Drift Chamber Control and Readout System Technical Description
Contents
1. ASD ECL CNV ASD ECL CNV 767 Figure 1 Channel and Geometry 23 24 APPENDIX 2 Readout Data Format VME readout data format 1 x time line QUEUE HOUR MINUTE SECOND 1 x header line NUM TYP 0110 R IVC EVENT HIT NUMBER A event hit data lines 0 P F CHN 010 TIME DATA R 5 R Ld Ll header line NUM module number number 12 TDC_1176 2 TDC V767 0 relative time measurement 1 absolute time measurement only V767 IVC _ interrupt vector data line O R 0 data channel 1 reference channel only TDC_V767 CHN channel number P S 0 P common stop 1 S common start F R 0 F falling edge 1 rising edge Figure A 2 TDC Readout Data Format 3 ELECTRONICS 3 Electronics PR NR BRR Hm DIS DPL GDU IOR ENC TDC AEC COC DIB Module Typ VME CPU HP 9000 High Voltage Module 8 Channel Discriminator Dual Programmable Logic Unit 8 Channel Gate and Delay Generator 16 Channel Programmable I O Register 8 Channel NIM ECL ECL NIM Translator 128 Channel General Purpose Multihit TDC ASD 8 ECL Translator Coincidence Unit PMT Control Supply ASD 8 Distribution Board Typ 7432. 2 IPC Schemes HP RT IPC STA STT STA STP STA IRQ CLIENT SERVER HANDLER CLIENT SERVER 27001 d QUESET DEVCPY SIG GSM GSM DEVCPY DEVCPY DEVCPY 1 SIGUSRI lt 2 2 L so gt an lt warr gt E DEVCPY DEVCPY 2 SIGUSR2 WAIT si gt Y Figure 1 HP RT IPC 2 IPC SCHEMES 29 LINUX IPC STA_STT STA_STP STA_IRQ TO_CHST lt em gt QUESET GSM 1 TO_STTH 2 TO_CHST SIG DEVCPY SIGUSR2 hereticis Su rue ro o SIG SIGUSR2 SIG gt um Figure B 2 LINUX IPC STA_STT LINUX IPC DATA HANDLER STA_STP 12700 A QUESET e DEVCPY DEVCPY DEVCPY SIGUSRI SIG gt lt WAIT gt re SIG SIGIO DEVCPY RDO gt RDO Figure B 3 Data Server IPC 30 LINUX IPC EVENT DISPLAY PARENT GSM START CHILD DEVCPY WAIT A DISPLAY SIGUSRI SIGUSR2 STOP GSM APPENDIX B VME DATA HANDLER GSM DEVCPY lt PID Inr ees Figure B 4 Event Display IPC Appendix Drift Cham
3. 10 CHAPTER 2 DRIFT CHAMBER HARDWARE The high voltage for all PMTs is derived from a control voltage and adjustable with potentiometers in the range from 0 to 1 V Based on the coincidence out put signal COO the state of a software controlled veto SV T and the state of a hardware switched veto HV T all other signal lines are set as depicted below ENC start stop 7 VTO 6 SVT read out cycle 5 HVT z 4 COO 3 DLB variable delay 2 DLA Y variable delay A 1 COM 0 INT min delay 320 ns 160 ns fixed DLA and DLB max delay 1240 ns Figure 2 7 VME Trigger Diagram Core of the trigger circuit is a dual programmable logic unit DPL CAEN V495 A 3 During the trigger initialization the internal lookup table contents of the DPL must be programmed Furthermore the variable delays of the gate and delay unit GDU must be set The resulting total delay is the time window during hits the channel input pulses can be converted into digital time values The total delay is adjustable between 320ns and 1240ns and set to 1000ns This value has to be set also as equivalent time window and offset parameter in the TDC configuration 2 4 READOUT SYSTEM 11 Additional the output lines DLA channel 0x02 and channel 0x03 are connected with two TDC reference input channels 0x0
4. raw data output file vme dta raw x x parameter description default value HP RT LINUX VME_ELOG _ event log enable disable DISABLE x x VME_EDTA event log file table vme_evn x x VMESLOG state log enable disable DISABLE x x VME_SDTA state log file table vme sta x x VME LOGD log output directory Jetc VME log x x PARD module parameter directory etc VME par x x VME PRGD program directory etc VME prg x x VME RAWD raw data directory Jetc VME raw x x must be set with command parameters program parameters not used in the actual version must be adapted system specific Program Parameters A client call at terminal console without any additional program parameters lists all available parameters as an usage information Only the parameters without a beginning character are user parameters C 3 1 File Table Copy vme c a lt file gt lt database table gt w lt file gt lt database table gt appends the content of a file or database table to an already existing file or table or creates a new file or table and copies the content At HP RT side only the file copy functionality is available call without the second parameter w or wrt deletes the file or table given by a or app To select a database and a table the construct database table gt has to be set All other necessary values are initalized with settings delivered in
5. vme vme_h0m to shutdown Optimal values for the high voltage are HVM_VLS 2200 2400 switch off the HV this parameter must be 0 36 APPENDIX C DRIFT CHAMBER USERS MANUAL C 4 Event Display The event display can run different modes online and offline and allows sim ply to switch between both modes At program start and each time an offline simulation is finished the program returns into the default online mode The 2 0 based user interface is typical a symbolic link to the server pro gram evn s so it is possible to create links with different names and locations in the file system The default location of the user interface is usr local bin evn c start the event display simply type in evn c s The program can be closed with EXIT or Alt F4 Independent from the run mode it is possible to stop and continue the event presentation An offline simulation starts if a raw data file is choosen in the file selection win dow as shown below During an offline processing the simulation can additional finished with a right mouse button click gt QUIT Furthermore two counters are available Between the default relative and the absolute counter can be toggled with the middle mouse button The use of the right mouse button resets the relative counter C 4 EVENT DISPLAY New Folder DeleteFile RenameFile mnt eeh epler VME dev Y Folders 4 vme c gdu cfg of vme c hvm cfg vme
6. ODBC Application Interface 13 13 14 16 19 20 20 20 21 23 23 24 25 27 27 28 31 31 32 32 33 34 36 39 1 Introduction This documentation is focused on technical aspects hardware and software of drift chamber developed and build up in cooperation between DESY Zeuthen and the physics department of the Humboldt University Berlin First calibrations were done in 2005 with a meanwhile changed release and publicated in 01 It is now possible to read out all 72 drift tube channels because the formerly used four 16 channel LeCroy TDCs 1176 are replaced against one 128 channel TDC CAEN V767 Furthermore an adapted VME trigger system is now in use Important software parts are rewritten and additional features integrated Details are documented in the DRC Users Manual attached to this documenta tion 4 CHAPTER 1 INTRODUCTION Figure 1 1 Drift Chamber Chapter 2 Drift Chamber Hardware 2 1 Gas System All 72 drift tubes are coupled in series with a gas bottle equipped with gas flow and pressure regulators The chamber gas is a mixture of 80 Ar gain part and 20 quench part The gas pressure must be high enough to compensate the small gas leakage and is adjustable with a flow meter regulator The indication of a proper gas pressure and consumption is a bubble frequency around 1Hz at the oil filled gas flow controller gas pressure of around 1bar corresponds to app
7. VHQ 205L V258 V495 V486 V513 V538 A V767 AEC COC DIB 25 Manufacturer HP ISEG CAEN CAEN CAEN CAEN CAEN CAEN DESY Z EW HU DESY Z EW HU EW 26 APPENDIX Appendix B B 1 Module Parameters Each module configuration contains common and special parameters module addresses and the modules address modifiers are necessary for each mod ule The interrupt level and vector must be set for interrupt generator modules IOR For readout modules ADCs TDCs the interrupt vector value defines the run queue number shared with an interrupt generator module An interrupt controlled readout is only possible if exactly one interrupt generator module is defined per queue Optional one or more maximum 7 readout mod ules can be attached to a queue The initialization order is free The channel number is only valid for channel providing modules run mode is set module specific and defineded in the structure 156 vme_m h common parameter description lt MOD gt _ADR VME address lt MOD gt _ADM VME address modifier lt MOD gt INT VME interrupt level lt MOD gt IVC VME interrupt vector lt MOD gt _CHN module channel number lt MOD gt _RMD module run mode All other parameters are module attached special parameters The special pa rameter definitions contains the structure 156 vme_m h the special pa rameter settings the structure spc lst vme_m h 27 28
8. c ior new vme dta raw vme dta raw counter E Selection mnt eeh epler VME dev SIMU vme dta 2300 raw Figure C 1 Offline File Selector Figure C 2 Event Display 38 APPENDIX C DRIFT CHAMBER USERS MANUAL Appendix D ODBC Application Interface The ODBC open database connectivity API library functions dopen dclose dgets dputs and demove are entry point functions to create to transfer data to and from and to delete tables in a SQL database system with the same call conventions and return values as defined for the ANSI C stdio functions fopen fclose fgets fputs and remove Additional defined dopen C style format parameters can be used and listed at end Requirements for installation and database access L My ODBC and IODBC libraries and includes must be available all necessary configurations and permissions to connect the database system to create or delete tables and to insert data into a table Entry Point Functions and Format Parameters 39 40 APPENDIX D ODBC APPLICATION INTERFACE FILE dopen const char db tb name const char format db tb name a string construct database table the double colon is the delimiter to separate database and table format a format string similar used for the stdio function fopen p or r open an existing table for read operations w w create a no
9. inter process communication system IPC is integrated It is controlled by the signals SIGUSR1 SIGUSR2 SIGTERM and SIGIO The general principle is shown below lt GM GSM get shared memory attach shared memory DEVCPY DEVCPY DEVCPY copy into from shared memory DSM DSM DSM detach shared memory sw Le S W kill sigwait SIGUSR2 FCC FCC gt optional function call Figure 3 2 IPC sheme transfer data between process and process B a shared memory device is used This must requested before and released later it depends on the spe cific program flow The initial process defined as client attaches this shared memory device and copies data from the process memory into the shared mem ory The peer process defined as server is responsible to initialize the shared memory at least with a process identification number PID typical the servers own PID If the client needs a server response then also the clients PID must be copied into the shared memory Because both processes can act as client or as server a client and a server receiver signal should be defined If the client or the server has finished the copy procedure the initial process can now send a signal to the peer The suspended peer process can now continue and attach the shared memory copy the data into its own process memory and finally detach the shared memory The different IPC schemes a
10. rebooted the trigger initialization is necessary Start Queue readout queue includes the initialization of the CAEN V767 and the IOR CAEN V513 Optional it is possible to change the raw data output file name vme c s vme c tdc cfg or vme c s vme vme_tdc vme c s vme c ior cfg or vme c s vme vme ior lt b vme_dtb raw gt As response to a run queue start the state is printed at the clients console vme c irq 0 run mod 0 1 ivc 0 0x00 vme c irq 0 run mod 0 2 ivc 0 0x00 PROGRAM PARAMETERS 35 Stop Queue running readout queue can be stopped with vme c x queue or vme c x all or suspended with vme c 4 lt msa_adr gt and reinitialized with an appropriate start command lt msa_adr gt parameter is the most significant address of the or and can be listed with a type query call vme c t all If one or all queues are stopped the state is printed at the console vme c irq 0 stp State Query run state query with vme c q queue or q all prints the same state information for one or all queues as shown above Set and Reset the High Voltage The HV module configuration to switch on the anode high voltage can be de livered with following start command calls vme c s vme c hvm cfg vme c s vme vme hvm to set shutdown or change the high voltage a different configuration must be used vme c s vme_0_hvm cfg vme c s
11. short signal puls at the output available The three scintillator blocks are mounted above the top drift tube section and below the lower two sections PMT output signals discriminated and width shaped with a discriminator DIS CAEN 258 A 3 feed now the inputs of the coincidence unit COC A 3 With DIP switches available at the front cover of this module the input chan nels of the COC circuit can be activated right position or deactivated The 2 3 TRIGGER SYSTEM 9 resulting width shaped coincidence output signal COO is the trigger input for the following shown circuit DPL GDU ENC IOR COC DIS WDT 69 150 70 e Qe O O O 5 DLB DLA 7 so od toi IN our ue bog 1 5 TST cdd 121 SYNO 7O vroO o bog STB gt O ID 5 1 STB O I en OU 70 COO HVT 2 o D WDT e IN OUT OUT OUT OUT OUT gt M 0 N A gt N 0 La C x xus WDT eae OcomO oQur O Figure 2 6 Trigger Circuit
12. Drift Chamber Control and Readout System Technical Description Experimental Particle Physics Department of Physics Humboldt University Berlin Epler August 2006 Contents 1 Introduction 2 Drift Chamber Hardware 2 1 Gas culos EU dubbed DESERTAM s 2 2 Drift Tubes and Frontend Electronics 2 3 Trigger System an tue IR Ree ew 2 4 TDC Readout System 3 Drift Chamber Software Overview 55 A NU PEU Sed 3 2 HP RT device driver 3 3 Program xa lo oe ee PE X xen 34 library 3 5 ODBlibrary odblib 3 6 State and Event Log Interface 3 7 Event Display you Robe eene e ex ded 4 Conclusion and Outlook Channel and Geometry A 2 Readout Data Format 3 Electronics 1 Module Parameters B 2 IPC Schemes C Drift Chamber Users Manual Common Remarks o 22222221294 xxx C 2 Global Parameters Program Parameters C 3 L File Table Copy os ect Remb od C 3 2 Raw Data Transfer 3 3 Readout Control p e c ecs og omg CA Event Display ec nando yo ara a D
13. F and Ox1F A total delay DLT fine adjustment is therefore in following sequence possible 1 compute DLB T ch 0x1F T ch 0x0F noise measurment 2 set DLB so that DLT 2 DLB 3 set DLA DLB DLA and DLB must be set as equivalent parameters in the GDU configuration The programmable GDU multiplexer output can be used to check the settings with an oscilloscope 2 4 Readout System The TDC readout is interrupt controlled by a VME single board computer and attached to interrupt level 1 standard system has 6 levels Additional at each level it is possible to select different interrupt capable mod ules by an one byte wide interrupt vector used interrupt generator module is an input output register CAEN V513 A 3 All 16 channels of the IOR can be set as input or output In this case channel 0 is programmed as input all other channels are outputs As depicted in figure 2 6 Trigger Circuit channel 0 is connected to the in terrupt line INT Simultaneous to the TDC conversion start the IOR generates an interrupt During the following read out cycle the interrupt is deactivated the software controlled veto line SVT is activated and the software signal SIGIO is send to a suspended readout handler process these command calls are processed inside device driver module If the handler has received this signal the process can now continue and leave the sigwait state Following all
14. This board contains also a central power supply for all ASD 8 modules The positive and negative power voltages are adjustable with front cover mounted fine tune potentiometers The power cables are small shielded flat cables separated from the signal cables 8 CHAPTER 2 DRIFT CHAMBER HARDWARE 2 3 Trigger System The trigger and readout electronics is placed in a VME versa module euro card crate and controlled by a single board computer HP 9000 743 in the left slot of the crate as shown below Figure 2 5 based electronics The VME modules and also the single board computer are connecteded to the crates data backplane The CPU processes a UNIX system with real time kernel extensions and a number of special VME read and write functions Each time a myon u or as result of a particle decay in the higher earth athmosphere gt pion decay crosses the drift chamber scintillator blocks an ini tial trigger is generated quants emitted by the build in organic scintillator plates in UV frequency range and transformed by wavelength shifters pass the internal coupled ligth fibers and hit the cathode of a PMT photo multiplier tube Hamamatsu H5783 Based on the light electrical effect the cathode emits electrons Acceler ated by an electrical field between the cathode a number of dynodes and the anode additional amplified by an avalanche process the resulting electron flow is as a
15. VME_ODBC and VME ODSN PROGRAM PARAMETERS 33 C 3 2 Raw Data Transfer vme c y source file b lt destination_file gt transfers the content of the source file from host to host B given by VME CHST 34 APPENDIX C DRIFT CHAMBER USERS MANUAL C 3 3 Readout Control All necessary steps to initialize and start a run queue can be done with only one command call several module specific calls or module combined calls The module initialization order is fixed by an array index defined in vme_lib as listed below array index DMC ADC TDC DIS GDU IOR HVM ADC 0 TDC 0 01500 0900 0 HVMYJ0 10151 IOR 1 DMC ADC 7 DIS GDU 7 IOR 7 The initialization order starts at index 0 and ends with 7 Only the allocated and initialized memory blocks beginning from block 0 are used for the finally module initialization If VME module initialization is finished all allocated blocks are now released In the following example a module combined initialization is shown Trigger Initialization To initialize the trigger it is necessary to set the variable delay length DLA and of a gate and delay unit CAEN V486 and to program the lookup tables of a logical unit CAEN V495 parameter configuration file or table is delivered with vme c s vme_c_trg cfg or vme c s vme vme_trg Each time the VME CPU has booted or
16. ber Users Manual C 1 Common Remarks The main program is processed in several run modes depend on call parame ters on two operation systems HP RT and LINUX user interface the client is typical a symbolic link to the main program vme s It is possible to create links with different names and locations in the file system for example in HOME bin The default location of the main program is usr local sbin vme s the default location of the user interface is usr local bin vme c On both operation systems the same program parameter set is available except the database functionality at HP RT side C 2 Global Parameters Only the parameter set read in by the client the user interface is valid and transfered to the clients peer servers The default parameter configuration file is etc VME vme cfg but also a user defined configuration can be delivered with the program call vme c g par glb cfg lt DB par glb gt s par dta cfg lt DB par_dta gt 31 32 APPENDIX C DRIFT CHAMBER USERS MANUAL parameter description default value HP RT LINUX VME ODBC ODBC initialization file etc odbc ini x VME_ODSN ODBC data source name vme x VME ALLW hosts allow file etc hosts allow x x VME CHST command execution host localhost x X VME WHST WWW server localhost x x VME_WPRT WWW port 80 VME_DHST data receiver host localhost x X VME PDTA module parameter data NULL x x
17. can now as a signal amplified shaped and discriminated with the frontend module ASD 8 Each ASD 8 module includes two 8 channel chips in summary 16 channels per board Depicted in fig A 1 Channel Map and Geometry the left 12 anodes and the rigth 12 are coupled with one board respectivly 2 2 DRIFT TUBES AND FRONTEND ELECTRONICS CLEEELELELELETIT HHE ARA AAA DARAN SOCIA j i Figure 2 4 ASD 8 boards The ASD 8 outputs are connected over shielded flat signal cables with level converter modules ASD 8 ECL Translator A 3 placed in a VME crate The level converter outputs are standard ECL emitter coupled logic signals and directly connected with TDC input channels Since the hardware upgrade end of 2005 CAEN V767 is now in use The TDC time resolution is 0 8ns LSB equivalence Because only a common stop emulation run mode is provided the delayed trigger common stop line is additional connected as reference channel to a TDC input To allow a delay fine calibration in this case a second reference channels is also connected The sum of both delays GDU output channel 0x03 is the total hit conversion time window To minimize the signal noise it is necessary to set appropriate thresholds for each ASD 8 module This is now possible separatly with fine tune potentiometers for all 6 ASD 8 boards The potentiometers are avalaible at the front cover of the distribution board DIB A 3
18. d Control System Two libraries are linked with the main program Both libraries odb lib gt libiodb a libiodb so and vme lib gt libivme a libivme so provide shared used and operation system specific parts The main program vme s can process different modes client from a terminal console client in server mode command server and readout or data handler 13 14 CHAPTER 3 DRIFT CHAMBER SOFTWARE server The several server modes are invoked by the x inetd super server dae mon depend on call parameters set in the x inetd configuration for different ports A symbolic link to the main program allows to start the client with different names from different locations inside the file system The server processes perform a connection check for calling hosts which must explicitly be listed as allowed hosts except localhost Furthermore the daemon server processes change the group and user identification equal to the clients ID So a readout queue run state query is allowed but it is not possible to stop this queue if the UID and GID differs Additional to the program parameters there are a number of global parameters available Only the global parameters read in by the client are valid for all peer servers detailed description of all available global and program parameters is given in the drift chambers user manual C In some cases it is possible and necessary to overwrite global with program pa rameters Optional the default gl
19. ier gt lt specifier gt dgets reads out only the matching parts dgets returns the pointer to buf as long as the last row isn t reached or else NULL int dputs char buf FILE dfp buf a pointer to a delivered buffer dfp a FILE pointer returned by a dopen call before dputs inserts the column type converted value s from the buffer into a table missing values are written as null equivalents dputs returns 0 at success or else EOF int demove const char db_tb_name db_tb_name string construct database table demove connects the database system and navigates into the database removes the table if the table exist and the necessary grants are present disconnects from the database system and returns 0 at success or else format parameter SQL type s varchar SQS MAX SQS_MAX 254 76 n s varchar lt n gt n 1 254 int int unsigned double date 96t time 42 APPENDIX D ODBC APPLICATION INTERFACE Bibliography 1 Siddeequah Azmi Calibration of Cosmic Ray Tracker HU Dep of Physics June 2005 2 The ATLAS Myon Collaboration ATLAS muon spectrometer technical de sign report CERN LHCC 117 150 May 1997 3 HERA B Outer Tracker Group The Front End Electronics of the HERA B Outer Tracker Detector DESY April 2002 4 H U Kirst H Kolanoski V Suvorov F Tonisch S Vassiliev M Walter Test Results of a Multi Laye
20. n existing table with one column type varchar to open and clear an already existing table for write operatic a a4 to open an already existing table or to create it new for appe An optional index parameter i is defined to create more then only one column and to define different column types dopen lt database gt lt table gt a i int index 96i string index 9620s hex index 96x navigates into the database and creates a table with following index specifiers and column formats int_index int string index varchar 20 hex_index int unsigned If an index specifier is not set or left free an internal format converter creates this as followed IDX for a table with only one column IDX_0 IDX_1 for tables with more then only one column 41 int dclose FILE dfp dfp a FILE pointer returned by a dopen call before The function dclose disconnects from a database system if dfp is a valid pointer the return value of a successful dopen call and frees the internal memory allocated by dopen before dclose returns always 0 char dgets char buf int size FILE dfp buf a pointer to a delivered buffer Size the buffer size dfp a FILE pointer returned by a dopen call before dgets reads one row from a table copies the ASCII converted and space separeted values into the buffer and increments an internal read pointer If a compare string was set before with strcpy ofp sql cps lt index_specif
21. obal parameter file can be replaced by a user defined file or database table To decouple the main program from specific access functionalities the library odb lib defines functions to allow the exchangeable use of sockets files and database tables Underlying parts of the inter process communication IPC between the data handler service on LINUX side and a state and event log in terface is also defined here Furthermore a line parser and a line writer allows to read and write configura tion and parameter strings from or into streams files or database tables second library vme lib provides the initialization and readout functions for the VME modules and parts of the IPC system A more detailed library description follows in chapter 3 4 and 3 5 3 2 HP RT device driver To provide the asynchronous interrupt service a device driver is linked with the HP RT kernel In summary 8 different handler processes can run in paral lel Therefore each readout handler has an own interrupt service During the readout process initialization the appropriate driver is initialized If the inter rupt level between driver and VME module configuration matches the interrupt vector is delivered to the driver gt vme init int vme lib Later the handlers process ID the VME interrupt module type the modules VME address the address modifier byte and a veto line SVT corresponding output value is deliv ered by several ioctl calls gt vme_set_drv
22. ode TDC_RTP AQUISITION TDC run type TDC_MTP RELATIVE TDC measurment type TDC_EDG RISE TDC hit edge TDC_WIN 40 TDC hit window TDC_OFW 40 TDC hit window offset TDC_CMD CMD_00 TDC command marker CMD_00 0x1600 0 TDC command If the configuration line parsing is finished a hardware type check at the given VME address follows If this check is successful then the VME module can be initialized Depend on the initialzation return value the necessary module parameters for the handler control and readout are copied into a global memory buffer provided by the main program If the module initialization is finished all allocated memory blocks can now released 20 CHAPTER 3 DRIFT CHAMBER SOFTWARE Additional the library provides an entry point function to scan the type and the serial number of all or only one module attached to a address gt vme sen type Another entry point function is used to read out all modules listed in a handlers run queue ADCs TDCs gt vme mod rdo Already explained in chapter 3 2 the library exports also the necessary functions for the interrupt service initialization and some underlying parts of the IPC system gt devcpy 3 5 library odb_lib This library containes a line parser a line writer a number of converter func tions a state and event log interface and an open database connectivity ODBC application interface The ODBC interface and additional the socket access functions
23. r Board Based on the ASD 8B Chip DESY August 1995 5 W Richard Stevens UNIX Network Programming Prentice Hall PTR 1998 43
24. rdware and software release it is now possible to do the next step and make it available as a lab experiment for students Before this can be done it is necessary to determine the DRC working point again the operation conditions at which the chamber provides the highest detection probability optimal anode high voltage versus optimal ASD 8 thresholds Because the TDC type was changed also a new to calibration is necessary new state and event log interface allows to use a stable and independent working event display the extended IPC system to integrate the data aquisition control into a more userfriendly environment At this place my thank to all who participated in building up and testing the DRC 21 22 CHAPTER 4 CONCLUSION AND OUTLOOK Channel and Geometry ASDS ASDS CX aX xxx HV BACKPLANE _ CaX ex X XX L 2 C 6060000600 0 1 2 SEO EZ 2660660066 L 1 B 00000000 red PT a 450 drift chamber channel map TL TR TDC_CHN L 0x20 like D 0x10 0 40 0 50 0 40 DRT I ML MR 0x20 0x30 BL BR B 0 00 0 10 0 20 0x00
25. re depicted in appendix B 2 The actual run state 3 3 17 and other queue informations exist a in each queue owned shared mem ory Handler and command servers are invoked from the x inetd super server daemon Each handler process is responsible for requesting and freeing the shared memory resources 18 CHAPTER 3 DRIFT CHAMBER SOFTWARE allow a flexible way to read and write configuration data and state informa tions from or into sockets files or database tables the library odb lib provides this functions This allows to handle sockets and database tables similar to files A short description follows in chapter 3 5 minimize the dead time of the HP RT readout cycle it is possible to write the data into a TCP IP stream instead of a file This stream is opened if the VME system has an attached data handler host at run queue start set by the VME_DHST parameter and closed at run queue stop mechanism called signal driven IO 05 allows the receiver host to read data from the stream buffer and to write this data into a new created or already existing output file Additional the last n data events can be made available for an event display can be set with the global parameter VME_ELOG The interface for state and event logging is explained in chapter 3 6 On VME side the module control and readout functions are defined in a separate library vme lib This library exports the necessary ent
26. roximatly 25 30 units at the flow meter scale It is important to fill the drift tubes at least one hour before the anode high voltage is turned on If the chamber was not used for longer time the gas system should switched on around 2 3 hours before the measurment starts Figure 2 1 Gas Regulator and Flow Meter Figure 2 2 Gas Flow Controller 6 CHAPTER 2 DRIFT CHAMBER HARDWARE 2 2 Drift Tubes and Frontend Electronics The drift tubes and also the frontend electronics were designed for high energy experiments at CERN ATLAS and DESY HERA B Details are publicated in several papers only a selection is 02 03 04 Each of the three drift chamber sections includes 24 drift tubes mechanical mounted in three layers with 8 tubes per layer in a honeycomb construction The exact geometrical dimensions are depicted in fig A 1 Channel Map and Geometry Electrical each section is conducted to a HV plate shown below Figure 2 3 HV plate The HV plates are the distributors for the positive voltage of around 2200 2400V Each inner thin tube wire the anode is connected to this plate The tube wall is grounded so that an electrical field as function of the radial distance from the anode wire is build up between the anode surface a and the inner surface of the wall b after the high voltage Vo is turned on 1 Vo Decoupled over a capacity elementary charges deponized by the drift electrons on the anode surface
27. run queue modules can now read out and the data written into a file or IO stream Finally the veto line SVT is deactivated and the handler suspends again If a veto line is active no further interrupts can be generated To avoid inter rupts after the detection of the first initial trigger a further hardware switched veto line HVT is set by a flip flop circuit as long as the veto line SVT is deac tived again This circuit is also placed in the COC module together with the coincidence circuit and the PMT power supplys 12 CHAPTER 2 DRIFT CHAMBER HARDWARE Chapter 3 Drift Chamber Software 3 1 Overview As shown in the figure below the control and readout software includes a part processed on the real time operation system HP RT and another part on a LINUX system Both parts are written in one program text segment so that mostly all functions are available for each side Operation system specific parts are separated by compiler directives or specific loaded from libraries LINUX HP RT Database VME modules File system lt Event Display y H i Analysis Tools _ vme s vme s vme c st gt 1 SIGIO SIGIO console x inetd inetd console vme driv kernel kernel Figure 3 1 Drift Chamber Readout an
28. ry point functions and allows the VME module initial ization and readout completly independent from the main program A detailed description is given in the next chapter 3 4 LIBRARY 19 3 4 library vme_lib control a wide range of different module types only a place holder array dev lst must be delivered to the libraries entry point functions A linked list of modules with comparable functionality can now attached to the appropriate array field field number 0 1 2 3 4 5 6 7 module type DMC TDC DIS DPL GDU IOR direct memory access cards ADC analog to digital converters TDC time to digital converters DIS discriminators DPL dual programmable logic units GDU gate and delay units input output registers HVM high voltage modules It is therefore possible to initialize several module types from one or different configurations Each time a module definition line is parsed the given num ber of memory blocks is allocated appended to the appropriate list field and initialized with the following module parameters as shown in the example below TDC V767 1 module definition line TDC ADR 0x050000 TDC address TDC ADM 0x39 TDC address modifier TDC_IVC 0x00 TDC interrupt vector TDC_ICP ICP_DIS TDC interrupt capability TDC_CHN SFFFSFFF OFFFOFFF OFFFOFFF 00000000 TDC channel mask TDC_TRG 0x1F TDC reference channel TDC_RMD COMMON STOP TDC run m
29. sgets and sputs allow to handle database tables and sockets in the same way as defined for the standard file handling During the program run time the appropriate function set is called With an additional format param eter in dopen it is also possible to create database tables with more then only one column and different column types A more detailed description is given in D 3 6 State and Event Log Interface Optional event data and or state information can be written in parallel into a file or a database table This can be enabled or disabled with the global paramters VME_ELOG for event logs and VME_SLOG for state logs If an event display runs at the data receiver host the IPC system shown in B 2 signals each new event The event display acts here as a server process and is responsible to create to initialize and finally to release a shared memory device 3 7 Event Display The event display runs independent from the readout system and presents in the default online mode each new data event Additional it is possible to process raw data files also the files taken with the LeCroy TDCs in offline mode simulation In both modes the display process can be suspended and later continued Two types of event counters are available a relative counter that can be reset at any time and an absolute counter A short program description is given in Appendix C Chapter 4 Conclusion and Outlook With the new drift chamber ha
30. vme_lib If the interrupt line of the VME system becomes active the kernel breaks and continues with an interrupt acknowledge cycle Underlying kernel functions read out the interrupt level and vector of the VME interrupt generator module If level and vector matches the drivers internal interrupt service routine ISR is processed The SVT veto line is set the VME modules interrupt registers are reset the interrupt line is cleared and the ISR sends to the handlers the signal SIGIO gt vme_dev_isr vme_driv The handler process is suspended sigwait state until this time 3 2 HP RT DEVICE DRIVER 15 Now this process can continue and read out all run queue attached modules If this is completed the handler sets the interrupt registers again and deactivates the SVT veto line gt vme_set_vto vme lib It s now possible to repeat the interrupt cycle at the next valid trigger 16 CHAPTER 3 DRIFT CHAMBER SOFTWARE 3 3 Main Program Core of the main program independent from the run mode is a finite state machine FSM processed as followed sta n F cmd n f sta n m mel N sta FSM state out n F sta n m 0 FSM output cmd n 1 F out n sta n cmd FSM input To each new state can attached an output function The return value is the following input command FSM loop ends at failure or if the new state is equal to the initialization state transfer data between attached processes an
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