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The BESIII Offline Software

The BESIII Offline Software. Weidong Li Institute of High Energy Physics, Beijing Workshop on the cooperation of PRC-US in HEP 16 June 2006. BESIII Experiment. Main Drift Chamber (MDC)：  xy = 130  m  P/P = 0.5 %@1 GeV  dE/dx = 6-7 %. Super-conducting Magnet： 1.0 Tesla.

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The BESIII Offline Software

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  1. The BESIII Offline Software Weidong Li Institute of High Energy Physics, Beijing Workshop on the cooperation of PRC-US in HEP 16June 2006

  2. BESIII Experiment Main Drift Chamber (MDC)： xy = 130 m P/P = 0.5 %@1 GeV dE/dx = 6-7 % Super-conducting Magnet：1.0 Tesla TOF System： T = 90 ps barrel 110 ps endcap Muon Chamber (MUC)： RPC based EM Calorimeter (EMC)：E/E = 2.5 % @ 1 GeV 　 z, = 0.6 cm @ 1 GeV

  3. Software Environment • Underlying framework • GAUDI (originally developed by LHCb) • Simulation • GEANT4 • Other external LIBs: • CERNLIB, CLHEP, ROOT, AIDA, XercesC, GDML … • Database: MySQL • Computer language: C++ (BESII legacy code written in Fortran ) • Operation system: • SLC3/ gcc3.2.3 • Reused part of code from Belle, BaBar, ATLAS,GLAST

  4. Installation area package package Release area package package package package package package sources CVS package package package package cmt Work area binaries generated External External External External cmt CMT and CVS • Internal software • External software • HEP software • Public domain software

  5. Gaudi Infrastructure • The application has an ApplicationMgr and it creates and initializes a set of services. • The EventLoopMgr controls the main physics event loop and schedules execution of algorithms. • We have implemented many BESIII specific Algorithms and Services.

  6. Execution Sequence Detector Data Flow Event Data Flow MdcRec TofRec Raw Data RawData CnvSvc TofGeom Svc MdcGeom Svc EmcGeom Svc MucGeom Svc Geometry GDML Data Event Data Service EmcRec RootDst CnvSvc DST Data MucRec Navigation Svc Magnetic FieldSvc PartProp Svc Framework

  7. Event Data Generator • HEPEVT Data • Kinematics information only • RAW Data • Delivered by DAQ for reconstruction • Byte stream format • Simulated Event Data • Contain digits, hits and other MC truth information • Root format/byte stream format • REC & DST Data • Reconstructed Data is event data written as output of reconstruction procedure • DST Data is a reduced event representation suitable for analysis • Both in ROOT format HEPEVT Data G4 Simulation RAW Data Simulated Event Data Reconstruction REC & DST Data

  8. Tube & Endplate • constructed use Tube solid • Axial layers: Tube Solid • Stereo layers: Hype • Stereo Cells：TwistTube Simulation (1) • MDC • TOF • Scintillator (EJ200) • Wrapping materials (Al + PVF) • PMT (R5924) end-cap barrel

  9. Simulation (2) • EMC • G4Trap & G4IrregBox • Added cables,support system • Digitization: readout electronics is simulated • MUC • Detector description detailed to a single strip • One dimension read-out • Efficiency added according to position of pad

  10. Simulation (3) Generator • Generators are legacy code from BES/BESII experiment • Generators communicate with detector simulation through Gaudi Transient Data Store. Event 1 (BesGenModule) Gen Kine Inform. 2 McTruth Simulation (BesSim) 3 Digi Digi & Recon 4 McTruth Reconstruction Dst (MdcPatRec...) Transient Data Store Algorithm

  11. Reconstruction Algorithms

  12. Reconstruction algorithm Simulation algorithm GUI Client MySQL database CalibFunc Svc CalibRoot CnvSvc Calibration Algorithm Calibration Data Service Calibration constants (ROOT) Calibration • Recon. and simulation algorithms retrieve calibration data from calibration data store • Meta-data stored in database contains: path, valid run interval • Calibration constants are stored in ROOT files

  13. Event Display Tool: BesVis • Based onROOT, OpenGL, X3DandXML • Support both 2D and 3D view • Operations and controls available through menu and toolbar items • Recently MCTruth information was added.

  14. Physics Analysis Software • Analysis Object Builder • Particle Identification • Kinematics Fitting • Vertex Finding

  15. Major Releases • BESIII alpha release • integration with BOOST simulation • Running the reconstruction chain for MDC, TOF, EMC and MUC can be achieved in the BESIII Gaudi framework. • EDM for both Raw Data and reconstructed data developed. Completion of fully functional Event Data I/O. Status: published in May, 2005 • BESIII beta release • Simulation and reconstruction chain functions reasonably well and can successfully process thousands of events. • Common physics analysis tools and utilities available. • Physics study can start. Status: published in November, 2005

  16. Event Data Flow

  17. Performance (1) • TOF • reconstruction eff. ~99% (1GeV electron) • time resolution: ~110 ps • MDC • momentum and spatial resolutionσxy = 110 μm, δpt/pt = 0.4% (1GeV μ) dE/dx= ~6% 1 GeV π

  18. μefficiency 90 70 50 40 30 π(fake μ ) Performance (2) • MUC • Recon. efficiency: ~ 99% @ 1GeV • Ratio of fake μ < 10% for π • EMC • σE/E ≈ 2.8%@1GeV • σz = 0.6 cm@1GeV

  19. BESIII Software Timeline

  20. Ongoing Activities • Detector alignment survey • Mixing of background events • Reconstruction performance optimization • Studies of algorithms’ robustness • With background pileup • miss-alignment • Non-uniform magnetic field • Data Challenges

  21. Summary • BESIII has successfully adopted GAUDI application framework. • Based on Gaudi, the BESIII offline software was developed • Simulation • Calibration and reconstruction • Physics analysis • Data challenge and software performance optimization are the major task for 2006.

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