Syntax ThinningEnergy energy number Relative Default ThinningEnergy 1 0e 4 Relative s Thinning energy It can be expressed either as an absolute energy or as a real positive number with the keyword Relative In this case the thinning energy is the primary energy times the specified number ThinningWFactor Syntax ThinningWFactor
210. ng containing the parameters passed to the module The calling program must provide enough space for this string sppl Output integer Length of string sppars APPENDIX D THE AIRES OBJECT LIBRARY 165 crospnames FORTRAN call crospnames nspp spname C crospnamesc amp nspp amp spname 1 Retrieving the names of the currently defined special particles When this routine is used to re trieve information stored in a compressed file the data returned correspond to the most recently opened compressed file Arguments nspp Input integer The number of special particles defined spname Output string array Array containing the names of the defined particles The calling program must provide enough space for this array and its elements maximum 16 characters each 166 APPENDIX D THE AIRES OBJECT LIBRARY crotaskid FORTRAN call crotaskid taskname tasknamelen taskversion startdate C crotaskidc amp taskname amp tasknamelen amp taskversion amp startdate Getting task name and starting date for the task corresponding to the most recently opened compressed file Arguments taskname Output string The task name The calling program must ensure there is enough space to store the string tasknamelen Output integer Length of task name tasknameversion Output integer Task version startdate Output string Task starting date in the format dd Mmm yyyy hh mm ss 20 characters APPENDIX D
211. ng predeter mined observing levels Table 1 1 Main characteristics of the AIRES air shower simulation system CHAPTER 1 INTRODUCTION 5 the interfaces with the hadronic collision packages SIBYLL 2 1 QGSJETO1 SIBYLL 1 6 and QGSJET99 respectively e The summary program AiresSry designed to process a part of the data generated by the simulation programs allowing the user to analyze the results of the simulation after completing it or even while it is being run e The IDF to ADF file format converting program AiresIDF2ADF e A library of utilities to help the user to process the compressed output data files generated by the simulation program write external modules to process special primaries etc In UNIX environments this library is implemented as an object library called libAires a e The AIRES runner system A set of shell scripts to ease working with AIRES in UNIX envi ronments e A series of PAW 11 macros capable of downloading AIRES output data directly from within this analysis program 1 1 Structure of the main simulation programs An air shower starts when a cosmic particle reaches the Earth s atmosphere and interacts with it In most cases the first interaction is an inelastic collision of the high energy primary particle with an air nucleus The product of this collision is a set of secondary particles carrying a fraction of the primary s energy These secondaries begin to move through the atmosphere and
212. ng system that the user wants to work with It is possible to select either the AIRES coding system already described in section 2 2 1 page 20 or other usual coding systems The coding systems known by AIRES 2 6 0 are the following 1 Aires internal coding 2 Aires coding for elementary particles and decimal nuclear codes A 100 Z 3 Particle Data Group coding system 32 extended with decimal nuclear codes A 10 Z 4 CORSIKA simulation program particle coding system 30 5 GEANT particle coding system 33 6 SIBYLL 6 particle coding system extended with decimal nuclear codes A 100 Z 7 MOCCA style particle codes 1 extended to match all AIRES particles gt The codes corresponding to elementary particles are listed in table 4 7 8 Actually MOCCA does not use particle codes Instead particles are identified by types 1 gamma 2 electron 3 muon etc and charge 0 1 etc Our MOCCA style codes emulate this coding system generating particle codes by joining the sign of the charge and the particle type CHAPTER 4 MANAGING AIRES OUTPUT DATA Particle 3 3 B B SI AIRES PDG CORSIKA GEANT SIBYLL 1 22 11 11 13 13 15 15 12 12 14 14 16 16 111 211 211 310 130 321 321 221 2112 2112 2212 2212 ao ow N 87 66 67 68 69 Oo o N 10 11 12 17 13 25 14 15 Codes a ow wv 87 Oo N 10 11 12 17 13 25 14 15 ao FW N
213. ng system used is the one defined when starting the cio system shprimwt Output double precision array For i from 1 to intdata 1 shprimwt i gives the corresponding primary particle weight This weight is 1 in the single primary case 3Measured vertically starting from the intersection point between the sea level and the line that goes form the Earth s center to the particle injection point i e Zy in figure 2 1 The magnetic fluctuation parameter fp must be interpreted as follows When positive it gives the absolute fluctuation in nT Otherwise it indicates a relative fluctuation specification being AB f gt F 156 APPENDIX D THE AIRES OBJECT LIBRARY crooldata FORTRAN call crooldata vrb nobslev olzv oldepth irc C crooldata amp vrb amp nobslev amp olzv 1 amp oldepth 1 amp irc Calculating observing levels information from data contained in a compressed data file header Since the header data is of global nature the data used by this routine corresponds to the most recently opened compressed file Arguments vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb
214. ng the simulation and is the key for system fault tolerant processing since it makes it possible to restart a broken simulation process from the last update of the IDF The kernel interacts also with other modules that generate the output data namely log summary and task summary script files internal dump file in either binary or ASCII portable format and compressed output files generated by the monitoring routines and the particle data output unit In the current version of AIRES there are two compressed output files implemented The ground particle file and the longitudinal tracking particle file Records within the ground particle file longitu dinal tracking file contain data related with particles reaching ground level passing across observing levels Since the number of data records contained in such files can be enormous a special compression mechanism has been developed to reduce file size requirements The compressing algorithm is part of the particle data output module To give an idea of the space needed to store the particle records let us consider the case of the ground particle file with its default settings For each particle reaching ground and fulfilling certain user settable conditions a 18 byte long record is written The record data items are particle identity statistical weight position time of arrival and direction of motion Leading and trailing records are written before and after an individual shower is com
215. nge AIRES diagnostic messages always include a brief explanation about the circumstances that gen erated the message together with the name of the routine that originated it The messages can be classified in four categories accordingly with their severity i Informative messages are used to notify the occurrence of certain events and are generally associated with successfully concluded op erations ii Warning messages Used to put in evidence certain not completely normal situations In general processing continues normally iii Error messages indicate abnormal events like invalid input directives etc as illustrated in the previous example iv Fatal messages are issued when a serious error takes place in this case the program stops The IDL instruction set includes some directives that allow checking a given input data set Let us assume that the input directives are saved into a file named myfile inp Let us consider also that this file contains the instructions of the first example previously considered The instruction set Trace CheckOnly Input myfile inp End if processed by AIRES will generate an output similar to the following 0 0002 CheckOnly 0 0003 Input myfile inp 1 0001 Task a_first_example 1 0002 Primary proton 1 0003 PrimaryEnergy 150 TeV 1 0004 TotalShowers 3 1 0005 End 0 0004 End gt The primary energy must be greater than 500 MeV see page 129 48 CHAPTER 3 STEERING THE SIMULA
216. ngle file On the other hand groups of showers can be saved into separate files up to the limit of storing each shower in a different file see page 133 Compression rate The data compression algorithms were designed to take profit of the physical properties of the quantities being stored This involves information about lower and upper bounds for a variable possibility of subtracting a given fixed value etc Precision requirements were also taken into account imposing a minimum of five significant figures in most cases To give an idea of the size of compressed records let us consider the default ground particle record see below whose fields are Particle code logarithm of the energy logarithm of the distance to the core polar angle in the ground plane arrival time x and y components of the direction of motion and statistical weight This record thus has one integer field and six real ones and its length is 18 characters bytes This figure should be contrasted with a standard FORTRAN internal write statement with single precision for real variables which generates 28 data bytes when writing the same fields Taking into account that such records usually include additional formatting fields the compression rate of AIRES algorithm compared with standard unformatted FORTRAN i o should be larger than 36 It is worthwhile mentioning the the AIRES package includes a library of subroutines namely the AIRES object library which contai
217. nning 1 10 10 10 levels All cases correspond t to 10 eV proton showers 36 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES ever Even in the least favorable cases it is possible to get smoother distributions for every observable setting W not larger than 20 and thus eliminating the particle entries with unacceptably large weights 2 4 Some typical results obtained with AIRES The last section of this chapter is dedicated to present some illustrative results coming from air shower simulations made with AIRES using typical initial conditions Let us consider first the longitudinal development of showers started at the top of the atmosphere As mentioned in section 1 1 page 5 the number of particles in a shower increases initially then reaches a maximum and finally the shower attenuates as far as an increasing number of secondaries are produced with energies too low for further particle generation This characteristic behavior is illustrated in figure 2 13 which contains plots of the longitudinal development for all particles gam mas electrons and positrons muons pions and kaons The data used in this figure corresponds to an average over 75 vertical 300 EeV proton showers The plots of figure 2 13 also show us that the gammas are the most numerous particles crossing the observing levels placed near the shower maximum The electromagnetic shower gammas electrons and positrons accounts nearly for all the particles in the sho
218. not specified it is taken as 1 7 62 CHAPTER 3 STEERING THE SIMULATIONS Zenith and azimuth angles The zenith angle directive placed in the example of figure 3 1 page 51 corresponds to setting the an gle to a fixed value In this case the azimuth angle defaults to zero On the other hand the instruction PrimaryZenAngle 0 deg 72 deg S indicates that the zenith angle distributes from 0 to 72 with sine distribution Pa O d0 U sinO dO Omin lt O lt Omax 3 4 where U l i sin dO cos Omin COS Omax 3 5 An alternative to the S specification is the SC or CS specification which corresponds to a sine cosine distribution Pincos dO U sin O cos O dO Omin lt O lt Omax 3 6 where 5 U 7 sin 20 dO i cos 20min cos 2Omax 3 7 Omin For varying zenith angles the default for the azimuth angle is to uniformly distribute in the interval 0 360 In this case the sine distribution corresponds to showers with directions having a uniform solid angle distribution The azimuth angle can also be set as a varying angle The directive PrimaryAzimAngle 37 2 deg 39 5 deg indicates that the azimuth will be uniformly distributed in the interval 37 2 39 5 Using simultaneously instructions for both the zenith and azimuth angles it is possible to simulate showers coming from a determined direction in the celestial sphere As pointed out in section 2 1 1 page 11 the
219. ns many routines to read and process the compressed output It is possible to store up to 759375 showers in a single compressed file This refers to internal operations which do not alter any user level results 84 CHAPTER 4 MANAGING AIRES OUTPUT DATA files Backwards compatibility is always ensured Old compressed files generated with any previous version of AIRES can be read normally using the library routines 4 2 1 Customizing the compressed files Two kinds of compressed files are implemented in the current version of AIRES 2 6 0 Ground particle file Extension grdpcles This file contains records with data of particles that reached the ground surface Longitudinal tracking particle file Extension lgtpcles Compressed file containing detailed data related with particles crossing the predefined observing levels see section 2 2 3 Ground particle file There are three basic types of data records in this file Beginning of shower record end of shower record and particle record also referred as default record The external primary particle and spe cial primary trailer record are also defined These last two records are used only in connection with the special primary particles described in section 3 5 page 70 All the particle records written out during the simulation of a single shower will appear in the file preceded by a beginning of shower record and followed by the corresponding end of showe
220. nstructions ii Set up the external program that will be invoked via a system call at the moment of starting a new showers 3 5 1 Defining special particles 29 66 The AIRES IDL directives allow to specify particles by names proton gamma etc The set of known particle names can be expanded to include those special particles which need to be treated separately Consider the following examples AddSpecialParticle myparticX Xpartsim AddSpecialParticle myparticY xXpartsim type Y The IDL directive AddSpecialParticle takes at least two arguments i A special particle name that uniquely identifies the added special particle and ii The name of the executable module that will be invoked when starting the showers initiated by the respective particles In the preceding example two special particles namely myparticX and myparticY are defined and associated to the same external module Xpartsim In the case of the definition of myparticY some arguments are specified type Y Such arguments are passed portably to the module Once the special particle s are defined their names can be used as argument of the Primary Particle directive AddSpecialParticle myparticX Xpartsim PrimaryEnergy 20 EeV PrimaryParticle myparticxX Up to ten different special particles can be defined for a given task 72 CHAPTER 3 STEERING THE SIMULATIONS Special particles can also be used in the case of mixed composition
221. nt character which defaults to but can be changed by means of the directive CommentCharacter see page 117 In the last example the energy distributions 2791 2792 and 2793 are exported The option M indicates that energies must be expressed in MeV the default is GeV while L indicates that the cor responding data are normalized to dN dlog 9 E distributions The alternative option l corresponds to dN d1n E normalization To process the preceding code it might be useful to edit a small text file containing them and then use for instance the summary program to process it AiresSry lt myfile inp The files mytask t1205 mytask t1207 etc will be created If such files already exist they will be overwritten If the simulations that generated the data being processes were run with the PerShowerData op tion Full see section 3 3 6 then it is possible to export single shower tables by placing the directive The options IL were not supported in AIRES 1 2 0 CHAPTER 4 MANAGING AIRES OUTPUT DATA 81 ExportPerShower together with the ExportTables one s Returning to our previous example if such directive is placed inside the file myfile inp then for each one of the exported tables the files mytask tannn mytask_s0001 tannn mytask_s0002 tnnnn will be created corresponding respectively to the usual average table and the tables for shower 1 2 etc 4 1 3 The task summary script file The task summary scri
222. ntax Prompt On Off Default Prompt is equivalent to Prompt On Prompt Off is assumed in case of missing specification d Turns prompting on off This directive is meaningful only in interactive sessions PropagatePrimary Syntax PxropagatePrimary On Off Default PropagatePrimary is equivalent to PropagatePrimary On PropagatePrimary On is assumed in case of missing specification s h This directive controls the initial propagation of the primary If the On option is selected the default then the primary is normally advanced before the first interaction takes place and APPENDIX B IDL REFERENCE MANUAL 131 therefore the first interaction altitude will be variable Otherwise the first interaction will be forced to occur at the injection altitude This directive is ignored for showers initiated by special primaries see section 3 5 RandomSeed Syntax RandomSeed seed RandomSeed GetFrom idfile Default RandomSeed 0 0 s This directive sets the random number generator seed seed is a real number If it be longs to the interval 0 1 then the seed is effectively taken as the given number Otherwise it is evaluated internally using the system clock The alternative syntax with the keyword GetFrom allows extracting the random generator seed from an already existing internal dump file This is most useful to reproducing a previous simulation repeating the original random number simulator configuration RecordObsLeve
223. nteger The number of protons in the nucleus n Output integer The number of neutrons in the nucleus a Output integer The mass number APPENDIX D THE AIRES OBJECT LIBRARY 191 olcoord FORTRAN call olcoord nobslev olzv groundz injz zenith azimuth xaxis yaxis zaxis tshift mx my irc C olcoord amp nobslev amp olzv 1 amp groundz amp injz amp zenith amp azimuth amp xaxis 1 amp yaxis 1 amp zaxis 1 amp tshift 1 amp mx 1 amp my 1 amp irc This routine evaluates the coordinates of the intersections of observing level surfaces with the shower axis Zoi Yor Zoi 2 1 No the corresponding time shifts to and the coeffi cients Mgi Myi of the plane tangent to the surface at the intersection point Z Zoi Mgi T Loi Myi y you i 1 No D 2 Arguments nobslev Input integer The number of observing levels Wo olzv Input double precision array nobslev Altitudes in m of the corresponding ob serving levels groundz Input double precision Ground altitude in m injz Input double precision Injection altitude in m zenith Input double precision Shower zenith angle deg azimuth Input double precision Shower azimuth angle deg xaxis yaxis zaxis Output double precision array nobslev Respectively oi yo and Zois 1 1 No coordinates in m of the intersection points between the observing level surfaces and the show
224. nts wdir Input character string The name of the directory where the file is placed It defaults to the current directory when blank filename Input character string The name of the file to open header1 Input integer Integer switch to select reading greater than or equal to 0 or skip ping less than 0 the first part of the header logbase Input integer Variable to control the logarithmically scaled fields of the file records If logbase is less than 2 then the returned logarithms will be natural logarithms Other wise base logbase will be returned decimal ones if logbase 10 vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place channel Output integer File identification This variable should not be changed by the calling program It must be used as a parameter of the reading and closing routines in order to specify the corresponding file irc Output integer Return code O means successful return 1 means successful return obtained with a file that was written with a previous A
225. o account for all inclinations Realistic atmosphere Linsley model Geomagnetic deflections The geomagnetic field can be calculated us ing the IGRF model 8 Propagation general Medium energy losses ionization Scattering of all charged particles including corrections for finite nu clear size Geomagnetic deflections Propagation Electrons and Compton and photoelectric effects gammas Bremsstrahlung and ete pair production Emission of knock on electrons Positron annihilation LPM effect and dielectric suppression Photonuclear reactions Propagation Muons Bremsstrahlung and muonic pair production Emission of knock on electrons Decay Propagation Hadrons and Hadronic collisions using the EHSA low energy and QGSJET or nuclei SIBYLL high energy Nuleus nucleus collisions via QGSJET or SIBYLL or using a built in nuclear fragmentation algorithm Hadronic cross sections are evaluated from fits to experimental data low energy or to QGSJET or SIBYLL predictions high energy Emission of knock on electrons Decay of unstable hadrons Statistical sampling Particles are sampled by means of the Hillas thinning algorithm 4 extended to allow control of maximum weights Main observables Longitudinal development of all particles recorded in up to 510 observ ing levels Energy deposited in the atmosphere Lateral energy and time distributions at ground level Detailed list of particles reaching ground and or crossi
226. of version 1 2 0 even for showers with large zenith angles where the spherical earth calculations become important 12 Memory requirements depend basically upon the size of the stack area set at compilation time With the default area size of 5 MB Megabytes the program uses about 9 MB of random access memory Disk storage requirements depend on the stack area size thinning level and for the output compressed files on the number and kind of showers to be simulated Internal procedures create some scratch files whose size can be as large as several tens of MB The size of the largest scratch files is directly correlated to the total number of processed particles In figure 1 2 the number of processed particles is plotted versus the thinning level It is evident that the processed particles and hence the hard disk space requirements grows significantly when the thinning energy is lowered 1 3 Getting and installing AIRES AIRES is distributed worldwide as free software for all scientists working in educational research non profit institutions Users from commercial or non educational institutions must obtain the au thor s written permission before using the software The scratch files can occupy about 100 MB in some extreme circumstances 10 CHAPTER 1 INTRODUCTION leg J Figure 1 2 Number of Gammas e e eee 1e6 od processed stack entries Lc ee particles as a function of the wab a sd Heavy
227. oint coordinate system 74 199 201 202 207 shower maximum 27 36 78 91 SIBYLL v 3 4 23 25 68 94 120 122 126 216 220 223 226 227 particle codes 94 146 single shower tables 67 80 107 slant atmospheric depth see atmospheric depth slant splstint see AIRES object library spaddnu11 see AIRES object library spaddp0 see AIRES object library spaddpn see AIRES object library special primary particles v 3 5 8 61 70 73 84 88 90 100 115 129 131 133 134 144 163 165 199 211 222 logging 76 speiend see AIRES object library speigetmodname see AIRES object library speigetpars see AIRES object library speimv see AIRES object library 235 speistart see AIRES object library speitask see AIRES object library spinjpoint see AIRES object library splitting algorithm 23 86 217 218 extended see extended Hillas splitting algorithm spnshowers see AIRES object library sprimname see AIRES object library statistical weight factor 29 32 34 35 66 119 135 summary file 8 57 60 77 78 task summary script file 8 57 77 81 82 136 216 220 task definition 45 tasks processes and runs 45 58 103 thinning v 2 4 8 10 27 30 33 38 51 66 85 110 119 135 154 221 AIRES extended algorithm 29 34 35 40 66 221 223 Hillas algorithm 9 28 29 31 34 40 thisairesversion see AIRES object library threshold energies 23 26 52 53 68 70
228. on Atmospheric depth in g cm Returned value Double precision The value of the function at the specified x 186 APPENDIX D THE AIRES OBJECT LIBRARY grandom FORTRAN r grandom C r grandom This function invokes the AIRES random number generator and returns a pseudo random num ber with normal Gaussian distribution zero mean and unit standard deviation It is necessary to initialize the random series calling raninit before using this function Returned value Double precision The Gaussian pseudo random number APPENDIX D idlcheck THE AIRES OBJECT LIBRARY 187 FORTRAN ikey idlcheck dirname C ikey idlcheckc amp dirname Checking a string to see if it matches any of the IDL instructions currently defined that is the ones corresponding to the most recently opened compressed file Arguments dirname Input string Name of the IDL directive to be checked can be abbreviated accord ingly with the rules described in appendix B Returned value Integer If an error occurs then the returned value will be negative Other return values are the following 0 1 10 The string does not match any of the currently valid IDL instructions The string matches a directive belonging to the basic instruction set with no pa rameter s associated with it for example Help The string matches a directive belonging to the basic instruction set If there is a parameter associated with
229. on level corresponds to observing level 0 while the ground level corresponds to observing level nofol 1 For example if the injection ground level is placed at 0 1000 g cm the directive ObservingLevels 19 will set 19 observing levels placed at depths 50 100 150 950 g cm OutputListing Syntax OutputListing Brief Full Default OutputListing is equivalent to OutputListing Brief OutputListing Brief is assumed in case of missing specification d Hidden output data items are not printed in the output summary file unless OutputListing Full is specified PerShowerData Syntax PerShowerData option Default PerShowerData is equivalent to PerShowerData Full PerShowerData Brief is assumed in case of missing specification s Directive to control the amount of individual shower data to be stored after each shower is completed option is a character string that can take any one of the following values None Brief or Full When None is specified no individual shower data is saved The Brief level implies saving global parameters such as the depth of shower maximum Xmax for example and the Full level is the Brief level plus all the single shower tables see page 119 PhotoNuclear Syntax PhotoNuclear On Off Default PhotoNuclear is equivalent to PhotoNuclear On PhotoNuclear On is assumed in case of missing specification s h Switch to include exclude the inelastic collisions gamma air nucleus photonuc
230. ontrol If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means successful return 1 means that an invalid particle coding system was specified by codsys in this case the default coding system is used For nuclei the notation code A 100000 Z is used APPENDIX D THE AIRES OBJECT LIBRARY 147 ciorshutdown FORTRAN call ciorshutdown C ciorshutdown Terminating in an ordered fashion a compressed file analysis session This routine should be invoked at the end of every CIO processing program 148 APPENDIX D THE AIRES OBJECT LIBRARY clockrandom FORTRAN r clockrandom C r clockrandom This function invokes the AIRES elementary random number generator and returns a pseudo random number uniformly distributed in the interval 0 1 generated with the current clock and CPU usage lectures No initialization is needed before using this random number generator WARNING This function is not to be used as a high quality random number generator This routine is intended only
231. opencrofile vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means successful return APPENDIX D THE AIRES OBJECT LIBRARY 181 getlgtrecord FORTRAN okflag getlgtrecord channel currol updown intfields realfields altrec vrb irc C okflag getlgtrecord amp channel amp currol amp updown amp intfields 1 amp realfields 1 amp altrec amp vrb amp irc Reading a record from a compressed longitudinal particle tracking file and returning the read data in a level per level basis This routine invokes getcrorecord to get a record from the corresponding compressed file when it is necessary and must be used jointly with getlgtinit Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile currol Output integer Observing level crossed by the particle updown Output integer Up down indicator 1 if
232. optionally links to two well known external hadronic interaction packages namely SIBYLL 6 and QGSJET 7 2 2 3 Processing the interactions We are going to briefly describe how the different interactions are processed in AIRES We shall focus in the computational aspects of these procedures a more detailed description of the physics involved in such processes is going to be published elsewhere 23 Most of the procedures here described are part of the group of physical algorithms already intro duced and virtually all of them are implemented equivalently as in the simulation program MOCCA 1 First of all it is necessary to express that this description is a general one The actual algorithms do include a number of technical details whose complete explanation is beyond the scope of this work even if their philosophy is concordant with the scheme here presented As mentioned below in AIRES the particles are stored in arrays stacks and processed sequen tially Each particle entry consists of different data items containing the different variables that char acterize it Particle code energy position direction of motion etc For the simulation engine the shower starts when the primary particle is added to the previously empty stack Then the stack processing loop begins Let E r t u be respectively the kinetic energy position time and direction of motion of a given particle identified by its particle code kp When this particle
233. ord was successfully re read False otherwise EOF or T O error APPENDIX D THE AIRES OBJECT LIBRARY 199 spIstint FORTRAN call splstint csys x1 yl z1 irc C splstint amp csys amp x1 amp yl amp z1 amp irc Setting manually the position of the first interaction When using special primary particles processed by external modules which may inject more that a single primary AIRES cannot determine automatically the point where the first interaction takes place and will take it as equal to the injection point unless it is set explicitly using splstint This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments csys Input integer Parameter labeling the coordinate system used csys 0 selects the AIRES coordinate system csys 1 selects the shower axis injection point system de fined in section 3 5 x1 yl z1 Input double precision Coordinates of the first interaction point with respect to the chosen coordinate system in meters irc Output integer Return code 0 means normal return 200 APPENDIX D THE AIRES OBJECT LIBRARY spaddnull FORTRAN call spaddnull pener pwt irc C spaddnull amp pener amp pwt amp irc Adding a null unphysical particle to the list of primaries to be passed from the external module to the main simulation program This particle will not be propagated but its energy will be a
234. ositive it gives the absolute thinning energy in GeV Otherwise it indicates a relative thinning specification being Eth tp Eprimary APPENDIX D THE AIRES OBJECT LIBRARY 155 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 29 30 31 32 33 34 35 36 37 Injection altitude m 3 Injection depth g cm Ground altitude m Ground depth g cm7 Reserved for future use Altitude of first observing level m Vertical depth of first observing level cm Altitude of last observing level m Vertical depth of last observing level g cm Distance between consecutive observing levels in g cm Site latitude deg Site longitude deg Geomagnetic field strength F nT Local geomagnetic inclination I deg Local geomagnetic declination D deg Amplitude of random fluctuation of magnetic field Reserved for future use Minimum lateral distance used for ground particle histograms m Maximum lateral distance used for ground particle histograms m Minimum energy used for histograms GeV Maximum energy used for histograms GeV Reserved for future use Minimum radial distance parameter for the most recently opened compressed file m Maximum radial distance parameter for the most recently opened compressed file m shprimcode Output integer array For i from 1 to intdata 1 shprimcode i gives the corresponding primary particle code The codi
235. ositrons are not followed using detailed calculations when their energy is below the one specified by means of this directive This means that several processes are not taken into account for example Coulomb scattering energy must be greater than or equal to 45 keV This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES ELimsTables Syntax ELimsTables minenergy maxenergy Default ELimsTables 10 MeV emax emax is the maximum between 10 TeV and 0 75 Eprimary s This directive defines the energy interval to use in the energy distribution tables his APPENDIX B IDL REFERENCE MANUAL 119 tograms Each energy distribution histogram consists of 40 logarithmic bins starting with minenergy lower energy of bin 1 and ending with maxenergy upper energy of bin 40 EMtoHadronWF Ratio End Exit Syntax EMtoHadronWFRatio ratio Default EMtoHadronWFRatio 88 s h Ratio between the electromagnetic and hadronic thinning weight factors This instruction permits setting the ratio Agm of equation 2 23 ratio must be equal or greater than 1 The default value of 88 adjusted taking into account the results of representative simulations is normally adequate Syntax End d End of directive stream for the current input file The file is no more scanned when this directive is found If End is not present the file is entirely scanned Syntax Exit Ix d
236. outine In general all the FORTRAN routines of the library can be directly called from a C program In a few cases it was necessary to write special C routines which were named appending a c to the original FORTRAN name as in the case of opencrofile that must be called opencrofilec from a C program see page 196 144 APPENDIX D THE AIRES OBJECT LIBRARY 145 It is also worthwhile mentioning that some FORTRAN compilers do place an underscore _ after the names of the routines In such cases this character must be manually appended to all the routines used within the C program excluding of course all the special C routines of the previous paragraph D 2 List of most frequently used library modules In this appendix we list the definitions of the most frequently used routines alphabetically ordered At each case the FORTRAN as well as the C calling statements are placed cioclose FORTRAN call cioclose C cioclose Closing all the currently already opened CIO files cioclosel FORTRAN call cioclosel channel C cioclosel1 amp channel Closing an already opened CIO file Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile 146 ciorinit APPENDIX D THE AIRES OBJECT LIBRARY FORTRAN call ciorinit inilevel codsys vrb irc C ciorinit amp inilevel amp codsys am
237. p vrb amp irc Initializing the AIRES compressed I O system for reading data This routine must be invoked at the beginning of every program using the compressed I O system routines Arguments inilevel Input integer Initialization switch If inilevel is zero or negative all needed initial ization routines are called If positive only the CIO system is initialized The other rou tines must be called within the invoking program before calling ciorinit inilevel 1 means complete cio initialization while inilevel gt 1 implies only particle coding initial ization This last case allows changing the particle coding system at any moment during a CIO processing session codsys Input integer Particle coding system identification This variable permits selecting among several particle coding systems supported by AIRES see table 4 7 The menu of available systems is the following 0 1 O oo ou A AIRES internal coding system AIRES internal coding for elementary particles and decimal nuclear notation code A 100 Z Particle Data Group coding system 32 extended with decimal nuclear notation CORSIKA program particle coding system 30 GEANT particle coding system 33 SIBYLL particle coding system 6 extended with decimal nuclear notation MOCCA style particle coding system extended with decimal nuclear notation Any other value is equivalent to codsys 1 vrb Input integer Verbosity c
238. particles crossing the different levels Only the range bodata0 eodata0 is used weights Input double precision array eodata0 Positive weights to be assigned to each one of the data points Only the range bodata0 eodata0 is used ws Input integer If ws 2 the weights are evaluated internally proportionally to the square root of the number of particles If ws 1 they must be provided as input data If ws 2 the array weights is not used minnmax Input double precision Threshold value for the maximum number of particles in the input data set The fit is not performed if the maximum number of particles is below this parameter If minnmax is negative it is taken as zero nminratio Input double precision Positive parameter used to determine the end of the data set Must be equal or greater than 5 Once the maximum of the data set is found the points located after this maximum up to the point where the number of charged particles is less than the maximum divided nminratio The remaining part of the data is not taken into account in the fit A similar analysis is performed with the points located before the maximum The recommended value is 100 A very large value will enforce inclusion of all the data set APPENDIX D THE AIRES OBJECT LIBRARY 171 bodataeff eodataeff Output integer The actual range of data points used in the fit nmax Output double precision Estimated number of charged particles at the shower max im
239. pe of this section and will be published elsewhere 27 Using a realistic magnetic field of strength 25 uT the deflections are less evident but not negli gible as illustrated in figure 2 20 The comments here presented are not intended to be a complete analysis of the influence of the CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 41 E Ej 1000 100 0 y 0 1000 100 A E Ej 1000 E lt o e 1000 2 2 5 3 3 5 log r m E E 1000 100 0 u 0 1000 100 3 3 5 log r m Figure 2 18 Lateral distributions of muons electrons and gammas represented as 2D false color plots left column and contour curves plots right column The positive x axis is directed towards the arrival direction The data corresponds to a single 3 x 101 eV proton shower with a zenith angle of 70 degrees The environmental parameters correspond to the El Nihuil site located in Argentina see table 3 2 and the simulations were done with a 10 thinning level and Wy 20 42 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 1500 1500 a 1000 10 1000 500 500 0 0 500 1 500 1000 1000 1500 a 1500 10 1000 0 1000 1000 0 1000 E 1500 1500 fag gt 1000 10 1000 500 500 0 0 500 1 500 1000 1000 1500 1 1500 10 1000 0 1000 1000 0 1000 X m X m Figure 2 19 Lateral distributions of positive and negative muons represented as 2D false color plots The upper graphs correspond
240. pletely simulated Considering for instance a hard simulation regime where 2 x 101 eV primary energy showers proton or iron are simulated with 1077 relative thinning level using the standard Hillas algorithm see section 2 3 generate a compressed ground particle file of size less than 11 MB shower when storing all the particles whose distance from the shower core is larger than 50 m and less than 12 km The green unit named special primaries consists basically in a kernel operated interface with user provided external modules capable of generating lists of particles that will be used to initiate a shower This feature allows the user to start showers initiated by non conventional exotic primary particles like neutrinos for example The math and physical data routines are called from several units within the program and provide many utility calculations In particular they contain the atmospheric model used to account for the varying density of the Earth s atmosphere and the geomagnetic field auxiliary routines that can CHAPTER 1 INTRODUCTION 9 evaluate the geomagnetic field in any place around the world 1 2 Computer requirements The computer requirements to simulate air showers largely depend upon the characteristics of each particular task In particular CPU time requirements can be very hard specially when the simulations are done using low thinning energies For example Ethinning lt 10 7 Eprimary Using the H
241. precision Particle weight Must be equal or greater than one irc Output integer Return code can be one of the following 0 The particle was successfully added 8 Negative kinetic energy 9 Particle weight less than 1 10 The direction of motion is a null vector 11 Invalid coordinate system specification 202 APPENDIX D THE AIRES OBJECT LIBRARY spaddpn FORTRAN call spaddpn n pcode pener csys ldu uxyz pwt irc C spaddpn amp n amp pcode amp pener amp csys amp ldu amp uxyz 1 1 amp pwt amp irc Adding a set of n primary particles to the list of primaries to be passed from the external module to the main simulation program This routine should be used only within modules designed to process special primaries and following the guidelines of section 3 5 page 70 Arguments n Input integer The number of particles to add to the list pcode Input integer array n Particle codes accordingly with the AIRES coding system described in section 2 2 1 page 20 pener Input double precision array n Kinetic energies GeV csys Input integer Parameter labeling the coordinate system used csys 0 selects the AIRES coordinate system csys 1 selects the shower axis injection point system de fined in section 3 5 ldu Input integer Leading dimension of array uxyz must be equal or greater than 3 uxyz Input double precision array Idu n Directions of motion with respect to the
242. production algorithm appearing for low energy muons with very small probability e Changed some incorrect error messages appearing when opening inexistent compressed files e Fixed several minor technical problems not affecting the results of the simulations e Fixed a series of minor bugs in the ARS e Detected and fixed some problems in the installation procedure for SGI systems 215 216 APPENDIX E RELEASE NOTES Algorithm modifications New hadronic models SIBYLL 2 1 6 and QGSJETO1 7 Nuclear interactions The nucleus nucleus cross sections as well as the nucleus nucleus collisions are now processed via the external hadronic models Propagated nuclei The propagation algorithms can now process nuclei beyond iron with Z up to 36 Other Updated value of Avogadro s constant 6 02214199 x 1073 according to 34 Input Directive Language The number in brackets placed after directive names indicate the page where the corresponding di rective is described New directives e ExtNucNucMFP 120 e MinExtNucCollEnergy 126 e TSSFile 136 Directives related to parameters which changed their default values or parameter ranges e ThinningWFactor 135 e MinExtCollEnergy 126 Output data TSS file The task summary script file is a new output file that includes general information about the input parameters of a simulation and some global observables in the format Keyword value suitable for processing wi
243. pstring is a string of characters to set available options s h suppress include file header x X include border bins as comments within the data U do not include border bins r d normal density lateral distributions L 1 distributions normalized as d d logo d d1n r a express atmospheric depth as vertical slant depths K M G T P E express energies in keV MeV EeV The default options are hxrG ExtCollModel Syntax ExtCollModel On Off Default ExtCollModel is equivalent to ExtCol1lModel On ExtCollModel On is assumed in case of missing specification s Switch to enable disable the external hadronic interactions model SIBYLL 6 in the case of the Aires program or QGSJET 7 for the AiresQ main simulation program This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES ExtNucNucMFP Syntax ExtNucNucMFP On Off Default ExtNucNucMFP is equivalent to ExtNucNucMFP On ExtNucNucMFP On is assumed in case of missing specification s h Switch to enable disable calculation of mean free paths for nucleus nucleus collisions via the external hadronic interactions model SIBYLL 6 in the case of the Aires program or QGSJET 7 for the AiresQ main simulation program If the switch is set to Off then the nucleus nucleus mean free paths are evaluated using an AIRES built in procedure In this case the mean free paths ar
244. pt file file extension tss is a text file containing information about the main input and output parameters of the simulation in a format suitable for further processing by other programs The format of this file is very simple Each data item is written using a single line in the format Keyword value Some comments are included to make the file more human readable The comment lines begin with a comment character or the character set with the CommentCharacter directive In figure 4 1 a typical TSS file is displayed Some of the records were not displayed for brevity The first data items correspond to the version of AIRES used for the simulations and the units cor responding to different quantities written in the file The general data basic and additional input parameters and miscellaneous sections contain the current values of all the input parameters The last section contains a summary of shower observables Using one line per shower a series of shower output data is displayed The ShowerPerShowerKey line gives the key with the meaning of each one of the columns of the shower data lines starting with the primary code key PrCode for the first item after the equal sign and continuing until completing all the following items 1 PrCode Primary particle code 2 PrEgy Primary energy 3 Zenith Shower zenith angle 4 Azim Shower azimuth angle 5 Xiv Vertical depth of first interaction 6 Xmaxv Vertical depth of shower maximum 7
245. put parameter gt The simulation program communicates with the script via a file that contain information about the status of the simu lations Use p AiresS to explicitly specify the simulation program linked to the SIBYLL hadronic collision model CHAPTER 5 THE AIRES RUNNER SYSTEM 103 5 2 1 Canceling tasks and or stopping the simulations Every spooled task can be canceled by means of the command airesuntask for example airesuntask my other_file will erase the second spooled task of the preceding section If the airesuntask command is invoked with no parameters then it will prompt the user to cancel each one of the spooled tasks It is not recommendable to remove the spool entries corresponding to tasks that are currently running In such cases it is better to first stop the simulation program and wait until the AIRES Runner System shuts down The simulation program can be stopped with the ARS command airesstop which generally is invoked with no arguments This script originates an ordered shutdown of the simulations which includes an update of the internal dump file and may take up to several minutes to effectively interrupt the simulations The command airesstatus can be used to monitor the status of the system during this process On the other hand a currently running simulation can be immediately aborted by means of com mand aireskill In this case the corresponding processes are killed without any previous auto saving oper
246. r one The fields that make the beginning end of shower record are listed in table 4 1 4 2 Tables 4 3 and 4 4 describe the fields of the special primary related records In these and in any other records the data fields can be classified in integer and real fields The fields contained in such delimiting records account for general air shower parameters or observables and were included for special analysis tasks In the case of showers initiated by special primary particles see section 3 5 the Primary parti cle code of the corresponding beginning of shower record will not correspond to a standard particle code Instead the returned code will be a negative integer with an absolute value slightly smaller than 100000 In those cases the beginning of shower record will be followed by a series of external primary particle records one for each injected primary particle This series ends with a special primary trailer record which will precede the default particle records written for that shower The fields included in the default records associated with particle data can be selected at compile time among the various available alternatives The installation configuration file see appendix A contains detailed instructions on how to select the particle record options The most relevant physical properties of the ground particles can be saved in the ground com pressed file namely Particle code An integer
247. r the existence of the file myname idf After finding it the task version will be increased by one producing a IDF named myname_001 idf and then the new task will be executed normally On successive calls the version number will be increased repeatedly until finding the first non existent file with name myname vvv idf Notice however that it is not possible to append new showers to any task that was initialized with a previous version of AIRES 60 CHAPTER 3 STEERING THE SIMULATIONS 3 3 2 File directories used by AIRES The simulation programs read and or write several files that contain different kinds of data By default all the files generated by AIRES are located in the working directory defined as the current directory at the moment of invoking AIRES There are certain cases however where this setting is not adequate For that reason the IDL instruction set contains directives allowing to control the placement of AIRES files Let us first define the set of directories used by the AIRES system during the simulations Global Containing the log IDF ADF and summary files Compressed output Sometimes referred simply as Output directory contains the compressed out put files Export Containing all the exported data files Scratch Containing most of the internal files that are generated during the simulations including the particle stack scratch files The output and scratch directories default to the current working dir
248. rary routine must be placed within the mentioned calls Once the interface is started the system is ready to accept primary particles that will be added to the primary particle list The basic routine to add primaries to the list is spaddp0 For each invocation of this routine the corresponding particle is added to the internal list of particles There is no limit in the number of primary particles that can be included in the mentioned list but the sum of their energies must not be larger than the primary energy specified in the input instructions and stored in the variable primary_energy appearing in figure 3 3 Arguments number 3 to 6 of routine spaddp0 define the direction of motion of the corresponding particle Argument number 3 is an integer switch selecting the coordinate system to use and the remaining quantities give the components of a vector not necessarily normalized pointing in the direction of motion of the particle There are two options for argument number 3 variable csys in the description of page 201 0 To select the AIRES coordinate system defined in section 2 1 1 page 11 CHAPTER 3 STEERING THE SIMULATIONS 73 An example of an external module to process special primary particles program specialprim0 implicit none Declaration of variables retrieved when starting the interface with the calling program integer shower_number double precision primary_energy double precision default_injection_position 3 double
249. re taken into account when designing AIRES output units together with an analysis of the output system of existing programs 1 30 As a result the simulation program was provided with two air shower data output units The particle data unit and the summary unit The particle data unit generates compressed particle data files containing detailed information in a per particle basis of particles reaching ground or passing across the different observing levels The other output unit processes data stored in a number of internal tables or histograms which were calculated during the simulations and which correspond to standard observables like lateral distributions energy distributions and so on The output system will be treated in detail in chapter 4 page 77 Nevertheless it is worthwhile mentioning here that there are several IDL directives that permit controlling its behavior In our example of figure 3 1 page 51 the directives SaveInFile and SaveNotInFile control the kind of particles that are saved in the corresponding compressed files identified by their extensions lgtpcles and grdpcles The default action for the file containing record for the particles reaching ground extension grd peles is that all particle kinds must be saved On the other hand no particles are saved by default in the longitudinal tracking particle file extension Igtpcles Therefore the statements SaveInFile lgtpcles e e SaveNotInFile grdpcles gamma m
250. recision Cosine of the zenith angle O see figure 2 1 corresponding to the integration line Must be in the range 0 1 zground Input double precision z coordinate in meters of the intersection point between the oblique axis and the z axis which is normally coincident with the ground altitude Returned value Double precision The slant atmospheric depth in g cm or zero in case of error or invalid argument Appendix E Release notes This appendix contains a brief summary of the new developments that are included in the current version of AIRES 2 6 0 as well as a description of the differences with the previous release of the system 2 4 0 The number in brackets placed after directive names or library routines indicates the page where the corresponding directive routine is described Example TaskName 135 E 1 Differences between AIRES 2 6 0 and AIRES 2 4 0 Bugs Several problems with AIRES 2 4 0 simulation program were detected or reported by several users All the errors in the program s code mostly minor bugs were fixed and are no longer present in the current version of AIRES Some of those bugs are e Approximate processing of corrections to the arrival times of heavy neutral particles when saving them into the ground particles file The problem does not affect the propagation of the particles The saving algorithm has been improved to overcome this problem e Corrected a minor bug in the muonic pair
251. record The difference between this routine and the mentioned one is that regetcrorecord re scans the last read record instead of advancing across the input file regetcrorecord is thought to be used jointly with getcrorectype crorecfind and other related procedures Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile intfields Output integer array Integer fields of the record For a complete description of this argument see routine getcrorecord realfields Output double precision array Real fields of the record For a complete description of this argument see routine getcrorecord altrec Output logical Alternative default record type label See getcrorecord vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code For a complete description of this argument see routine getcrorecord Returned value Logical True if a rec
252. rent locations For such cases a portable file format is needed and the ADF becomes essential to enable data analysis in non compatible workstations If the ADF was not generated during the simulations or if the simulations were performed using a version of AIRES previous to version 2 0 0 it must be created manually The current AIRES distribution includes an IDF to ADF converting program whose default name is AiresIDF2ADF This program can be used directly It is just necessary to invoke it no arguments needed and answer to the prompts that will be appearing On the other hand the ARS includes a special shell script that permits converting files without calling AiresIDF2ADF manually Let us illustrate how to use this command with an example Sup pose in a certain place there are some IDF files that need to be converted to ADF format The UNIX command idf2adf tasknamel taskname2 taskname3 will search for the files tasknamel1 idf taskname2 idf etc and will call AiresIDF2ADF as many times as necessary to create the portable files tasknamel adf taskname 2 adf etc Of course the old IDF files will remain unchanged 108 CHAPTER 5 THE AIRES RUNNER SYSTEM This script will work well in most cases However there might be special situations where it is necessary to use AiresIDF2ADF manually for example when the IDF file is renamed with a new name not ending with idf Appendix A Installing AIRES and maintaining existing inst
253. rgy particles Prentice Hall New Jersey USA 1956 16 We were not able to find official references related with Linsley s standard atmosphere model References 1 30 contain information about parameterization data 17 A Cillis and S J Sciutto J Phys G 26 309 321 2000 18 A Cillis and S J Sciutto Phys Rev D 64 013010 2001 19 A B Migdal Phys Rev 103 1811 1956 20 A Cillis C A Garcia Canal H Fanchiotti and S J Sciutto Phys Rev D 59 113012 1999 21 D Heck private communication 22 T K Gaisser Cosmic Rays and Particle Physics Cambridge University Press Cambridge 1992 23 S J Sciutto in preparation 24 L D Landau and I Ya Pomeranchuk Dokl Akad Nauk SSSR 92 535 735 1953 25 S Klein preprint hep ph 9820442 1998 26 I Vattulainen T Ala Nissila K Kankaala Phys Rev Lett 73 2513 1994 27 S J Sciutto in preparation 28 V S Berezinskii et al V L Ginzburg editor Astrophysics of cosmic rays North Holland 1990 29 T K Gaisser and A M Hillas Proc 15th ICRC Plovdiv 8 353 1977 30 D Heck J Knapp J N Capdevielle G Schatz and T Thouw Forschungszentrum Karlsruhe Report FZKA 6019 1998 31 P Billoir private communication 32 Particle Data Group C Caso et al The European Physical Journal C3 1 1998 website www pdg 1bl gov 230 REFERENCES 33 CERN Program library Long Write
254. rs to be adjusted Notice that Nen Xo 0 5 and that Nen X is taken as 0 for X lt Xo A weighted nonlinear least squares fit performed with the aid of the very robust Levenberg Mardquardt algorithm as implemented in the public domain software library Netlib 10 is done after the simulation of every individual shower is completed The values reported in the summary file correspond to the plain average of all the fits with reasonable results converged fits The number of such converged fits is also reported Tables section The output data tables listed in appendix C page 137 that are automatically calculated during the simulations can be totally or partially included within the output summary file An index of such tables can also be printed using the directive TableIndex The PrintTables directive must be used to include one or more tables within the output summary file Its syntax is shown in the following example PrintTables 1291 Options RM This instruction orders AIRES to print table 1291 longitudinal development of all charged par ticles into the summary file The options used are R to list RMS errors of the means and M to include maximum and minimum data as numerical entries For a detailed explanation of the directive PrintTables see page 130 4 1 2 Exporting data An interesting feature of both the summary and the main simulation programs is that they are able to generate output files containing an
255. rsions of AIRES Atmosphere Syntax Atmosphere label Default Atmosphere 1 s Switches among different atmospheric models label is an integer labeling the models avail able These models are currently two 1 Linsley s standard atmosphere model 2 Linsley s model for the South Pole Brackets Syntax Brackets On Off Brackets On obcb ec Default Brackets On amp d Controls the behavior of the variable replacement algorithm used while scanning the input file When the feature is disabled Brackets Off the input lines are not scanned to search for defined variables to be replaced When Brackets On is in effect and there are defined variables then variable substitution is performed when it corresponds The active variable names must be APPENDIX B IDL REFERENCE MANUAL 117 enclosed using the current brackets which can be changed using this directive The arguments ob cb and ec correspond respectively to the opening and closing brackets and the bracket escape character These single character variables must be different and can be specified with the same rules that apply for the argument of the CommentCharacter directive CheckOnly Syntax CheckOnly On Of Default CheckOnly is equivalent to CheckOnly On CheckOnly Off is assumed in case of missing specification d When CheckOnly is enabled the simulation program reads and process all the input data normally performs the internal consistency
256. s These optimizations are based on two key concepts i Even if a non vertical shower can start in a very distant point most of the shower development takes place relatively near the z axis where the plane Earth approximation is acceptable ii Many calculations that employ spherical geometry can be substantially simplified if the coordinate system is temporarily rotated so the involved point lies near the new z axis and plane geometry is used in the rotated system If necessary an inverse rotation is applied to express results in the original coordinate system In order to apply the first concept a zone where the Earth can be acceptably approximated as plane must be defined As it will be justified later in this chapter see section 2 1 4 the Earth s spherical shape can be ignored in a conic region region centered at the z axis with a varying diameter ranging from 8 km at sea level to 45 km at an altitude of 100 km a s l The average limits of that region about 22 km diameter are indicated in figure 2 1 To fastly perform the rotation operations needed to express coordinates and vector in a temporary local coordinate system it results convenient to use a redundant set of coordinates defined as follows Let r be the position vector of a point with coordinates x y z We define the vertical altitude zy of the point as the minimum distance between the point and the sea level surface It is straightforward to demonstrate that Re z
257. s may demand up to 12 CPU hours and restarting the simulation program the input file is scanned again and the new settings will become effective The changes experimented by these dynamic pa rameters will be recorded in the log file extension lgf in the following way gt dd Mmm yyyy hh mm ss Reading data from standard input unit gt dd Mmm yyyy hh mm ss Changing maximum number of showers per run From 2 to Infinite gt dd Mmm yyyy hh mm ss Changing maximum cpu time per run From 6 hr to 3 hr The dynamic directives can be changed as many times as needed including the total number of showers controlled by directive TotalShowers which can be modified either during the simulations or after completing them to append new showers to an already finished task It is important to remark that the mechanism of dividing a task in several process is possible be cause all the relevant simulation data is saved into the internal dump file and recovered in successive invocations of AIRES In some applications however it is necessary to completely disable this mechanism and force AIRES to start a new task every time a new new process starts This can be done with the help of the Forcelnit directive like in the following example Task myname ForceInit On the first invocation of AIRES the task myname will be initialized and executed accordingly with the input directives In a second call the AIRES initializing procedures will check fo
258. s 14 555 7 265 The ratio between mean atomic number and weight is 0 499 The US standard atmosphere is sometimes referred as the US extension of the ICAO International Civil Aviation Organization standard atmosphere 14 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES A E Figure 2 2 Mean molecular weight of the atmosphere as a function of the vertical 16 ee ee ee Oe ee altitude US standard 0 1 1 10 100 atmosphere 14 The line is h km only to guide the eye On the other hand the density of the air does change considerably with the vertical altitude as shown in figure 2 3 The dots are the US standard atmosphere data taken from reference 14 The green full line corresponds to Linsley s parameterization of the US standard atmosphere 16 also called Linsley s atmospheric model or Linsley s model which effectively reproduces very accurately the US standard atmosphere data The isothermal atmosphere p h poe RT 2 3 was also plotted dotted red line for comparison pg and T match the corresponding US standard atmosphere values at sea level Figure 2 3 Density of the air as a function of the vertical altitude The dots represent the US standard atmosphere data 14 while the full green line corresponds to Linsley s model 16 and the dashed red one to the isothermal atmosphere on p h po e IMA RL with 0 1 1 10 100 po 1 225 kg m h km M 28 966 and T 288 K 1 00 le 3 D
259. s Re 6370949 m centered at the Earth s center The ground level and the injection level refer to spherical surfaces concentric to the sea level surface and intersecting the z axis at z zg zg gt 0 and z z zi gt zg respectively The shower axis of a shower with zenith angle O is defined as the straight line that passes by the intersection point between the ground level and the z axis and makes an angle with the z axis 0 lt lt 90 The azimuth angle is the angle between the horizontal projection of the shower axis and the x axis 0 lt lt 360 In AIRES version 1 2 0 all the spherical surfaces mentioned in the preceding paragraphs were approximated as planes This approximation is justified every time the horizontal distances involved are negligible in comparison with the Earth s radius Re This is the case for showers whose zenith angle is small but certainly not for those with large zenith angles especially for quasi horizontal showers For AIRES version 1 4 0 or later the curvature of the Earth is taken into account to make it possi ble to reliably simulate showers with zenith angles in the full range 0 lt lt 90 Since full spherical 11 12 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES Limits of plane Earth zone k 22 km Pad ok Figure 2 1 AIRES coordinate system calculations are computationally expensive an effort was made to optimize the corresponding algo rithm
260. s from the data available at much lower energies and there is still no definitive agreement about what is the most convenient model to accept among the several available ones The AIRES system is a set of programs to simulate such air showers One of the basic objectives considered during the development of the software is that of designing the program modularly in order to make it easier to switch among the different models that are available without having to get attached to a particular one Several simulation programs that were developed in the past were studied in detail in order to gain experience and improve the new design Among such programs the well known MOCCA AIRES is an acronym for AIR shower Extended Simulations 2 CHAPTER 1 INTRODUCTION code created by A M Hillas 1 occupies an outstanding position It has been successfully used to interpret data coming from various air shower experiments can be operated in a wide range of primary energies from 101 eV to 10 eV and permits to perform simulations with a relatively moderate consumption of computer resources The MOCCA program has been extensively used as the primary reference when developing the first version of AIRES 2 released in May 1997 The physical algorithms of AIRES 1 2 0 are virtually equivalent to the corresponding ones from MOCCA 3 The structure of AIRES is designed to take advantage of present day computers and therefore the new program represents an
261. s not taken into account in the original selection The result of the corrective action is that of canceling some interactions In such cases the particle is left unchanged and remains in the stack for further processing Particles arriving to destination The mechanism so far described is capable of generating and propagating all the secondaries that come after the first interaction of the primary particle To let the shower finish it is necessary to determine when a particle should no more be tracked In AIRES this corresponds to the case when one or more of the following conditions hold e The particle s energy is below a given threshold low energy particles e The particle s position is out of the interesting region lost particles e The particle reached the ground level It is very simple to show that this is enough to ensure that the simulation of a shower will end in a finite time Particle monitoring The simulation programs include several monitoring routines that constantly check the status of the particles being propagated and accumulate data then used to evaluate the different air shower observ ables The events that are monitored are e Particles that reach ground level e Particles that pass across predetermined observing levels The observing levels are constant depth surfaces generally located between the injection and ground levels and separated by a constant depth increment AX If No is the number of obser
262. se of positive answer the simulation program will be started with the corresponding input and will be repeatedly invoked if necessary until the task is completed gt All those operations are completely automatic no further user intervention is normally required If there are more than one task to be processed they can be spooled at any moment after launching the first simulations The command airestask my _other_file will make a new spool entry which will be queued after the first one Execution of this task will start as soon as the previous one is finished There is no limit in the number of tasks that can be queued in the ARS spools At any moment during the simulations it is possible to inspect the evolution of the spooled tasks by means of the ARS command airesstatus In the preceding examples the default simulation program which normally is the Aires program will be used There are two alternatives to override the default specification i Modify the default program setting of the initialization file airesrc ii Use the p qualifier of the airestask command airestask p AiresQ yet_another file AiresQ is the name of a variable defined within the initialization file which indicates the executable program that contains a link to the QGSJET hadronic package airestask first assumes a default extension inp for the input file name and as a second alternative tries to find the file whose complete name is as specified in the in
263. similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means successful return 1 means successful return but the dump file was not created using the same AIRES version 8 means that no dump file in the sequence taskname taskname adf taskname idf exists 12 means invalid file name Other return codes come from the adf or idf read routines APPENDIX D THE AIRES OBJECT LIBRARY 189 nuclcode FORTRAN ncode nuclcode z n irc C ncode nuclcode amp z amp n amp irc This routine returns the AIRES code of a nucleus of Z protons and N neutrons as defined in page 20 Arguments z Input integer The number of protons in the nucleus n Input integer The number of neutrons in the nucleus irc Output integer Return code 0 means that a valid pair of input parameters Z N was successfully processed 3 means that the nucleus cannot be specified with the AIRES system 5 means that either Z or N are out of allowed ranges Returned value Integer The nucleus code of equation 2 17 190 APPENDIX D THE AIRES OBJECT LIBRARY nucldecode FORTRAN call nucldecode ncode z n a C nucldecode amp ncode amp z amp n amp a This routine returns the charge neutron and mass numbers corresponding to a given AIRES nuclear code see page 20 Arguments ncode Input integer The AIRES nuclear code of equation 2 17 z Output i
264. sitive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place 184 ghfin APPENDIX D THE AIRES OBJECT LIBRARY FORTRAN x C x ghfin np prepost ghfin amp np amp prepost Numerical evaluation of the inverse of the Gaisser Hillas function equation 4 1 for a given number of particles np The four parameters Nmax Xmax Xo and must be specified previ ously by means of ghfpars Arguments np Input double precision The number of particles If np lt 0 or np gt Nmax the result is a large negative number prepost Input integer Integer parameter labeling which of the two abscissas X has to be returned If prepost is less or equal to 0 then X lt Xmax otherwise X gt Xmax Notice that the inverse of the Gaisser Hillas function is bi valuated Returned value Double precision The value of the inverse Gaisser Hillas function ex pressed in g cm that is x such that np ghfx x APPENDIX D THE AIRES OBJECT LIBRARY 185 ghfx FORTRAN np C np ghfx x ghfx amp x Evaluating the Gaisser Hillas function equation 4 1 for a given depth x The four parameters Nmax Xmax Xo and must be specified previously by means of ghfpars Arguments x Input double precisi
265. ssed by means of the cd commands of the example where directory1 directory2 and directory3 must be different directory specifications Notice also that the third spooling command makes use of an alternative simulation program in order to perform a different kind of simulation Alternative programs may also be necessary when running simulations on clusters sharing the same file system but made with non compatible platforms In those cases it is necessary to have different executable modules for each platform Once such modules are available it is possible to change the default programs corresponding to the different spools by means of suitable modifications to the airesrc initialization The details about how to make the AIRES Runner System work in complex operating environ ments are rather technical and go beyond the scope of this manual Such a job requires normally a good degree of expertise on UNIX systems 5 4 Some commands to manage dump file data Chapter 4 page 77 explains in detail the operations needed to retrieve data stored within the internal dump file in either its binary or ASCII versions Some of them are frequently used and generally involve very similar sequences of instructions A typical example is to export one or more tables corresponding to an already finished task The ARS includes a shell script that can be helpful in those cases Consider for example the command under UNIX airesexport mytask 1001 1205 to 1213 CHAP
266. stributions Frequency distributions recording the number of particles reaching ground as a function of their distance to the shower core Energy distributions Energy spectra of the different particles at ground level Arrival time distributions Mean ground level arrival time of different particle kinds as a function of their distance to the shower core All the output coming from the monitoring routines is saved in the form of data tables that can be easily retrieved by the user see chapter 4 2 2 4 Random number generator AIRES contains many procedures that require using random numbers the most important example being the propagating procedures that were described in the preceding paragraphs Those numbers are adequately generated by means of a built in pseudorandom number generator 1 whose source code is included within the AIRES distribution During the early steps of AIRES development the random number generator was checked with a series of tests including uniformity and correlation tests among others In particular this pseudo random number generator passed the very stringent random walk and block tests described in reference 26 A more detailed description of the different routines associated with the generation of random numbers can be found in appendix D page 144 2 3 Statistical sampling of particles The thinning algorithm The number of particles that are produced in an air shower grows significantly w
267. t Logical output unit s selection flag See routine croheaderinfo vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only error messages will be printed vrb gt 3 is similar to vrb 3 but with the additional action of stopping the program if a fatal error takes place irc Output integer Return code 0 means successful return APPENDIX D THE AIRES OBJECT LIBRARY 151 crofileversion FORTRAN ivers crofileversion channel C ivers crofileversion amp channel Returning the AIRES version used to write an already opened compressed file Arguments channel Input integer Variable that uniquely identifies the I O channel assigned to the corresponding file This variable must be already set by means of routine opencrofile Returned value Integer The corresponding version in integer format for example the num ber 01040200 for version 1 4 2 01040201 for version 1 4 2a etc If the file is not opened or if there is an error then the return value is negative 152 APPENDIX D THE AIRES OBJECT LIBRARY crogotorec FORTRAN okflag crogotorec channel recnumber vrb irc C okflag crogotorec amp channel amp recnumber amp vr
268. t interaction at the original injection point regardless whether that points corresponds or not to an actual point of interaction As an alternative to the default action it is possible to set manually the coordinates of the point of first interaction using routine spIstint page 199 Of course this affects only the statistical analysis of the first interaction depth and has no effect on the propagation of the particles Version of external module The user can assign a version number to the external module This version number must be passed to the main program by means of routine speimv page 206 The version number is stored with all the information associated with the current shower in particular in the compressed output files It is strongly recommended to assign version numbers to external modules that will be used in production simulations We recall here that all the calls to every one of the routines listed in the previous paragraphs must be placed after the call to speistart and before the call to speiend The IDL directive SpecialParticLog allows to print information about the primary particles that are injected after each invocation of the external module Notice that the default is to print no infor mation in the log extension lgf file Chapter 4 Managing AIRES output data 4 1 Using the summary program AiresSry Every time a task is completed the simulation programs invoke some output procedures that create a summary file
269. th other programs For details see section 4 1 3 page 81 AIRES Runner System The ARS includes now support for a BeforeProcess macro For details see section 5 2 2 page 103 NOTE on the QGSJET VERSION The new version of QGSJET requires a long series of initialization calculations requiring several hours of CPU time All the data produced during the initialization phase are saved into two files named QGSDAT01 and SECTNU and can be recovered from them in other invocations of the package It is therefore recommended to keep such files and reuse them in other simulations to avoid long delays due to QGSJET initialization APPENDIX E RELEASE NOTES 217 E 2 Differences between AIRES 2 4 0 and AIRES 2 2 1 Bugs A number of problems with AIRES 2 2 1 simulation program were detected or reported by several users All the errors in the program s code mostly minor bugs were fixed and are no longer present in the current version of AIRES Some of those bugs are e Incorrect processing of a fraction of low energy neutrons Was fixed e Slight modification in et e annihilation and et e bremsstrahlung processes to properly man age the case of very low primary energies e Injected special primaries are now checked to verify that the injection point is above the ground level e Minor bug in xslant library function related to zy initialization Was fixed e Extended the compressed file management routines to support negative ASCII chara
270. th rarely changing parameters directives are respectively marked as d s h Names in typewriter or boldface font refer to keywords while names in ital ics refer to variable parameters Underlined parts of keywords refers to shortest abbreviations Not underlined characters are optional Expressions between square brackets expression are optional while alternatives are written in the following way alt_1 alt2 To specify angles lengths times energies atmospheric depths magnetic fields etc it is required to give two fields separated by blank space number unit number is a decimal number and unit is a character string representing the physical unit used in the specification All the valid units are listed in table 3 1 page 49 Additionally time specifications may be of the form number hr number min number sec where number represents a floating point number Hidden directives are connected to parameters that seldom need to be modified They are not printed in the input data summary unless were explicitly set or a full listing mode was enabled Notice that this only affects output data printing All other directive properties remain unchanged 114 APPENDIX B IDL REFERENCE MANUAL 115 B 1 List of IDL directives Comment character For every scanned input line all characters placed after the comment character are ignored Syntax amp label IDL label Labels are used by directives Remark and Sk
271. than one observing level during its life it is clear that the longitudinal files can potentially be much larger than the average ground particle files For that reason a special effort was made to save as much space as possible and various record formats were defined to allow the user to select just the necessary fields The record format selection can be done during installation following the instructions placed in appendix A page 109 Table 4 6 page 91 lists all the defined data fields for the different default records The second integer field named Observing levels crossed contains information about the ob serving levels the particle has crossed and simultaneously about its direction of motion Let No No lt 510 be the number of defined observing levels At a certain monitoring operation a given particle crosses several observing levels from level p to level i t may be equal to 7 Let uz be the z component of the particle s direction of motion If u gt 0 uz lt 0 the particle goes upwards downwards and therefore if gt t af lt t All this information is encoded in a single integer number called the crossed observing levels key L defined by the following equation L is 512i 512 sua 4 6 where _ J 1 ifu gt 0 a 0 ifu lt 0 OD 92 CHAPTER 4 MANAGING AIRES OUTPUT DATA The three variables that appear in the right hand side of equation 4 6 can be easily reconstructed when L is known see
272. the Hillas algorithm case no weight limits Considering the the distributions of weights for gammas as a typical case it is evident that there is a small fraction of particles having weights up to three orders of magnitude larger than the most probable ones This rare cases are generally the cause of many inconvenients that arise when analyzing the data The plots for finite Wy show clearly that the distributions present a sharp end corresponding to the value of W In the case Wy 1 the gamma distribution ends approximately at the maximum of the nl case curve as expected from CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 33 1000 J 100 H 1000 p 100 F 10 k H oath o h Density Particles m2 OS p rem s Density Particles m2 0 1 50 100 1000 50 100 1000 R m R m 1000 1000 E E e 100 p 100 5 5 amp 10 amp 10 J 2 D z 1 KN J z 1 KS 4 A Ks A d 0 1 L L fi fi 1 Sy 0 1 L L fi L fi a 50 100 1000 50 100 1000 R m R m Figure 2 9 Effect of the thinning energy on the fluctuations of the lateral distribution of muons in the same conditions as in figure 2 7 equation 2 23 where the factor Ag is tuned to give W near the distribution s maximum when Wy is equal to 1 The muon weights are generally smaller than the electromagnetic counterparts see the discus sion of figure 2 9 in page
273. the lower and upper bounds for the 40 bin energy distributions and the respective underflow and overflow bins With the current version of AIRES it is possible to save the tables in a shower per shower basis besides the traditional average tables that have been always available Since this may generate large IDF or ADF files in certain cases the mechanism of individual shower table saving is disabled by default The directive PerShowerData Full must be used to ensure that the individual shower tables are being saved 3 3 7 Random number generator The AIRES random number generator must be initialized before starting any set of simulations The default action is to use a internally generated seed generated with an elementary random number generator that uses the current clock and CPU usage registers Therefore different invocations of AIRES with the same input directives will generally originate different output data because of differ ent initializations of the random number generator The default behavior can be changed if needed The directive RandomSeed allows the user to set the random seed to a given number or to get the seed from an already initialized task These features are illustrated in the following examples 1 The directive RandomSeed 0 1298004637 sets the random seed to a fixed constant The number must be greater than zero and less than one 68 CHAPTER 3 STEERING THE SIMULATIONS 2 The directive
274. the particle is going upwards 1 other wise intfields Output integer array Integer fields of the last read record This includes the non scaled integer quantities and in the last positions the date time specification s if any The calling program must provide enough space for this array The minimum di mension is the maximum number of fields that can appear in a record plus 1 Positions beyond the last integer fields are used as scratch working space The meaning of each data item within this array varies with the class of file processed and with the record type see also argument ire and routine crofileinfo realfields Output double precision array Real fields of the record The calling program must provide enough space for this array The meaning of each data item within this array varies with the class of file processed and with the record type see also argument ire and routine crofileinfo altrec Output logical True if the corresponding record type is positive alternative record type False if the record type is zero default record type vrb Input integer Verbosity control If vrb is zero or negative then no error or informative messages are printed error conditions are communicated to the calling program via the return code If vrb is positive error messages will be printed vrb 1 means that messages will be printed even with successful operations vrb 2 3 means that only 182 APPENDIX D THE AIRES OBJ
275. the simulation program used in the last run This powerful ARS option makes it possible for the user to perform operations of almost every kind after ending the processes Of course a certain degree of expertise with UNIX systems may be required in certain cases Typical examples of operations that can be done using this facility are File movement after completion of tasks for example to massive storage systems alerts of any type about conditions of the system like full disks etc On return the AfterProcess script can communicate with the ARS via the exit code If it is zero then processing will continue normally otherwise the ARS will send a mail notifying the abnormal return code and then will stop If it is necessary to restart the simulations it can be done using the ARS command aireslaunch The following shell script is a very simple example of an after process macro bin sh if 3 EndOfTask then This code will be executed only after ending a task mv 2 grdpcles mysafeplace Ti exit 0 Notice that no action will be taken up to the end of a task Whenever this happens the corresponding ground particle file is moved to another directory The command exit 0 ensures normal return code exit n with n 0 means an abnormal exit and in this case the simulations will be stopped Similarly as in the case of the AfterProcess macro the ARS system will search for a BeforePro cess macro right before in
276. this case the IGRF model is used to evaluate the magnetic field Fluctuations are supported as well QGSJET interaction model included Some approximations had to be done however Kaons and other mesons not treated by AIRES are treated as pions The nuclear fragmentation algo rithm of QGSJET is not used Improved method to evaluate Xmax and Nmax Now a four parameter fit is used AIRES version 1 2 0 30 Apr 1997 This version of AIRES consists of about 200 routines adding up to more than 45 000 lines of source code APPENDIX F AIRES HISTORY 227 The first public version of AIRES package includes many features of the well known program MOCCA for air shower simulation SIBYLL 1 5 external collision package is included Other char acteristics are Energy longitudinal development compressed particle files brief documentation etc References 1 A M Hillas Nucl Phys B Proc Suppl 52B 29 1997 A M Hillas Proc 19th ICRC La Jolla 1 155 1985 2 S J Sciutto AIRES A minimum document Auger technical note GAP 97 029 1997 3 M T Dova and S J Sciutto Air Shower Simulations Comparison Between AIRES and MOCCA Auger technical note GAP 97 053 1997 4 A M Hillas Proc of the Paris Workshop on Cascade simulations J Linsley and A M Hillas eds p 39 1981 5 M Kobal A Filip i and D Zavrtanik Auger technical notes GAP 98 001 and GAP 98 058 1998 6 R Engel T K Gaiss
277. tions of the simulations are as described in figure 2 13 38 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 1e 06 1e 05 1e 04 A z 1e 03 2 1e 02 D v e le 01 a a le 00 Figure 2 15 Lateral le 01 distribution of different kinds of particles reaching ground le 02 The data corresponds to a i single 10 eV vertical proton 100 1000 shower simulated with 10 8 Distance to the core m relative thinning Notice also the behavior of the muon energy which is negligible when the shower starts but grows constantly over passing the pion energy fraction near the ground level Another observables normally used to describe the air showers are the lateral distributions of ground particles that is the number of particles as a function of their distance to the shower axis In figure 2 15 the lateral distribution of various particle kinds are plotted considering distances to the core ranging between 50 and 2000 meters The results correspond to a single shower simulated with 10 8 relative thinning This very low thinning level is responsible for the noticeable smoothness of the distributions maintained even at large distances from the core The basic characteristics of the air shower lateral distributions can be seen from this plot The electromagnetic component that is gammas electrons and positrons is the most important in number and at the same time spreads widely around the core that is the point of maximum particle
278. tives are scanned until either an End directive or an end of file is found Most directives can be placed in any order within the input stream IDL directives can be classified as dynamic or static Dynamic directives are processed every time the input data is scanned Static ones can be set only at the beginning of a task Any subsequent setting will not be taken into account For instance the maximum CPU time per run is controlled by a dynamic directive it can be changed at the beginning of every process and is a parameter that does not affect the results of the simulation the ground altitude instead is an example of a static parameter that cannot be changed during the simulations The IDL sentence begins with the directive name IDL is a case sensitive language and in general directive names mix capital and lowercase letters The directives can be abbreviated Consider for example the following directive name PrimaryParticle You must specify the underlined part and may or may not use the remaining characters Primary PrimaryPart PrimaryParticle refer to the same instruction 3 2 1 A first example There are four directives that should be always specified before starting a simulation task namely the ones that control the task name the statements that provide the primary particle type and energy specifications and the directive which sets the total number of showers to be simulated Such a minimal set of specifications can be express
279. to complete and in such cases the user risks loosing all the simulation run if the system goes down before the task is finished To avoid this inconvenient situation the AIRES simulation system provides a special auto saving mechanism that permits splitting the simulation job into small runs In case of abnormal interruption the simulations can be restarted at the point they were when the last auto saving was performed As explained in chapter 3 page 45 a simulation task may require several invocations of the simulation program if the auto save mechanism is enabled If this is done manually the user must control the sequence of instructions needed to complete the simulations To ease the management of such sequential series of processes a set of scripts were developed with the capability of automatically launching the corresponding jobs These scripts are part of the AIRES Runner System ARS designed as a set of interactive procedures to manage complex simulations tasks The AIRES Runner System works only on UNIX platforms and provides tools for input file checking sequential and concurrent task processing event logging etc This chapter is devoted to present some examples that will help the user to get familiar with the Runner System There are many parameters that modify the behavior of the AIRES Runner System Most of them are user settable and their definition statements are placed within the ARS initializing file airesre In standard AI
280. tory is set by default d Modifying the directory search path for the files included with the Input directive and or executable modules referred by AddSpecialParticle instructions This directive can be used multiple times if required Different search directories can be specified in a single invocation separating them with colons with no embedded blanks The keyword Append indicates APPENDIX B IDL REFERENCE MANUAL 125 that the specified directory ies must be appended to the ones already inserted If InputPath is invoked with no arguments then the search path is cleared LaTeX Syntax LaTex On Off Default LaTeX is equivalent to LaTeX On LaTeX Off is assumed in case of missing specification d If LaTeX On is specified then the output summary file is written using the TEX word processor format Otherwise it is written as a plain text file When this option is enabled a TEX file taskname tex is created simultaneously with the summary file LPMEffect Syntax LPMEffect On Off Default LPMEffect is equivalent to LPMEffect On LPMEffect On is assumed in case of missing specification s h Switch to include exclude the Landau Pomeranchuk Migdal effect 24 19 from the elec tron positron and gamma propagating algorithms The effect is enabled by default Disabling it may lead to non realistic air shower simulations If LPMEffect Off is in effect then the dielectric suppression is also disabled see page 118 Th
281. tring Name of the IDL directive associated with the parameter can be abbreviated accordingly with the rules described in appendix B Returned value integer The current setting for the corresponding parameter In case of error the returned value is undefined APPENDIX D THE AIRES OBJECT LIBRARY 177 getinpreal FORTRAN value getinpreal dirname C value getinprealc amp dirname Getting the current value for a real static input parameter corresponding to the most recently opened compressed file This routine is used to get from the current file s header those real input parameters not returned by routine croinputdata0 see page 154 Arguments dirname Input string Name of the IDL directive associated with the parameter can be abbreviated accordingly with the rules described in appendix B Returned value double precision The current setting for the corresponding parameter In case of error the returned value is undefined 178 APPENDIX D THE AIRES OBJECT LIBRARY getinpstring FORTRAN call getinpstring dirname value slen C getinpstringc amp dirname amp value amp slen Getting the current value for an input static character string corresponding to the most re cently opened compressed file Arguments dirname Input string Name of the IDL directive associated with the parameter can be abbreviated accordingly with the rules described in appendix B value Output string The current param
282. tudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Longitudinal development Energy of gamma rays Energy of electrons Energy of positrons Energy of muons Energy of muons Energy of pions Energy of pions Energy of kaons Energy of kaons Energy of neutrons Energy of protons Energy of antiprotons Energy of nuclei Energy of other charged particles Energy of other neutral particles Energy of e and e Energy of mu and mu Energy of pi and pi Energy of K and K Energy of all charged particles Energy of all neutral particles Energy of all particles APPENDIX C OUTPUT DATA TABLE INDEX 67 68 69 70 71 72 73 74 75 76 77 78 79 80 8l 82 83 84 85 86 87 88 89 90 9 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 Code 2001 2005 2006 2007 2008 2011 2012 2013 2014 2021 2022 2023 2041 2091 2092 2205 2207 2211 2213 2291 2292 2293 2301 2305 2306 2307 2308 2311 2312 2313 2314 2321 2322 2323 2341 2391 2392 2405 2407 2411 2413 Table name Lateral distribution Lateral distributio
283. tween processes 5 3 Concurrent TASKS s 2 S se dca acd O ha ea oe a ld ee oN 5 4 Some commands to manage dumpfiledata 5 4 1 Converting IDF binary files to ADF portable format Installing AIRES and maintaining existing installations A 1 Installing AIRES 2 6 0 in c 8464854484068 445884 A 1 1 Installation procedure step by step A 2 Recompiling the simulation programs CONTENTS CONTENTS ix B IDL reference manual 114 B 1 ListofIDL directives 0 0 00 0 000000 eee ee ee 115 C Output data table index 137 D The AIRES object library 144 D1 G intertace enea ees Side Ee re ho oe Se ce Sede a Se eS 144 D 2 List of most frequently used library modules 0 145 E Release notes 215 E 1 Differences between AIRES 2 6 0 and AIRES 2 4 00 215 E 2 Differences between AIRES 2 4 0 and AIRES 2 2 1 217 F AIRES History 220 References 228 Index 231 List of Figures 1 1 1 2 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 2 10 2 11 2 12 2 13 2 14 2 15 2 16 2 17 2 18 2 19 2 20 3 1 3 2 3 3 3 4 4 1 4 2 Structure of AIRES simulation program oaoa e 7 Stack entries versus thinning level ooa aaa ee ee eee 10 AIRES coordinate system ooa 12 Mean molecular weight of the atmosphere versus altitude oaoa aoaaa 14 Density of air versus altitude ooa ee eee 14 Vertical atmospheric depth versus altitude o oo aa 1
284. uced by A M Hillas 4 1 and was implemented modularly as a procedure which is independent of the units which manage the physical interactions The original Hillas algorithm and the AIRES extended thinning algorithm are described in the fol lowing sections 2 3 1 Hillas thinning algorithm Let us consider the process A gt B Bo Bn n gt 1 2 20 where a primary particle A generates a set of n secondaries B By Let Ea Epg be the energy of A Bi and let Ey be a fixed energy called thinning energy Before incorporating the secondaries to the simulating processes the energy E4 is compared with Ern and then e If E4 gt E every secondary is analyzed separately and accepted with probability 1 if Ep gt Ep Pekin 2 21 Bi if Ep lt Em th e If E4 lt Er that necessarily means that the primary comes from a previous thinning op eration In this case only one of the n secondaries is conserved It is selected among all the secondaries with probability p i 2 22 j 1 B This means that once the thinning energy is reached the number of particles is no more in creased The procedure actually used in AIRES implements this step in a technically different way but retrieving statistically equivalent results CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 29 In both cases the weight of the accepted secondary particles is equal to the weight of particle A multiplied by the inverse of
285. um parameter Nmax If no fit was possible then the value coming from a direct estimation from the input data is returned xmax Output double precision Fitted position of the shower maximum Xmax in g cm If no fit was possible then the value coming from a direct estimation from the input data is returned x0 Output double precision Fitted position of the point where the Gaisser Hillas function is zero parameter Xo expressed in g cm lambda Output double precision Fitted parameter in g cm sqsum Output double precision The resulting normalized sum of squares 1 ON No i NCH ay S NN Nas N CH i D 1 where N is the number of data points used in the fit and NC N G4 represent the set of particle numbers given as input returned from equation 4 1 for the corresponding depths irc Output integer Return code Zero means that the fit was successfully completed 172 APPENDIX D THE AIRES OBJECT LIBRARY getcrorecord FORTRAN okflag getcrorecord channel intfields realfields altrec vrb irc C okflag getcrorecord amp channel amp intfields 1 amp realfields 1 amp altrec amp vrb amp irc Reading a record from a compressed data file already opened This routine can be used to read records from every kind of compressed file The routine automatically processes the records without needing any user level specification beyond file identity parameter channel T
286. up W5013 1994 34 Particle Data Group D E Groom et al The European Physical Journal C15 1 2000 web site www pdg 1b1 gov Index Page numbers in boldface represent the definition or the main source of information about whatever is being indexed ADF or adf see internal dump file portable format AIRES history 220 installation 9 109 table of features 4 AIRES coordinate system 11 12 19 62 72 74 76 129 199 201 202 207 208 AIRES file directories 60 export directory 60 60 121 global directory 60 107 121 output directory 60 121 scratch directory 60 60 121 working directory 60 60 103 104 115 124 AIRES IDF to ADF converting program 5 107 108 223 224 AIRES object library 2 75 83 94 112 144 221 222 224 225 C interface 94 144 cioclose 98 145 cioclosel 98 145 ciorinit 94 99 146 ciorshutdown 98 147 clockrandon 148 197 crofieldindex 99 149 crofileinfo 97 150 crofileversion 96 151 crogotorec 100 144 152 croheaderinfo 96 153 croinputdata0 96 154 169 187 crooldata 100 156 croreccount 98 157 crorecfind 100 158 crorecinfo 98 159 crorecnumber 100 160 crorecstrut 97 161 crorewind 100 162 crospcode 84 100 163 231 crospmodinfo 100 164 crospnames 165 crotaskid 96 166 dumpfileversion 97 167 dumpfileversiono 168 dumpinputdata0 97 169 fitghf 100 170 getcrorecord 97 99 172 181 getcrorectype 100 174 getglobal
287. v Re 2 p 2 1 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 13 where p x y and ze z denotes the point s central altitude an alternative way to express the z coordinate which stresses the fact that this coordinate is always measured along the same central axis The redundant set of coordinates x y Bey Ze 2 2 is used by AIRES to define the position of a point The difference between z and zy gives information about how far from the z axis is the point and in the plane Earth zone z is set equal to ze This way of taking into account the Earth s shape in the simulations proved to be accurate enough when compared with exact procedures while being economic from the computational point of view as shown in section 1 2 page 9 2 1 2 Atmosphere The Earth s atmosphere is the medium where the particles of the shower propagate and their evolution depends strongly on its characteristics The simulations must therefore be based on realistic models of the relevant atmospheric quantities The atmosphere has been extensively measured and studied during the last decades As a result a variety of models and parameterizations of measured data have been published Among them the so called US standard atmosphere 13 is a widely used model based on experimental data We have selected it as a convenient model to use in AIRES which gives an acceptably realistic approximation of the average atmosphere An evident charact
288. vant observable to study is the distribution in time of the different particles that arrive at ground level In figure 2 17 the mean arrival delay time At is plotted as a function of the lateral distance The arrival time delay for each particle is the difference between the absolute arrival time and a global time t defined as the time required by light to go from the injection point the top of the atmosphere is this example to the ground surface traveling along the shower axis In a vertical shower all the delays are positive To obtain the average values plotted in figure 2 17 all the times corresponding to particles reaching ground around a certain distance r to the shower core are added up and divided by the corresponding number of particles Two well known characteristics of the time distribution can clearly be seen from the plots of figure 2 17 i The mean time delays are larger than the ones corresponding to a spherical front with 40 CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 3000 lt At gt ns 2500 2000 1500 1000 500 2 3 Figure 2 17 Mean arrival o w time distributions for 107 distance from the core m eV vertical proton showers center at the first interaction point ii In average muons arrive first then electrons and positrons and finally gammas Non vertical showers present particular characteristics that merit a separate analysis In figure 2 18 the lateral distribution of gammas electrons
289. ve belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES MFPThreshold Syntax MEPThreshold energy Default MFPThreshold 50 GeV s h Threshold energy for the currently effective mean free paths All hadronic collisions with energy greater than or equal to this threshold will be processed using the current mfp parameterization that can be set using directive MFPHadronic otherwise standard MFP s will be used energy must be greater than or equal to 200 MeV This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES MinExtCollEnergy Syntax MinExtCollEnergy energy Default MinExtCollEnergy 200 GeV for the SIBYLL model MinExtCollEnergy 80 GeV for the QGSJET model s h Threshold energy for invoking the external hadronic collision routine if enabled energy must be greater than or equal to 25 GeV This directive belongs to the model dependent IDL instruction set and may be changed or not implemented in future versions of AIRES MinExtNucCollEnergy Syntax MinExtNucCollEnergy energypernucleon Default MinExtCollEnergy 200 GeV for the SIBYLL model MinExtCollEnergy 80 GeV for the QGSJET model s h Threshold energy per nucleon for invoking the external nucleus nucleus collision routine if enabled energypernucleon must be greater than or equal to 25 GeV This directive has no effect on simul
290. vertical atmospheric depths Whenever necessary AIRES transforms lengths into vertical depths and vice versa using the current atmospheric model Notice that the vertical altitudes are equal to the corresponding z coordinates only for points located in the z axis To illustrate this point let us consider the following instructions InjectionAltitude 100 km GroundAltitude 1000 m PrimaryZenAngle 60 deg With such specifications the primary particles will be injected at an altitude of 100 km above sea level measured along the vertical passing by the injection point Taking into account that the shower axis has an inclination of 60 degrees and applying equation 2 1 it is possible to calculate the z coordinate of the injection point also referred as central injection altitude In this case the result is Ze 17962 m The positions of the observing levels defined in section 2 2 3 page 26 can be set using Observ ingLevels This directive has two different formats i ObservingLevels N with N an integer not less than 4 In this case the positions of the observing levels are set taking into account the injection and ground vertical depths Let X X be the injection ground depth then the spacing between observables and the positions of the first and last observing levels are set via X X AX No 1 5 W X AX l Mhs SNK ii ObservingLevels No Xa Xo with N an integer not less than 4 and Xa and Xp valid vert
291. ving levels N gt 1 and xf x is the vertical depth of the first last observing level oy lt x then the vertical depth of the other observing levels is given by x6 yo No 1 2 19 x xM 4 i 1 AX i 1 No Notice that the first observing level is that of highest altitude The Landau Pomeranchuk Migdal LPM effect 19 24 25 is an example of such kind of processes The LPM effect implies a reduction of the cross section of e y processes at very high energies In AIRES it is implemented as a corrective algorithm whose effect is that of rejecting a fraction of the previously approved processes As a result the correct cross sections are statistically preserved Unstable particles are forced to decays CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 27 e Charged particles that move across the air For such particles the continuous energy losses by ionization of the medium are evaluated and recorded The data collected by the monitoring routines are used to evaluate different kind of observables for example Longitudinal development of the shower Tabular data giving the number and energy of particles crossing each defined observing levels Shower Maximum The data collected for the longitudinal development of all charged particles are used to estimate the shower maximum Xmax that is the vertical depth of the point where the number of charged particles reaches its maximum see section 4 1 1 Lateral di
292. vision of the electromagnetic shower engine The thinning algorithm possess now two maximum weight parameters respectively for elec tromagnetic y e e7 and heavy particles New IGRF 2000 data set used to estimate geomagnetic field 48 new longitudinal development tables corresponding to the following observables Number of low energy particles versus atmospheric depth Energy of low energy particles versus atmo spheric depth deposited energy ionization versus atmospheric depth Improved procedure for updating idf and compressed files that permits more stable operation during very long runs Many new modules in the AIRES library 222 APPENDIX F AIRES HISTORY 14 Global variables can be defined within the input data Such variables can be used for text re placement within the input file and or be passed to external analysis or special primary modules 15 New length inches feet yards and miles and energy Joules units supported The standard keV replaces the old KeV which is maintained as valid for backwards compatibility 16 Additionally lots of minor changes improvements and of course corrections of bugs AIRES version 2 2 1 23 Dec 1999 Functionally equivalent to version 2 2 0 A bug in the QGSJET interface Diffractive interactions were mistakenly disabled has been fixed AIRES version 2 2 0a 26 Nov 1999 Functionally equivalent to version 2 2 0 A bug in the recently developed interface for pro
293. voking the simulation program The existence of the BeforeProcess macro is checked in the working directory and in the user s account HOME directory in that order If the file is found it is executed CHAPTER 5 THE AIRES RUNNER SYSTEM 105 The complete command line used when invoking the BeforeProcess macro is the following BeforeProcess_ spool tn trial ifile prog where spool is the spool identification tn is the task name or UNKNOWN if the task is not initialized yet trial is a numeric variable counting the number of trials for the current run Generally takes the value 1 but in certain circumstances for example when relaunching AIRES after a system crash it can take larger values ifile is the name of the input file to be used when running the simulation program prog is the instruction used to invoke AIRES which includes the full name of the simulation program used in the next run After completing execution of the BeforeProcess macro the ARS checks the corresponding re turn code continuing with the next step only if it is zero 5 3 Concurrent tasks In many cases it is necessary to simultaneously process more than one task Systems having more than one CPU and or clusters of machines sharing the same file system are examples of such situation The AIRES Runner System provides certain tools designed to work under such circumstances The key idea is to define more than one spool and assign one spool to each processin
294. wer Notice that near the ground level the number of muons the next most numerous particles is nearly two orders of magnitude smaller than the number of electrons and positrons The number of ground pions and kaons are even smaller but at high altitudes these particles represent an important fraction of all the particles of the shower they can be even more numerous than the muons This is consistent with the fact that the hadronic interactions producing lots of secondary pions and kaons take place at the early stages of the shower development AIRES simulation engine also records the energy carried by the different particles that cross each observing level These energy longitudinal development data are plotted in figure 2 14 and correspond to the same set of showers used for the previous figures The all particles plot gives the total energy carried by the tracked particles crossing every ob serving level Since neutrinos are not tracked their energy is not included At high altitude the medium energy losses are not important and therefore the total energy carried by the shower par ticles remain constant But the available energy begins to diminish as long as such losses increase this event being correlated to the growth of the electromagnetic part of the shower In the case being considered the energy recovered at ground level is about 44 of the primary energy This figure should be taken only as a qualitative measure of the recovered
295. will eventually interact similarly as the primary did generating new sets of secondaries This multiplication process continues until a maximum is reached After that moment the shower begins to attenuate because an increasing number of secondaries are produced with energies too low for further particle generation This phenomenon is simulated in AIRES in the following way 1 Several data arrays or stacks are defined Every record within any stacks is a particle entry and represents a physical particle The data contained in every record are related to the characteris tics of the corresponding particle Identity position energy etc 2 The particles can move inside a volume within the atmosphere where the shower takes place This volume is limited by the ground and injection surfaces and by vertical planes which limit the region of interest 3 Before starting the simulations all the stacks are empty The first action is to add the first stack entry which corresponds to the primary particle The primary is initially located at the injection surface and its downwards direction of motion defines the sower axis 6 CHAPTER 1 INTRODUCTION 4 The stack entries are repeatedly processed sequentially Every particle entry is updated analyz ing first all the possible interactions it can have and evaluating the corresponding probabilities for each possibility taking into account the physics involved 5 Using a stochastic method the mentione
296. xed energy equal to this parameter Otherwise the energy will be sampled from the interval Emin Emax minener maxener with the probability distribution of equation 3 2 with exponent y option ally specified by gamma The primary energy must be larger than 500 MeV and less than 1014 GeV 107 eV There are no restrictions on y If not specified it is set to 1 7 PrimaryParticle Syntax PraimaryParticle particle weight Default None This directive is always required s Primary particle specification particle is the particle name Proton Iron Fe 56 etc are valid particle names Special particle names defined by means of directive AddSpecialParticle can also be used with this instruction If more than one PrimaryParticle directive appear within the input instructions then the primary particles will be selected at random among the different specified particle kinds with probabilities proportional to the weights specified in the corresponding weight fields If weight is not specified then the particle weight is taken as 1 130 APPENDIX B IDL REFERENCE MANUAL Primary ZenAngle Syntax PxrimaryZenAngle minang maxang S SC CS Default PrimaryZenAngle 0 deg s Primary zenith angle O If only minang is specified then the zenith angle is fixed and equal to this value and the default for the azimuth angle will be 0 Otherwise the zenith angle for each shower is selected randomly within the interval minang maxang with t
297. y of Linsley s parameterization is that X h can easily be inverted to obtain h X7 X X gt 0 Let X Xs h l 1 L then Xs o In Ka RSM IS L 1 h by 2 7 cLlar X br 0 lt X lt Xz These coefficients correspond to the default setting and are coincident with the ones used in the program MOCCA 1 In the current version of AIRES an alternative set of coefficients corresponding to a South Pole atmosphere is also available CHAPTER 2 GENERAL CHARACTERISTICS OF AIRES 17 Layer Layer limits km ay bi c l From To g cm g cm m 1 0 4 186 5562 1222 6562 9941 8638 2 4 10 94 9199 1144 9069 8781 5355 3 10 40 0 61289 1305 5948 6361 4304 4 40 100 0 0 540 1778 7721 7016 5 100 113 0 01128292 1 107 Table 2 1 Linsley s model coefficients for the US standard atmosphere 16 The number of layers is L 5 where the replacement X hz 1 0 has been made A quantity related to the vertical depth that appears frequently in air shower calculations is the slant atmospheric depth Xs defined similarly as X equation 2 4 but using a non vertical inte gration path In most applications the integration path is a straight line going along the shower axis from the given point to infinity In this case X takes the form 1 X z f p z dl 2 8 where the prime in the integral indicates that the path is along a non vertical line and z is the vertical altitude defined in equation 2 1
298. y one of the tables listed in appendix C page 137 Let us consider 3Our definition of the Gaisser Hillas function involves vertical depths Some authors however use slant depths instead Both definitions can be used to parameterize the shower profile Furthermore notice that in the plane Earth approximation both vertical and slant forms are equivalent provided the parameters are adequately interpreted that is taking into account the factor cos of equation 2 9 If the Earth s curvature is taken into account the translations between vertical and slant quantities must be done numerically see pages 17 and 214 In AIRES 1 2 0 a 3 parameter fit is made is kept fixed with an externally given value of 70 g cm The 4 parameter fitting algorithm currently used includes substantial improvements that increment the goodness of the fits for a variety of shower profiles whilst maintaining stable the fitting procedure The depth Xo refers to the point where the Gaisser Hillas function is zero and is not equal and not even necessarily related to the depth of the first interaction noted X in this manual 80 CHAPTER 4 MANAGING AIRES OUTPUT DATA for instance the following IDL instructions Task mytask Summary Off Export 1205 1211 Export 1293 Option a Export 2001 Options ds Export 2791 2793 Options ML End Here mytask is a string that represents an already finished or currently running task The Summ
299. y to access information that can be stored only in the internal dump file In these cases it can be helpful to invoke the routine loadumpfile right after CHAPTER 4 MANAGING AIRES OUTPUT DATA 97 opening the corresponding compressed file and then use some of the routines dumpinputdata0 dumpfileversion etc to access the mentioned data The structure of any already opened file can be printed calling routine crofileinfo which prints a list of the different records defined for the corresponding file and the names of the fields within records It is also possible to load into arrays such information by means of routine crorecstrut in order to make it available to the analysis program Reading the data records Once a file is open it remains positioned at the beginning of the compressed data section From then on the file can be sequentially read using routine getcrorecord okflag getcrorecord channel indata fldata altrec 0O irc getcrorecord returns logical data which in this case are stored in the logical variable ok flag The returned value is true if the reading operation was completed successfully false otherwise end of file I O error etc ciochann should be the same integer variable used when opening the file it identifies the file to be processed irc is an integer return code If okflag is false then the return code contains information about the error that generated the abnormal return as expla

AIRES user`s manual and reference guide

Contents

Download Pdf Manuals

Related Search

Related Contents