1. BESIII Simulation Status Z.Y. Deng M. He H.M. Liu Y.J. Mao Z.Y. You Y.Yuan BES Annual Meeting June 1, 2005

2. 2/34 Outline  Introduction  Current status  Performance  Future work  Summary

3. 3/34 Geometry Geant4 Tracking Detector Digitization Response Hit objects Event GENBES Generator HepEvt format Raw data MC truth BOOST Project ( BESIII Object Oriented Simulation Tool)

4. 4/34 BOOST Project ( BESIII Object Oriented Simulation Tool)  Components  Generator  Particles and physics processes  Magnetic field  Material  MC truth  Data I/O  User interface  Geometry  Hits recording  Digitization sub-detector parts common parts

5. 5/34 boost/ bes/ common part src/ source c++ codes include/ header files gen/ … event generators phy/ … physics processes tru/ … MC truth gmk/ … common makefiles mac/ … common card files dat/ … geometry data files exe/ … main program for execution doc/ … documentations mdc/ … main drift chamber tof/ … time of fight emc/ … electromagnetic calorimeter muc/ … muon chamber BOOST code structure

6. 6/34 BOOST Project ( BESIII Object Oriented Simulation Tool)  Developers  Liu Huaimin: common parts  Yuan Ye: MDC  Deng Ziyan: TOF & common parts  Fu Chengdong/He Miao: EMC  Peking University: MUC & xml geometry

7. 7/34 BOOST Project ( BESIII Object Oriented Simulation Tool) Phase 1: Framework prototype, simple geometry with hit Finished, BOOST prototype realized in May,2003 Phase 2: Detailed detector with simple digitization Finished, now digits and MC truth output can be used for reconstruction  Phase 3: Detailed digitization, data/MC comparisons  In progress, need information from beam test and data. A long-term work!

8. 8/34 Geant4 and BOOST releases  Geant4  Release 6.1 March, 2004  Release 6.2 June, 2004  Release 7.0 December, 2004  Patch of 7.0 February, 2005  BOOST (mantained by cvs)  ‘boost-1-0’ (March, 2004) -----Geant4.6.1  ‘boost-1-1’ (June, 2004) -----Geant4.6.2  ……  ‘boost-2-0’ (February, 2005) ----Geant4.7.0  ‘boost-2-1’ (May, 2005) ----- Geant4.7.0+p01

9. 9/34 BOOST Current Status geometry  Detailed BESIII geometry is constructed in BOOST  Geometry added since last annual meeting  Accurate stereo cells in MDC  New End-cap EMC  SCM (Super-Conducting Magnet )  BESIII Geometry in XML format  Geometry in BOOST now can also be constructed with XML  Simulation, reconstruction, event display will share the same BESIII geometry  See detailed information in Mao Yajun’s report

10. 10/34 BOOST Current Status MDC stereo cell  Accurate description  New class (J4TwistedTubs) introduced  all stereo wire cells are constructed  Display for checking  Twisted tube can’t be displayed directly  hit positions in stereo cell used  3D scatter plot with ROOT package

11. 11/34 BOOST Current Status end-cap EMC geometry  Quadrangular crystal  Irregular boxoid  Can’t be described by existing classes in Geant4 releases  New class (G4IrregBox) introduced  Pentangular crystal  Divided into 2 boxoids  2 boxoids share the same copy number quadrangular crystal pentangular crystal

12. 12/34 BOOST Current Status end-cap EMC geometry  construct all crystals in one sector  Place other sectors through rotation and reflection  Rotate east end-cap to place west end-cap end-cap EMC sector rotation reflection

13. 13/34 BOOST Current Status geometry From boost-2-1 barrel: MDC, TOF, EMC, SCM, MUC end-cap: TOF, EMC, MUC

14. 14/34 BOOST Current Status generator  genbes: (BESII generator system)  Generate events in an ASCII file which supports HEPEVT interface with Geant4  The same user interface as BESII genbes.cards, genbes.user  All BESII generators can be used in BOOST  tester: (single-particle generator for debugging)  Shoot particles of given type  to a given direction  with given kinetic energy  Users can randomize above quantities

15. 15/34 BOOST Current Status generator: howl J/ψ  K s K s  π + π - π + π - Hits in MDC Hits in barrel TOF (no threshold cut) Hits in end-cap TOF Hits in end-cap MUC

16. 16/34 BOOST Current Status generator: rhopi J/ψ  ρπ  π + π -  Hits in barrel MUC (π- punch through) Shower in EMC gamma

17. 17/34 BOOST Current Status processes & magnetic field & material  Physics processes  BesPhysicsList constructed with Geant4 classes  Many hadronic models installed, LHEP, LHEP-GN, QGSP-GN, ……  More research on them needed to choose suitable ones for BESIII physics  Magnetic field  1 Tesla uniform magnetic field defined inside SCM  Material  All materials needed in BOOST defined in XML

18. 18/34 BOOST Current Status hits and digitization  Hits recording  Finished last year  digitization  MDC Drift distance-> drift time dE/dx Wire resolution added Simple background added  TOF Detailed digitization Light emission & light propagation PMT response & threshold discrimination  EMC waveform added Simulate main amplifier output Provide risetime to eliminate noise No noise, so not used now  MUC Digit information added

19. 19/34 BOOST Current Status MC truth  Purpose  To provide truth information for reconstruction debugging  Similar to MCMADE in BESII  What to save  True state of the particles and their association with detector response Particle particles from generator uninterrupted decayed daughters Detector response hits in sub-detectors associated with particles

20. 20/34 BOOST Current Status MC truth  Track and vertex (associated with particle)  Track PDGcode charge original vertex terminal vertex four-momentum decayed daughters  Vertex parent track position time  truth hits (associated with track)  Considering demand of each reconstruction developer  MDC Hit history  TOF First-hit  EMC Total energy loss  MUC Hit history

21. 21/34 BOOST Current Status Data I/O  Ascii data I/O  It’s temporary, but useful in software (SIM + REC) development  Ascii data format fixed for the moment  MC truth (TRUTH) & Raw data (DIGI) included in one file EVHEAD TRACKTRUTH, VERTEXTRUTH MDCTRUTH, MDCDIGI TOFTRUTH, TOFDIGI EMCTRUTH, EMCDIGI MUCTRUTH, MUCDIGI  Users can turn on/off TRUTH and DIGI part of each sub-detector in run cards

22. 22/34 BOOST Current Status User interface  Friendly to both users and developers  source ~dengzy/.boostenv  cvs co boost  edit boost.cards & boost.user  more controls in run cards  Run background/terminal/interactive/PBS job freely  boost -b/-t/-i/-q  use ‘boost –h’ for detail  Reconstruction developers can generate needed data files themselves

23. 23/34 BOOST Performance Speed  From LHC experience  G4 direct comparison with G3  G4 is slower (1.5~2) than G3  G4 tracking particle to 0 energy  Compared with SIMBES  SIMBES (G3/BESII), BOOST (G4/BESIII)  How to compare  Similar cuts CUTE CUTM (10KeV), range cuts (1mm)  Same platform (Besfarm7)  Physics events used (dimuon, rhopi, bhabha)

24. 24/34 BOOST Performance Speed CPU time (s) for one event Besfarm7 (PIII/933) EventSIMBESBOOST ee -> uu 0.1220.189 J/ψ->ρ π 0.4710.763 ee -> ee 0.7361.224  BOOST 1.5 times slower than SIMBES  More to do about speed improvement  Threshold cut in digitization  Speed of hadronic models to be compared  Stable (no crash for 100,000 events)

25. 25/34 BOOST Performance MDC P distribution (1GeV/c e-) σ p =6.1MeV P distribution (1GeV/c mu-) σ p =5.8MeV Reconstruction result using BOOST data sample

26. 26/34 1GeV/c e- vertical incidence total energy loss in one scintillator ( 5cm width ) BOOST Performance TOF

27. 27/34 BOOST Performance TOF e- 1GeV/c Z=0 : forward TDC resolution = 121ps backward TDC resolution = 122ps T : 1/sqrt(Q) time-walk forward backward

28. 28/34 BOOST Performance TOF e μ π k p  Randomly generate particles: e-, mu-, pi-, kaon-, proton  Momentum: uniform between 0-1.6 GeV/c  Only intrinsic time resolution

29. 29/34 BOOST Performance EMC total energy loss of pi- e-

30. 30/34 BOOST Performance MUC Probability of single particle(μπ) entering MUC

31. 31/34 BOOST Integration to BOSS framework  Different developing environment  BOOST On besfarm Configured with gmake Based on GEANT4  BOSS On koala Configured with CMT Based on GAUDI  Integration Status  BOOSTAlg algorithm/packages created in BOSS  Key functions of BOOST realized in BOSS  Interface of saving data to TDS is ok  Codes imported into cvs

32. 32/34 Future Work  Move developing environment from besfarm to lxplus  Magnetic field mapping  Physics validation, optimization  Data I/O  Objectivity?  Raw data in online format, MC-Truth format?  Background, noise?  Detailed detector response

33. 33/34 Summary  Detailed BESIII detector is built in BOOST  All BESII generators can be used in BOOST  Raw data/MC-truth data are successfully used in reconstruction  Friendly user interface  BOOST integrated into BOSS  Prototype of TOF detailed digitization is realized  More to do about detector response !

34. 34/34 Thank you !