BDSIM User's Manual v0.6
Contents
1. yp mrad z cm E MeV option nlinesIgnore 0 Note currently this distribution only works when bdsim is executed in the directory of the userfile There are examples for all distribution types in bdsimsource test BDSBunchTestFiles In alternative one can pass to the simulation a file containing a list of particles to be generated For more details see Appendix C Bunch description formats page 36 DEP RECATED 3 4 3 sample and csample To record the tracking results one uses the sample and csample commands To insert a sampling plane before element the following command should be used sample range lt element gt Example sample range d Chapter 3 Lattice description 23 To put a cylindrical sampler of length 10 in m around element element at distance ro in m the following command should be used csample range lt element gt r r0 1 10 Samplers output the following parameters at the specified location E Energy GeV EO Energy at last scatter Gev X Global X position S path length Y Global Y position t time of flight Z Global Z position t0 time of flight at last scatter Xp Global angle in x z trackID trackID of particle Yp Global angle in y z weight weight of track Zp 1 sqrt Xp Yp parentID trackID of parent particle x Relative x position x0 x at last scatter y Relative y position y0 y at last scatter Z Relative z position z0 z at last scatter xp Relative angle in x z xp0 x2. 1 2 elements of sigma matrix this overwrites sigmaX sigmaXp sigmaY sigmaYp sigmaE and sigmaT vari ables if they have been defined previously It will also recalculate the Twiss parameters e sigmaMN cmn in m where M range between 1 and 6 and N ranges between M and 6 6 distrType eshell a thin elliptic shell locus in x x and y y with given semiaxes e shellX radius in m e shellXp radius in rad e shellY radius in m e shellYp radius in rad e sigmaE in GeV The width of shell can also be specifed via the following parameters e shellXWidth absolute width in m e shellXpWidth absolute width in rad e shellYWidth absolute width in m e shellYpWidth absolute width in rad If left unspecified these default to 0 and therefore the shell is infinitely thin Partilces are uniformly distributed in this width T distrType ring in the x y plane the particles are uniformly distributed in r and in inside a ring with inner radius Rmin and outer radius Rmax x y and time are exactly XpO YpO and TO respectively for each generated particle The kinetic energy distribution is a gaussian of width sigmaE centered about the nominal beam kinetic energy e Rmin Rmax inner and outer radius in m e sigmaE RMS energy spread GeV 8 distrType circle filled circle in both x x and y y planes with uniform distribu tion in all dimensions The input parameters specify a radius R that is the
3. CREATE DATABASE DATABASE_NAME USE DATABASE_NAME A table must be created to allow for the insertion of the geometry descriptions A table is created using the following MySQL compliant commands CREATE TABLE TABLE NAME_GEOMETRY TYPE TABLE PARAMETER VARIABLE TYPE TABLE PARAMETER VARIABLE TYPE TABLE PARAMETER VARIABLE TYPE 23 Once a table has been created values must be entered into it in order to define the solids and position them The insertion command must appear after the table creation and must the MySQL compliant table insertion command INSERT INTO TABLE NAME_GEOMETRY TYPE VALUES value1 value2 char value Sr Appendix A Geometry description formats 29 The values must be inserted in the same order as their corresponding parameter types are described in the table creation Note that ALL length types must be specified in mm and that ALL angles must be in radians An example of two simple boxes with no visual attributes set is shown below The first box is a simple vacuum cube whilst the second is an iron box with length x 10mm length_y 150mm length z 50mm positioned at x 1m y 0 z 0 5m and with zero rotation CREATE TABLE mytable BOX NAME VARCHAR 32 MATERIAL VARCHAR 32 LENGTHX DOUBLE 10 3 LENGTHY DOUBLE 10 3 LENGTHZ DOUBLE 10 3 POSX DOUBLE 10 3 POSY DOUBLE 10 3 POSZ DOUBLE 10 3 ROTPSI DOUBLE 10 3 ROTTHETA DOUBLE 10 3 ROTPHI DOUBLE 10 3 INSERT INTO mytable BOX VALU
4. If supplied then the object will be set up to produce the appropriate magnetic field using the supplied K1 or K2 table parameter values Three magnet types are available QUAD SEXT and OCT The default is set to no magnet type Note that if MAGTYPE is set to a value whilst K1 K2 K3 are not set then no magnetic field will be implemented e K1 Variable type DOUBLE 10 3 This is an optional parameter If set to a value other than zero in conjunction with MAGTYPE set to QUAD then a quadrupole field with this K1 value will be set up within the object Default is set to zero e K2 Variable type DOUBLE 10 3 This is an optional parameter If set to a value other than zero in conjunction with MAGTYPE set to SEXT then a sextupole field with this K2 value will be set up within the object Default is set to zero e K3 Variable type DOUBLE 10 3 This is an optional parameter If set to a value other than zero in conjunction with MAGTYPE set to OCT then a sextupole field with this K3 value will be set up within the object Default is set to zero e POSX POSY POSZ Variable type DOUBLE 10 3 These are required parameters They are form the position in mm used to place the object in the component volume POSX and POSY are defined with respect to the center of the component volume and with respect to the component volume s rotation POSZ is defined with respect to the start of the component volume Note that if th
5. are gas at T 300K p 10 bar both Air and Vacuum are a N 80 O 20 mixture CarbonMonoxide is composed of CO molecules There are also predefined elements i e atoms that can be used for building composite materials H He Be on N Kou Al Si pu S Ca wt yu Mn Fe Co Ni Cu Nb Sm yW Pb For more details see the file src BDSMaterials cc or run the command bdsim materials from the command line 3 4 Run control and output The execution control is performed in the GMAD input file through option and sample commands How the results are recorded is controlled by the sample command When the Chapter 3 Lattice description 17 visualization is turned on it is also controlled through Geant4 command prompt 3 4 1 option Most of the options in bdsim are set up by the command option lt name gt value x The following options influence the geometry beampipeRadius beampipeThickness beampipeMaterial apertureType aperi aper2 aper3 aper4 boxSize vacuumMaterial vacuumPressure buildTunnel buildTunnelFloor tunnelRadius tunnelThickness tunnelSoilThickness tunnelMaterial soilMaterial tunnelOffsetX tunnel0ffsetY tunnelFloor ffset samplerDiameter blmRad blmLength includeIronMagFields default beampipe outer radius m default beampipe thickness m default beampipe material aperture model to use one of circular rectangular and
6. between them A 2 mokka As well as using the GMAD format to describe user defined physical geometry it is also possible to use a Mokka style format This format is currently in the form of a dumped MySQL database format although future versions of BDSIM will also support online querying of MySQL databases Note that throughout any of the Mokka files a may be used to represent a commented line There are three key stages which are detailed in the following sections that are required to setting up the Mokka geometry e Describing the geometry e Creating a geometry list e Defining a Mokka Element to load geometry descriptions from a list A 2 1 Describing the geometry An object must be described by creating a MySQL file containing commands that would typically be used for uploading creating a database and a corresponding new table into a MySQL database BDSIM supports only a few such commands specifically the CREATE TABLE and INSERT INTO commands When writing a table to describe a solid there are some parameters that are common to all solid types such as NAME and MATERIAL and some that are more specific such as those relating to radii for cone objects A full list of the standard and specific table parameters as well as some basic examples are given below with each solid type All files containing geometry descriptions must have the following database creation commands at the top of the file DROP DATABASE IF EXISTS DATABASE_NAME
7. collimator the aperture is an ellipse the external profile in the transverse plane is a square Here again the longitudinal collimator structure is not taken into account Attributes e 1 length m default 0 e xsize horizontal aperture m default set to boxSize e ysize vertical aperture m default set to boxSize e outR limits external extent m in x and y of the collimator default set to boxSize e material collimator material default set to Graphite Example col2 ecol 1 0 4 m xsize 2 mm ysize i mm material W 3 3 14 muspoiler muspoiler defines a muon spoiler which is a rotationally magnetised iron cylinder with an inner radius outer radius magnetic field strength and length Attributes e 1 length m default 0 e B magnetic field T default set to 1 e boxSize the full width of the magnet outer volume m e additionally all of the drift parameters Example muspi muspoiler 1 5 m inR 1 cm outR 60 cm B 1 5 3 3 15 solenoid solenoid defines a solenoid manget with a uniform magnetic field parallel to the beam propagation axis Attributes e 1 length m default 0 e ks solenoid strength ks Bo Bp e boxSize the full width of the magnet outer volume m e additionally all of the drift parameters Note this is still under development For particles with large transverse momentum s component of unit momentum vector 0 8 a Geant4 Runge Kutta integrator
8. element can be used as a new element type The child element will have the attributes of the parent q quadrupole l 1 m k1 0 1 qq q k1 0 2 3 3 1 Coordinate system The usual accelerator coordinate system is assumed see 3 3 3 2 Units In GMAD the SI units are used length m metres time s seconds angle rad radians quadrupole coefficient m multipole coefficient 2n poles m electric voltage MV Megavolts electric field strength MV m particle energy GeV particle mass GeV c particle momentum GeV c beam current particle charge emittances density temperature pressure mass number A Amperes e elementary charges pi m mrad g cm K Kelvin atm atmosphere g mol There are some predefined numerical values are pi 3 14159265358979 GeV 1 eV 10 keV 1076 MeV 10 3 4 see add var in parser gmad cc m 1 cm 107 mm 107 um 1076 Chapter 3 Lattice description 7 TeV 10 nm 107 MV 1 S 1 Tesla 1 ms 107 rad 1 us 1076 mrad 107 ns 10 clight 2 99792458 x 108 for example one can write either 100 eV or 0 1 keV when energy constants are con cerned 3 3 3 marker marker has no effect no volume is associated to it but allows one to identify a position in the beam line say where a sampler will be placed It has no attributes Example mi marker 3 3 4 drift drift defines a straight section of beampipe with no magnetic field Its volume
9. parameter This value will be used to specify the z extent of the box s dimensions A 2 1 4 Cone Solid Types Append _CONE to the table name in order to make use of the G4Cons solid type The following table parameters are specific to the cone solid LENGTH Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the z extent of the cone s dimensions RINNERSTART Variable type DOUBLE 10 3 This is an optional parameter If set then this value will be used to specify the inner radius of the start of the cone The default value is zero RINNEREND Variable type DOUBLE 10 3 This is an optional parameter If set then this value will be used to specify the inner radius of the end of the cone The default value is zero ROUTERSTART Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the outer radius of the start of the cone ROUTEREND Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the outer radius of the end of the cone STARTPHI Variable type DOUBLE 10 3 This is an optional parameter If set then this value will be used to specify the starting angle of the cone T he default value is zero DELTAPHI Variable type DOUBLE 10 3 This is an optional parameter If set then this value will be used to specify the delta angle of the cone The default value is 2 PI A 2 1 5 Torus S
10. physicsList option in the input file e g option physicsList em standard Several predefined physics lists are available Some physics lists allow biasing and re weighting for some processes e g muon production To set the amount of biasing see Section 3 4 1 option page 17 Further details of the QGSP FTFP and BERT hadronic physics lists can be found in 5 standard em standard em low em muon lw merlin hadronic standard hadronic muon hadronic QGSP BERT hadronic QGSP BERT muon hadronic QGSP BERT HP muon transportation of primary particles only transportation of primary particles bremsstrahlung Cerenkov multiple scattering ionization the same but using low energy electromagnetic models em standard plus muon production processes with biased muon cross sections list for laser wire simulation standard electromagnetic physics and laser wire physics which is Compton Scattering with total cross section renormalized to 1 transportation of primary particles and the following pro cesses for electrons multiple scattering ionisation and bremsstrahlung em standard plus fission neutron capture neutron and pro ton elastic and inelastic scattering hadronic standard plus muon production processes with bi ased muon cross sections em standard plus hadron physics using the quark gluon string plasma QGSP model and the Bertini cascade model BERT hadron QGSP BERT plus muon prod
11. same for both x x and y y but it is denoted in input as X e envelopeX radius in x y in m e envelopeXp radius in x y in rad e envelopeT full width in time in s e envelopeE full width in energy in GeV 9 distrType square similar to circle a filled square in both x x and y y planes with uniform distribution in all dimensions The input parameters specify the envelope e envelopeX half width of square in x in m e envelopeXp half width of square in x in rad e envelopeY half width of square in y in m Chapter 3 Lattice description 22 e envelopeYp half width of square in y in rad e envelopeT full with in time in s e envelopeE full width in energy in GeV 10 distrType userfile user defined file format and list of particles in ascii text file e distrFile string must be in inverted commas filename where particles are listed e distrFileFormat string specifying columns in text file You must also specify the general option in your gmad file ie not under beam option nlinesIgnore N where N is the integer number of liens to ignore in the file for header purposes default 0 Examples beam particle et energy 100 MeV distrType gauss sigmaX 0 01 sigmaXp 0 1 sigmaY 0 01 sigmaYp 0 1 beam particle e energy 1 GeV distrType userfile distrFile 9 UserFile dat distrFileFormat x mum xp mrad y mum
12. 16 element Rire TEET ENSA adda kee 12 9 9 10 JETHO en ere ge ns 13 9 9 20 diatdef cvs ve bead pid hed eed herbed da ve hee URBES 13 Doel laseren n E E RTE EERE G 15 d 9 22 BAS cents eni e a aea d DX amp aaa a e 15 3 9 29 spec keyword easiest erener bes meri eo ee hee n 15 3 3 24 Element number 00 cece cece eee eee eee eee 15 3 3 25 Element attributes 0 0 0 eee 16 3 3 26 Editing apertures 00 cece eee ene eee eens 16 3 3 27 Material table 0 cece eee eee 16 3 4 Run control and output 0 0 16 BAe OptlOni i sesheseerbteseessrereetesee t eee ka ke dada es I7 342 DeiM recaen pahe e air EE Ea E a EE 19 3 4 3 sample and csample cee cece eee ddira 22 DAA dumpisiiissses t periere r aeee T Pisa id a A 23 DAD USE eiea PPP pus E de CEMELR wie Der eR iege 23 34L 0 print seeeck ge we Va Ape ieee ny ee ar 23 4 VisualiZatlOMlo siad Ede bs a Eie 24 S PHYSICS ee boone he bed ee a E 25 5 1 physicsList option 00 c eee reren seris 25 D2 Transportat enrete ni eee dee epRURERRRNERECSEpe Reerrirrs 26 5 3 Tracking accuracy 2 00 ccc eee eee nett e ene ne 26 6 Output Analysis e ess 26 Appendix A Geometry description formats 27 AT usd Tolle esset pen ODE REFERO aon Era sake qued eu dad 27 A2 mokke adag sadn dX a E RO Ed Ce Re RE RR do 28 A 2 1 Describing the geometry ssesssssesees eee eee 28 A 2 1 1 Common Table Pa
13. BDSIM User s Manual v0 6 I Agapov S T Boogert L C Deacon S Malton L Nevay J Snuverink revision 0 6 last updated 22 May 2015 Table of Contents BDSIM v0 6 User s Manual 1 1 About BDSIENL een kn ENERO ERG 1 2 Obtaining Installing and Running 1 3 Lattice description 005 2 9 1 Program str cetur amp os dose cod ke bhrpee he aud VE ER E eura 3 3 2 Arithmetical expressions sssseseesses en 3 3 3 Physical elements and Entities 0 00 cece eee eee 4 3 3 1 Coordinate system 0 6 cee es 6 nno MEET D EE 6 39 0 f l BEKOE suec oen E eee ake e er ep RE Robe ondes 7 E HITE NL T Dah TOODA esee xe AREER AANEEN ANNEE A nM RE Ed 7 9 9 0 sSbend o ilie sies UE ed ee Pas Uieeeas Lovaas eee 8 39 quadr polessooeneissseks fe ee oad avid a Pp e eie tee isis eS 8 9 9 9 SECXtUPOLS 1hiceccnccassvisvedadubhe aabths e ek Gg dar peda 9 3 9 9 OCTUPOL S eek heben sad cus Ree pb oie eee 9 33 10 mulbtipole i ee e max see an rr e rado yE ES P ER Debs 9 D 11 SET teddies oi sek URS IRAE ERE geen t dp ES paries 10 9 9 12 ECOIsc Leere rede ehe EVA Pe Le ES Hes 10 o 9 135 OCOl sii seth pepe PERDER EAA doen coe ool eves QE is 11 34 14 m spoiler eec i arun REP ENEA RR rx LEE 1i gdo Solenoldo p cia diets PANANET PIU CORE INR 11 3 3 16 hkick and VRICK 22006 sce een whee Rer Sera ees 12 33 17 transform3d neues p RE E Ru ERREUR as 12 9 9
14. ES a_box vacuum 50 0 50 0 50 0 0 0 0 0 0 0 0 0 0 0 0 0 INSERT INTO mytable BOX VALUES another box iron 10 0 150 0 50 0 1000 0 0 0 500 0 0 0 0 0 0 0 Further examples of the Mokka geometry implementation can be found in the exam ples Mokka General directory See the common table parameters and solid type sections below for more information on the table parameters available for use A 2 1 1 Common Table Parameters The following is a list of table parameters that are common to all solid types either as an optional or mandatory parameter Appendix A Geometry description formats 30 e NAME Variable type VARCHAR 32 This is an optional parameter If supplied then the Geant4 LogicalVolume associated with the solid will be labelled with this name The default is set to be the table s name plus an automatically assigned volume number e MATERIAL Variable type VARCHAR 32 This is an optional parameter If supplied then the volume will be created with this material type note that the material must be given as a character string inside double quotation marks The default material is set as Vacuum e PARENTNAME Variable type VARCHAR 32 This is an optional parameter If supplied then the volume will be placed as a daughter volume to the object with ID equal to PARENTNAME The default parent is set to be the Component Volume Note that if PARENTID is set to the Component Volume then POSZ will be defined w
15. This is an optional parameter If set then this value will be used to specify the delta angle of the polycone The default value is 2 PI A 2 1 7 Elliptical Cone Solid Types Append _ELLIPTICALCONE to the table name in order to make use of the G4Ellipticalcone solid type The following table parameters are specific to the elliptical cone solid e XSEMIAXIS Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the Semiaxis in X e YSEMIAXIS Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the Semiaxis in Y e LENGTHZ Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the height of the elliptical cone e ZCUT Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the upper cut plane level Note that the above parameters are used to define an elliptical cone with the following parametric equations in the usual Geant4 way x XSEMIAXIS LENGTHZ u u Cos v Y YSEMIAXIS LENGTHZ u u Sin v z u where v is between 0 and 2 PI and u between 0 and h respectively A 2 2 Creating a geometry list A geometry list is a simple file consisting of a list of file names that contain geometry descriptions This is the file that should be passed to the GMAD file when defining the Mokka element An example of a geometry list containing boxes sql and cones sql
16. ameters and other options with beam and option commands The sample and csample commands control what sort of information will be recorded during the execution The parser is case sensitive However for convenience of porting lattice descriptions from MAD the keywords can be both lower and upper case The GMAD language is discussed in more detail in this section 3 2 Arithmetical expressions Throughout the program a standard set of arithmetical expressions is available Every expression is ended with a semicolon for example x 1 y 2 5 x z sin x log y 8e5 Available binary operators are Available unary operators are Available Boolean operators are gt lt gt lt gt Available functions are e sqrt 3 see add func in parser gmad cc Chapter 3 Lattice description 4 e cos e sin e exp e log e tan e asin e acos e atan e abs 3 3 Physical elements and Entities GMAD implements almost all the standard MAD elements but also allows to define ar bitrary geometric entities and magnetic field configurations The geometry description capabilities are extended by using drivers to other geometry description formats which makes interfacing and standardisation easier The syntax of a physical element declaration is element_name element_type attributes for example qd quadrupole 1 0 1 m k1 0 01 element_type can be of basic type or inherited Allowed basic t
17. contains only the vacuum beampipe no outer iron cylinder Attributes 1 length m default 0 e aperi aperl m e aper2 aper2 m e aper3 aper3 m e aper4 aper4 m e beampipeMaterial material the beampipe is made of default StainlessSteel e vacuumMaterial material used for the vacuum for example a user defined material defined before this item Example di3 drift 1 0 5 m 3 3 5 rbend rbend defines a rectangular bending magnet Attributes 1 length m default 0 e angle bending angle rad default 0 e B magnetic field T e material the magnet material default set to Iron e ki normal quadrupole coefficient k1 1 Bp dB dx m Positive k1 means hori zontal focusing of positively charged particles default 0 Chapter 3 Lattice description 8 e boxSize the full width of the magnet outer volume m e additionally all of the drift parameters when B is set this defines a magnet with appropriate field strength and angle is not taken into account Otherwise the value of B that corresponds to bending angle angle for a particle with the momentum of the design energy of the model as specified by energy by the beam command is calculated and used in the simulations Example rbi rbend 1 0 5 m angle 0 01 3 3 6 sbend sbend defines a sector bending magnet Attributes 1 length m default 0 angle bending angle rad default 0 e B
18. d about the longitudinal axis clockwise e material the magnet material default set to Iron e boxSize the full width of the magnet outer volume m e additionally all of the drift parameters Example mul multipole 1 0 5 m knl 0 0 1 ksl 0 0 0 Note that both kn1 and ks1 are required and must contain the same number of param eters 3 3 11 rf rfcavity defines an rf cavity Attributes e 1 length m default 0 e gradient field gradient MV m e material the cavity material default set to Iron e boxSize the full width of the magnet outer volume m e additionally all of the drift parameters Example rfi rfcavity 1 5 m gradient 10 MV m 3 3 12 rcol rcol defines a rectangular collimator the aperture is a rectangle the external profile in the transverse plane is a square The longitudinal collimator structure is not taken into account To do this the user has to describe the collimator with the generic type element Attributes e 1 length m default 0 e xsize horizontal aperture m default set to boxSize e ysize vertical aperture m default set to boxSize e outR external extent m in x and y of the collimator default set to boxSize e material collimator material default set to Graphite Example coli rcol 1 0 4 m xsize 2 mm ysize 1 mm material G4_W Chapter 3 Lattice description 11 3 3 13 ecol ecol defines an elliptical
19. e density G4int itsComponents size state temp pressure Then each component is added with a call to the G4Material AddElement G4string G4double method Chapter 3 Lattice description 15 e density density in g cm e T temperature in K default set to 300 e P pressure in atm default set to 1 e state solid liquid or gas default set to solid e components list of symbols for material components e componentsFractions mass fraction of each component in material unit in order Example samarium atom symbol Sm z 62 a 150 4 cobalt atom symbol Co z 27 a 58 93 SmCo matdef density 8 4 temperature 300 0 Sm Co 0 338 0 662 The second syntax can be used also to define materials which are composed by other materials and not by atoms Nb Square brackets are required for the list of element symbols curly brackets for the list of weights or fractions 3 3 21 laser laser defines a drift section with a laser beam inside The laser is considered to be the intersection of the laser beam with the volume of the drift section Attributes e 1 length of the drift section m e x y z components of the laser direction vector e waveLength laser wave length m laserWire laser l 1 um x 1 y 0 z 0 waveLength 532 nm 3 3 22 gas To be implemented in v0 5 3 3 23 spec keyword This was removed in v0 4 and no longer has an effect For setting the ou
20. e object is being placed inside another volume using PARENTNAME then the position will refers to the center of the parent object e ROTPSI ROTTHETA ROTPHI Variable type DOUBLE 10 3 These are optional parameters They are the Euler angles in radians used to rotate the object before it is placed The default is set to zero for each angle e RED BLUE GREEN Variable type DOUBLE 10 3 These are optional parameters They are the RGB colour components assigned to the object and should be a value between 0 and 1 T he default is set to zero for each colour e VISATT Variable type VARCHAR 32 This is an optional parameter This is the visual state setting for the object Setting this to W results in a wireframe displayment of the object S produces a shaded solid and I leaves the object invisible The default is set to be solid Appendix A Geometry description formats 32 FIELDX FIELDY FIELDZ Variable type DOUBLE 10 3 These are optional parameters They can be used to apply a uniform field to any volume with default units of Tesla Note that if there is a solenoid field present throughout the entire element then this uniform field will act in addition to the solenoid field APPROXIMATIONREGION Variable type INTEGER 11 This optional parameter when set to 1 assigns the colume to the approximation region which has its own user defined electromagnetic production cuts see Chapter 5 Physics page 25 Secti
21. e of ellipse of ellipse racetrack 3 horizontal vertical off radius of cir NA offset of set of circle cular part circle octagon 4 x half width y half width angle 1 rad angle 2 rad Currently only circular and rectangular are implemented More models will be completed shortly The outer volume is represented with the exception of the drift element by a cylinder with inner radius equal to the beampipe outer radius and with outer radius given by default by the global boxSize option which can usually be overridden with the outR option In Geant4 it is possible to drive different regions each with their own production cuts and user limits In BDSIM three different regions exist each with their own user defined production cuts see Chapter 5 Physics page 25 These are the default region the precision region and the approximation region Beamline elements can be set to the precision region by setting the attribute precisionRegion equal to 1 For example Chapter 3 Lattice description 6 di drift l 1 m precisionRegion 1 creates a drift element in the precision region Elements in the precision region also retain detailed information about energy deposition every individual hit is stored rather than binned into a histogram The third and final region is the approximation region Volumes within the mokka defined elements can be assigned to this region see Appendix A Geometry page 27 An already defined
22. e will be used to specify the number of z planes to be used in the polycone This value must be set to greater than 1 e PLANEPOS1 PLANEPOS2 PLANEPOSN Variable type DOUBLE 10 3 These are required parameters These values will be used to specify the z position of the corresponding z plane of the polycone There should be as many PLANEPOS parameters set as the number of z planes For example 3 z planes will require that PLANEPOS1 PLANEPOS2 and PLANEPOSS are all set up e RINNER1 RINNER2 RINNERN Variable type DOUBLE 10 3 These are required parameters These values will be used to specify the inner radius of the corresponding z plane of the polycone There should be as many RINNER parameters set as the number of z planes For example 3 z planes will require that RINNER1 RINNER2 and RINNER3 are all set up e ROUTER1 ROUTER2 ROUTERN Variable type DOUBLE 10 3 These are required parameters These values will be used to specify the outer radius of the corresponding z plane of the polycone There should be as many ROUTER parameters set as the number of z planes For example 3 z planes will require that ROUTER1 ROUTER2 and ROUTERS are all set up Appendix A Geometry description formats 35 e STARTPHI Variable type DOUBLE 10 3 This is an optional parameter If set then this value will be used to specify the starting angle of the polycone The default value is zero e DELTAPHI Variable type DOUBLE 10 3
23. efault 1 m standard overall production cuts for positrons default 0 7 mm precision production cuts for positrons in the precision region default 0 7 mm precision production cuts for positrons in the approximation region default 1 m if set Cerenkov radiation is turned on the default predicted range at which a particle is cut Default is 0 7mm the cross section enhancement factor for the gamma to muon process the cross section enhancement factor for the electron positron annihilation to muon process the cross section enhancement factor for the electron positron annihilation to hadrons process Chapter 3 Lattice description 19 useEMLPB if set electromagnetic lead particle biasing is used Default is 0 LPBFraction the fraction of EM processes in which electromagnetic lead particle biasing is used from 0 0 never to 1 0 always The following options influence the generation randomSeed seed for the random number generator setting to 1 uses the system clock to generate the seed ngenerate number of primary particles fired when in batch mode The following options influence the output elossHistoBinWidth bin width in metres for the energy loss histogram sensitiveBeamlineComponents if set energy losses in beamline components are recorded in the energy loss histogram Set by default sensitiveBeamPipe if set energy losses in the beam pipe are recorded in the energy loss histogram Set by default sensitiveBLMs if set ener
24. elliptical Circular is the default aperture parameter 1 m Typically x size aperture parameter 2 m aperture parameter 3 m aperture parameter 4 m default accelerator component full width m the beam pipe gas material default Vacuum which is com posed of 48 2 H 22 196 C and 29 7 O and has a temper ature of 300K the pressure of the beam pipe gas in bar default 1e 12 whether to build a tunnel default 0 whether to add a floor to the tunnel default 0 tunnel radius m the thickness of the tunnel wall m the thickness of the soil surrounding the tunnel m the material of the tunnel default concrete the material of the soil surrounding the tunnel default soil the horizontal offset of the tunnel with respect to the beam line the vertical offset of the tunnel with respect to the beam line the offset of the tunnel floor from the centre of the tunnel the diameter of the sampler planes default is 2 times tunnelRadius the radius of the beam loss monitor cylinders the lengths of the beam loss monitor cylinders whether to include the magnetic fields in the magnet iron default 1 The following options influence the tracking maximumTrackingTime deltaChord deltaIntersection maximum tracking time for entire simulation chord finder precision boundary intersection precision Chapter 3 Lattice description 18 chordStepMinimum lengthSafety minimumEpsilonStep maximumEpsilonStep deltaOneStep m
25. gy losses in the beam loss monitors are recorded in the energy loss histogram Set by default storeTrajectory if set the trajectories are stored in the root file storeMuonTrajectories if set the muon trajectories are stored in the root file storeNeutronTrajectories if set the neutron trajectories are stored in the root file trajCutGTZ do not store any trajectories who end less than this z distance trajCutLTR do not store any trajectories who end outside of this radius Miscellaneous options nperfile number of events recorded per file in ROOT output nlinesIgnore number of lines to skip when reading bunch files For a more detailed description of how the option influence the tracking see Chapter 5 Physics page 25 3 4 2 beam The parameters related to the beam are set with the beam command beam lt name gt value Chapter 3 Lattice description 20 There is a set of predefined distribution types that can be generated In this case one needs to specify the following parameters e particle particle name e et gamma proton etc e energy particle energy e distrType type of distribution and in addition other parameters that depend on the distribution type that has been chosen 1 Global options XO Offset of distribution centre in x m YO Offset of distribution centre in y m ZO Offset of distribution centre in z m XpO Angular offset from nominal axis in x z plane YpO Angular
26. he current scene vis scene add volume Attach the current scene handler to the current scene omittable vis sceneHandler attach Add trajectories to the current scene Note This command is not necessary in exampleNO3 since the C method DrawTrajectory is described in the event action vis viewer set viewpointThetaPhi 90 90 vis drawVolume vis scene add trajectories tracking storeTrajectory 0 vis viewer zoom tracking storeTrajectory 1 for BDS vis viewer zoom 300 vis viewer set viewpointThetaPhi 3 45 By default the macro is read from the file named vis mac located in the current directory The name of the file with the macro can also be passed via the vis mac switch bdsim file line gmad vis_mac my_macro mac In interactive mode all the Geant4 interactive commands are available For instance to fire 100 particles type run beamOn 100 and to end the session type exit Chapter 5 Physics To display help menu help For more details see 1 5 Physics 25 BDSIM can exploit all physics processes that come with Geant4 In addition fast tracking inside multipole magnets is provided More detailed description of the physics is given below 5 1 physicsList option Depending on for what sort of problem BDSIM is used different sorts of physics processes should be turned on This processes are grouped into so called physics lists The physics list is specified by the
27. ibed in this section Examples of input files can be found in the BDSIM distribution in the examples directory In order to convert a MAD file into a GMAD one a utility called mad2gmad sh is provided in the utils directory The following MAD commands are not supported e assign e bmpm e btrns e envelope e optics e title e option e plot e print e return e survey e title The following MAD commands To dump the optical properties of the lattice one can invoke bdsim with the outline file txt outline_type optics options To compute the coordinates of all machine elements in a global reference system one can invoke bdsim with the outline file txt outline type survey options Chapter 3 Lattice description 3 e moni e monitor e wire e prof are replaced with the marker command 3 1 Program structure A GMAD program consists of a sequence of element definitions and control commands For example tracking a 1 GeV electron beam through a FODO cell will require a file like this mk marker qf quadrupole 1 0 5 m ki1 0 1 m 2 qd quadrupole 1 0 5 m ki 0 1 m 2 d drift 1 0 5 m fodo line qf d qd d mk use period fodo beam particle e energy i GeV option beampipeRadius 5 cm beampipeThickness b mm sample range mk Generally the user has to define a sequence of elements with drift quadrupole line etc then select the beamline with the use command and specify beam par
28. ing the point of intersection of the particle trajectory with the boundary and hence the error in the path length in each volume This may influence the results especially in the case when EM fields are present deltaChord lengthSafety all volumes will have an additional overlap of this length thresholdCutCharged energy below which charged particles are not tracked thresholdCutPhotons energy below which photons are not tracked 6 Output Analysis During the execution the following things are recorded e energy deposition along the beamline e sampler hits If the output format is ASCII i e if BDSIM was invoked with the output ascii option then the output file output txt containing the hits will be written which has rows like hits PDGtype p GeV c x micron y micron z m x microrad y microrad 11 250 4 72907 5 86656 5 00001e 06 0 0 11 250 8 17576 4 99729 796 001 0 320334 0 126792 If ROOT output is used then the root files output O root output 1 root etc will be created with each file containing the number of events given by nperfile option The Appendix A Geometry description formats 27 file contains the energy loss histogram and a tree for every sampler in the line with self explanatory branch names Appendix A Geometry description formats The element with user defined physical geometry is defined by lt element_name gt element geometry format filename attributes for example colli element geometry gmad c
29. inimum step size element overlap safety minimum relative error acceptable in stepping maximum relative error acceptable in stepping set position error acceptable in an integration steps The following options influence the physics physicsList thresholdCutCharged thresholdCutPhotons stopTracks synchRadOn srTrackPhotons srLowX srLowGamE srMultiplicity prodCutPhotons prodCutPhotonsP prodCutPhotonsA prodCutElectrons prodCutElectronsP prodCutElectronsA prodCutPositrons prodCutPositronsP prodCutPositronsA turn nCerenkov defaultRangeCut gammaToMuFe annihiToMuFe eetoHadronsFe determines the set of physics processes used charged particle cutoff energy photon cutoff energy if set tracks are terminated after interaction with material and energy deposit recorded turn on Synchrotron Radiation process whether to track the SR photons sets lowest energy of SR to X E critical lowest energy of propagating SR photons a factor multiplying the number of synchrotron radiation photons standard overall production cuts for photons default 0 7 mm precision production cuts for photons in the precision region default 0 7 mm precision production cuts for photons in the approximation region default 1 m standard overall production cuts for electrons default 0 7 mm precision production cuts for electrons in the precision region default 0 7 mm precision production cuts for electrons in the approximation region d
30. is used to step the particle through a uniform magnetic field with no edge effects present In the case of particles with little transverse momentum s component of unit momentum vector 0 8 a thick lens matrix is used matrix assumes hard edge profile Currently the thick lens matrix represents both the edge effects and transport in the central part of the field Multiple steps through this will currenlty result in small errors in tracking due to the edge effects being applied multiple times Under development Example Chapter 3 Lattice description 12 soli solenoid 1 2 m ks 0 004 3 3 16 hkick and vkick hkick and vkick are equivalent to a rbend and an rbend rotated by 90 degrees respectively However hkick and vkick do not rotate the frame of reference e boxSize the full width of the magnet outer volume m e additionally all of the drift parameters 3 3 17 transform3d An arbitrary 3 dimensional transformation of the coordinate system is done by placing a transform3d element in the beamline Attributes e x lt x offset e y lt y offset e z z offset e phi phi Euler angle e theta theta Euler angle e psi lt psi Euler angle Example rot transform3d psi pi 2 3 3 18 element All the elements are in principle examples of a general type element which can represent an arbitrary geometric entity with arbitrary B field maps Attributes e geometry geometry descrip
31. isation gflashemax N maximum energy for gflash shower parameterisation in GeV Defa gflashemin N minimum energy for gflash shower parameterisation in GeV Defa help display this message verbose display general parameters before run verbose event display information for every event Chapter 3 Lattice description verbose step verbose event num N batch mode no graphics print geometry optics info to file type of outline format batch outline file outline_type lt fmt gt materials circular seed N seedstate lt file gt display tracking information after each step display tracking information for event number N where fmt optics survey list materials included in BDSIM by default assume circular machine turn control the seed to use for the random number generator file containing CLHEP Random seed state overrides other see To run BDSIM one first has to define the beamline geometry in a file which is then passes to BDSIM via the file command line option for example bdsim file line gmad output root batch The next section describes how to do it in more detail 3 Lattice description The beamline beam properties and physics processes are specified in the input file written in the GMAD language which is a variation of MAD X language extended to handle sophis ticated geometry and parameters relevant to radiation transport GMAD is descr
32. ite also contains information on documentation projects and installation Alternatively a development version is from the Git repository instructions are at https twiki ph rhul ac uk twiki bin view PP JAI BDsimInstall Download the tarball and extract the source code Make sure Geant4 is installed and appropriate environment variables defined Then go through the configuration procedure by running the configure script configure It will create a Makefile from template defined in Makefile in You may want to edit the Makefile manually to meet your needs if your CLHEP version is greater than 2 x put DCLHEP VERSION 9 Then start the compilation by typing make If the compilation is successful the bdsim executable should be created in BD SIM bin ARCH where BDSIM is the directory specified during configuration and ARCH is of the form OSTYPE COMPILER eg Linux g Next set up the DY LD LIBRARY PATH variable to point to the parser directory and also to the directory where libbdsim so is if building shared libraries BDSIM is invoked by the command bdsim options where the options are file filename Specify the lattice file output fmt output format rootlascii default ascii outfile file output file name Will be appended with _N where N 20 1 2 3 etc vis mac file visualization macro script default vis mac gflash N whether or not to turn on gFlash fast shower parameter
33. ith respect to the start of the object Else POSZ will be defined with respect to the center of the parent object e INHERITSTYLE Variable type VARCHAR 32 This is an optional parameter to be used with PARENTNAME If set to SUBTRACT then the instead of placing the volume within the parent volume as an inherited object it will be subtracted from the parent volume in a Boolean solid operation The default for this value is set to which sets to the usual mother daughter volume inheritance e ALIGNIN Variable type INTEGER 11 This is an optional parameter If set to 1 then the placement of components will be rotated and translated such that the incoming beamline will pass through the z axis of this object T he default is set to 0 e ALIGNOUT Variable type INTEGER 11 This is an optional parameter If set to 1 then the placement of the next beamline component will be rotated and translated such that the outgoing beamline will pass through the z axis of this object The default is set to 0 e SETSENSITIVE Variable type INTEGER 11 This is an optional parameter If set to 1 then the object will be set up to register energy depositions made within it and to also record the z position at which this deposition occurs This information will be saved in the ELoss Histogram if using ROOT output The default is set to 0 e MAGTYPE Variable type VARCHAR 32 Appendix A Geometry description formats 31 This is an optional parameter
34. magnetic field T e material the magnet material default set to Iron k1 1 Bp dB dx m Positive k1 means horizontal focusing of positively charged particles default 0 e boxSize the full width of the magnet outer volume m additionally all of the drift parameters The meaning of B and angle is the same as for rbend Example sbi sbend 1 0 5 m angle 0 01 3 3 7 quadrupole quadrupole defines a quadrupole Attributes e 1 length m default 0 e ki normal quadrupole coefficient k1 1 Bp dB dx m Positive k1 means hori zontal focusing of positively charged particles default 0 dB dx is the magnetic field gradient while Bp is the magnetic rigidity Bp T m p GeV 0 299792458 charge e e ksi skew quadrupole coefficient ks1 1 Bp dB dx m where x y is now a co ordinate system rotated by 45 degrees around s with respect to the normal one default 0 e tilt roll angle rad about the longitudinal axis clockwise e material the magnet material default set to Iron e boxSize the full width of the magnet outer volume m e additionally all of the drift parameters Example Chapter 3 Lattice description 9 qf quadrupole 1 0 5 m ki 0 5 tilt 0 01 3 3 8 sextupole sextupole defines a sextupole Attributes 1 length m default 0 k2 normal sextupole coefficient k2 1 Bp d B dx m ks2 skew sextupole coefficient k
35. mperature in K default set to 300 e P pressure atm default set to 1 e state solid liquid or gas default set to solid Example iron matdef Z 26 A 55 845 density 7 87 If the material is made up by several components first of all each of them must be specified with the atom keyword 5 In this case in src BDSDetectorConstruction cc the BDSMaterials AddMaterial name Z A density method is called which in turns src BDSMaterials cc invokes the Geant4 G4Material constructor G4Material name Z A density 6 In this case in src BDSDetectorConstruction cc the BDSMaterials AddElement name symbol Z A method is called which in turns src BDSMaterials cc invokes the Geant4 G4Element constructor G4Element name symbol Z A Chapter 3 Lattice description 14 element atom Z lt int gt A lt double gt symbol lt char gt Attributes e Z atomic number e A mass number g mol e symbol atom symbol Then the compound material can be specified in two manners 1 If the number of atoms of each component in material unit is known the following syntax can be used material matdef density lt double gt T double P lt double gt state lt char gt components lt list lt char gt gt componentsWeights lt list lt int gt gt Attributes e density density in g cm e T temperature in K default set to 300 e P pressure in atm default
36. offset from nominal z axis in y z plane ZpO Directional flag ZpO lt 0 points the particle back up the beamline TO Global time offset s 2 distrType reference a reference orbit particle which has the offsets in the global options so XO Offset of distribution centre in x m YO Offset of distribution centre in y m ZO Offset of distribution centre in z m XpO Angular offset from nominal axis in x z plane YpO Angular offset from nominal z axis in y z plane ZpO Directional flag ZpO lt 0 points the particle back up the beamline TO Global time offset s 3 distrType gauss a gaussian in x x y y energy and time with given widths sigmaX RMS of x distribution in m sigmaXp RMS of x distribution in rad sigmaY RMS of y distribution in m sigmaYp RMS of y distribution in rad sigmaE RMS of energy distribution divided by nominal beam kinetic energy sigmaT RMS of time distribution in s 4 distrType gausstwiss a gaussian bunch defined by twiss parameters 4 emittance energy and time betx B in m bety in m alfx o alfy a emitx e in m 10 see src BDSBunch cc for more details Chapter 3 Lattice description 21 e emity e in m e sigmaE RMS of energy distribution divided by nominal beam kinetic energy e sigmaT RMS of time distribution in s 5 distrType gaussmatrix a gaussian bunch defined by N N
37. olid Types Append _TORUS to the table name in order to make use of the G4Torus solid type The following table parameters are specific to the torus solid RINNER Variable type DOUBLE 10 3 This is an optional parameter If set then this value will be used to specify the inner radius of the torus tube The default value is zero Appendix A Geometry description formats 34 e ROUTER Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the outer radius of the torus tube e RSWEPT Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the swept radius of the torus It is defined as being the distance from the center of the torus ring to the center of the torus tube For this reason this value should not be set to less than ROUTER e STARTPHI Variable type DOUBLE 10 3 This is an optional parameter If set then this value will be used to specify the starting angle of the torus T he default value is zero e DELTAPHI Variable type DOUBLE 10 3 This is an optional parameter If set then this value will be used to specify the delta swept angle of the torus The default value is 2 PI A 2 1 6 Polycone Solid Types Append _POLYCONE to the table name in order to make use of the G4Polycone solid type The following table parameters are specific to the polycone solid e NZPLANES Variable type INTEGER 11 This is a required parameter This valu
38. olli geo A 1 gmad format gmad is a simple format used as G4geometry wrapper It can be used for specifying more or less simple geometries like collimators Available shapes are Box 1 xO x origin yO y_origin zO z origin x xsize y ysize z zgize phi Euler angle for rotation theta Euler angle for rotation psi Euler angle for rotation material MaterialName Cons xO x origin yO y_origin zO z origin rmini inner radius at start rmaxi outer radius at start rmin2 inner radius at end rmax2 outer radius at end z zgize material MaterialName phi Euler angle for rotation theta Euler angle for rotation psi Euler angle for rotation phiO angle for start of sector dphi angle swept by sector h Tubs 1 xO x origin yO y_origin zO z origin rmin inner radius rmax outer radius z zsize phi Euler angle for rotation theta Euler angle for rotation psi Euler angle for rotation material MaterialName Trd xO x origin yO y_origin zO z origin xi half length at wider side x2 half length at narrower side yi half length at wider side y2 half length at narrower side Z zsize phi Euler angle for rotation theta Euler angle for rotation psi Euler angle for rotation material MaterialName d Appendix A Geometry description formats 28 A file can contain several objects which will be placed sequentially into the volume A user has to make sure that there is no overlap
39. on 3 3 Physical elements page 4 A 2 1 2 Box Solid Types Append BOX to the table name in order to make use of the G4Box solid type The following table parameters are specific to the box solid LENGTHX LENGTHY LENGTHZ Variable type DOUBLE 10 3 These are required parameters There values will be used to specify the box s dimen sions A 2 1 3 Trapezoid Solid Types Append TRAP to the table name in order to make use of the G4 Trd solid type which is defined as a trapezoid with the X and Y dimensions varying along z functions The following table parameters are specific to the trapezoid solid LENGTHXPLUS Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the x extent of the box s dimensions at the surface positioned at dz LENGTHXPMINUS Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the x extent of the box s dimensions at the surface positioned at dz LENGTHYPLUS Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the y extent of the box s dimensions at the surface positioned at dz LENGTHYPMINUS Variable type DOUBLE 10 3 This is a required parameter This value will be used to specify the y extent of the box s dimensions at the surface positioned at dz LENGTHZ Variable type DOUBLE 10 3 Appendix A Geometry description formats 33 This is a required
40. p at last scatter yp Relative angle in y z yp0 yp at last scatter zp 1 sqrt xp yp zpO xp at last scatter nEvent Event number partID PDG particle identifier 3 4 4 dump Used in conjunction with option fifo lt filename gt to output the bunch distribution at a given point If the specified output file is a FIFO the distribution can be modified by an external program before being piped back in to continue tracking This is useful for including multi particle effects such as wakefields at given points in the lattice dump range dumpMarker1 option fifo tmp temp dat Output is in the standard Guineapig format with a header line stating the number of particles to be output The file to be read back should be in the same format as this 3 4 5 use use command selects the beam line for study use period 11 range q1 q2 3 4 6 print The print command will print the element list It can also print the value of an option or a variable print x 11 See Appendix D Known Issues page 37 Chapter 4 Visualization 24 4 Visualization When BDSIM is invoked in interactive mode the run is controlled by the Geant4 shell A visualization macro should be then provided A simple visualization macro is include with the distribution and is outlined below Invoke the OGLSX driver Create a scene handler and a viewer for the OGLSX driver vis open OGLIX Create an empty scene vis scene create Add detector geometry to t
41. rameters 0 0 0000 e ee 29 A 2 1 2 Box Solid Types 0 0 cece eee eee eee eee 32 A 2 1 3 Trapezoid Solid Types 0 2 cece eee eee 32 A 2 1 4 Cone Solid Types 0 c cece cece eee eee eee 33 A 2 1 5 TDorus Solid Types 0 00 e cece eee eens 33 A 2 1 6 Polycone Solid Types 00 cece eee eens 34 A 2 1 7 Elliptical Cone Solid Types 0005 35 A 2 2 Creating a geometry list 00 0 0 cece eee eee eee 35 A 2 3 Defining a Mokka element in the GMAD file 36 A3 pdm nolesseneduau torisida in ena A agua ne npe a ds 36 Appendix B Field description formats 36 Appendix C Bunch description formats 36 Appendix D Known Issues 37 References 0 ccc cece ren 37 ii Chapter 2 Obtaining Installing and Running 1 BDSIM v0 6 User s Manual This file is updated automatically from manual texi last updated on 22 May 2015 1 About BDSIM BDSIM is a Geant4 1 extension toolkit for simulation of particle transport in accelerator beamlines It provides a collection of classes representing typical accelerator components a collection of physics processes for fast tracking procedures of on the fly geometry construction and interfacing to ROOT analysis 2 2 Obtaining Installing and Running BDSIM can be downloaded from https twiki ph rhul ac uk twiki bin view PP JAI BdSim This s
42. s2 1 Bp d B dx m where x y is now a co ordinate system rotated by 30 degrees around s with respect to the normal one default 0 tilt roll angle rad about the longitudinal axis clockwise material the magnet material default set to Iron boxSize the full width of the magnet outer volume m additionally all of the drift parameters Example sf sextupole 1 0 5 m k2 0 5 tilt 0 01 3 3 9 octupole octupole defines an octupole Attributes 1 length m default 0 k3 normal octupole coefficient k3 1 Bp d B daz m Positive k3 means hori zontal focusing of positively charged particles default 0 ks3 skew octupole coefficient ks3 1 Bp d B da m t where x y is now a co ordinate system rotated by 30 degrees around s with respect to the normal one default 0 tilt roll angle rad about the longitudinal axis clockwise material the magnet material default set to Iron additionally all of the drift parameters Example of octupole 1 0 5 m k3 0 5 tilt 0 01 3 3 10 multipole multipole defines a multipole Attributes 1 length m default 0 knl normal multipole knl n 1 Bp d B dz m Chapter 3 Lattice description 10 e ksl skew multipole ksl n 1 Bp d B dx m where x y is now a coor dinate system rotated by 30 degrees around s with respect to the normal one default 0 e tilt roll angle ra
43. set to 1 e state solid liquid or gas default set to solid e components list of symbols for material components e componentsWeights number of atoms of each component in material unit in order Example niobium atom symbol Nb z 41 a 92 906 titanium atom symbol Ti z 22 a 47 867 NbTi matdef density 5 6 temperature 4 0 Nb Ti 1 1 2 On the other hand if the mass fraction of each component is known the following syntax can be used material matdef density double T lt double gt P lt double gt state lt char gt components lt list lt char gt gt componentsFractions lt list lt double gt gt Attributes T n this case in src BDSDetectorConstruction cc the BDSMaterials AddMaterial name density state temp pressure list lt char gt itsComponents list lt G4int gt itsComponentsWeights method is called which in turns src BDSMaterials cc invokes the Geant4 G4Material constructor G4Material name density G4int itsComponents size state temp pressure Then each component is added with a call to the G4Material AddElement G4string G4int method In this case in src BDSDetectorConstruction cc the BDSMaterials AddMaterial name density state temp pressure list char itsComponents list G4double itsComponentsFractions method is called which in turns src BDSMaterials cc invokes the Geant4 G4Material constructor G4Material nam
44. t userdocuments shtml 2 Root User s Guide http root cern ch drupal content users guide 3 MAD X User s Guide http madx web cern ch madx madX doc usrguide uguide html 4 for example Basic course on Accelerator optics by Schmuesser Rossbach CERN Accelerator school 5 A Ribon et al Status of GEANT4 hadronic physics for the simulation of LHC experiments at the start of LHC physics program CERN LCGAPP 2010 02 July 20 2010
45. ter radius of a quadrupole use the outR parameter in the same way as for other elements 3 3 24 Element number When several elements with the same name are present in the beamline they can be accessed by their number in the sequence In the next example the sampler is put before the second drift bl line d d d See Appendix D Known Issues page 37 Chapter 3 Lattice description 16 sample range d 2 3 3 25 Element attributes Element attributes such as length multipole coefficients etc can be accessed by putting square brackets after the element name e g x d 1 3 3 26 Editing apertures Apertures can be set after an element has already been defined by writing the element name followed by a semicolon followed by the attributes For example if quadrupole qf has already been defined then its aperture can be set to 4 mm using qf aper 4 mm 3 3 27 Material table There is a set of predefined materials for use in elements such as collimators e g Air LiquidHelium Aluminium NbTi BeamGasPlugMat Niobium Beryllium Silicon CarbonMonoxide SmCo CarbonSteel Soil Concrete Titanium Copper TitaniumAlloy Graphite Tungsten Invar Vacuum Iron Vanadium Laser Vac Water Lead WeightIron LeadTungstate Currently Air CarbonMonoxide and Vacuum
46. tion e bmap bmap description e outR limits external extent component box size default set to tunnelRadius 2 Descriptions are of the form format filename where filename is the path to the file with the geometry description and format defines the geometry description format The possible formats are given in Appendix A Geometry page 2T Example qq element geometry mokka qq sql bmap mokka qq bmap Chapter 3 Lattice description 13 3 3 19 line Elements are grouped into sequences by the line command line name line element 1 element 2 where element_n can be any element or another line Lines can also be reversed using line name line line 2 or within another line by line line 1 line 2 Re versing a line also reverses all nested lines within Example A sequence of FODO cells can be defines as qf quadrupole 1 0 5 k1 0 1 qd quadrupole 1 0 5 k 0 1 d drift 1 0 5 fodo line qf d qd d section line fodo fodo fodo beamline line section section section 3 3 20 matdef To define a material the matdef keyword must be used If the material is composed by a single element it can be defined using the following syntax material matdef Z lt int gt A lt double gt density lt double gt T lt double gt P lt double gt state lt char gt Attributes e Z atomic number e A mass number g mol e density density in g cm e T te
47. uction processes with bi ased muon cross sections hadron QGSP BERT muon tracking with high precision neutron Chapter 6 Output Analysis 26 hadronic FTFP BERT em standard plus hadron physics using the Fritiof model fol lowed by Reggion cascade and Precompound and evaporation models for the nucleus de excitation FTFP model and the Bertini cascade model BERT hadronic_FTFP_BERT_ hadronic_FTFP_BERT plus muon production processes with muon biased muon cross sections By default the standard physics List is used 5 2 Transportation The transportation follows the scheme the step length is selected which is defined either by the distance of the particle to the boundary of the logical volume it is currently in which could be e g field boundary material boundary or boundary between two adjacent elements or by the mean free path of the activated processes Then the particle is pushed to the new position and secondaries are generated if necessary Each volume has an associated transportation algorithm For an on energy particle travelling close to the optical axis of a quadrupole dipole or a drift standard matrix transportation algorithms are used 4 For multipoles of higher orders and for off axis energy particles Runge Kutta methods are used 5 3 Tracking accuracy The following options influence the tracking accuracy chordStepMinimum minimum chord length for the step deltaIntersection determines the precision of locat
48. urad e guineapig slac E GeV x rad y rad zImum x nm y nm e guineapig pairs E GeV x rad y rad z rad x nm y nm z nm here a particle with E 0 is assumed to be an electron and with E 0 a positron e cain A custom distribution file format can be specified in the form distrType fieldi uniti fieldi uniti The allowed values for fields units are For instance 1 see src BDSBunch cc for more details References 37 beam particle e energy ener GeV distrType pt 1 E GeV xp rad yp rad z mum x nm y nm distrFile bunches beam dat Appendix D Known Issues Samplers attached to multiple instances of the same element incorrectly register hits only from the first instance in all such samplers For example drifti drift 1 1 m marki marker linei line marki drifti marki drift1 sample range mark1 1 sample range mark1 2 will incorrectly record hits at mark1 1 in the sampler attached to mark1 2 To avoid this samplers should be attached to uniquely named elements There is a known issue with the z parameter output to samplers As particle data is output at the z location of the sampler when the global position is transformed from global to relative coordinates z is identically zero For a description of a particle s longitudinal position in the bunch please use the parameter s instead References 1 Geant4 User s Guide http geant4 cern ch suppor
49. would be symbols can be used for commenting out an entire line directory boxes sql directory cones sql Appendix C Bunch description formats 36 A 2 3 Defining a Mokka element in the GMAD file The Mokka element can be defined by the following command element name element geometry format filename attributes where format must be set to mokka and filename must point to a file that contains a list of files that have the geometry descriptions for example collimator element geometry mokka coll_geomlist sql A 3 gdml GDML is XML schema for detector description GDML will be supported as an external format starting from next release Appendix B Field description formats The element with user defined magnetic field map is defined by the command element name element bmap format filename attributes for example colli element bmap XY colli bmap Supported formats are mokka and XY In the latter case a text files must be speci fied where each rows must have the following format x y Bx By Bz Appendix C Bunch description formats For compatibility with other simulation codes following bunch formats can be read For example to use the file distr dat as input the beam definition should look like beam particle e distrType guineapig bunch distrFile distr dat The formats currently supported are listed below e guineapig bunch E GeV x mum y mum z mum x murad y m
50. ypes are e marker e drift e rbend e sbend e quadrupole e sextupole e octupole e multipole e vkick e hkick e rf e rcol e ecol e solenoid e laser e transform3d e element All elements except marker element ecol transform3d and rcol are modelled with a beampipe and an outer surrounding volume The beampipe form dimensions and materials are controlled by the following parameters Chapter 3 Lattice description 5 e beampipeRadius e beampipeThickness e beampipeMaterial e apertureType e aperl e aper2 e aper3 e aper4 e vacuumMaterial These parameters can be set with the option command as the default parameters and also on a per element basis that overrides the defaults for that specific element Up to four parameters can be used to specify the aperture shape aperi aper2 aper3 aper4 These are used differently for each aperture model and match the MADX aperture definitions The required parameters and their meaning are given in the following table Aperture Number of aperl aper2 aper3 aper4 Type parameters circular 1 beam pipe NA NA NA radius rectangular 2 x half width y half width NA NA ellipse 2 x semi axis y semi axis NA NA Ihcscreensimple 3 x half width y half width radius of NA of rectangle of rectangle circle Ihcscreen 3 x half width y half width radius of NA of rectangle of rectangle circle rectellipse 4 x half width y half width x semi axis y semi axis of rectangle of rectangl
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