Status of BESIII Event Reconstruction System Zepu Mao IHEP BESIII Annual Meeting 2005/05/29

The Modules and General Flow TOF Rec MuC Rec. Veefind Evtvert Fast-TrackEvent-TimeMDC-TrackEvent-TimeTrack-FitdE/dx-RecTrac-Ext MDC Tracking Cluster Match Gamma Pi0 EMC Rec Phy. Vertex

MDC Fast Tracking Module  x  160  m  z  6mm  p  10MeV Trk Eff  99%  x  160  m  z  6mm  p  10MeV

Event Time Module Status  Due to the trigger system can’t separate the events from beam bunch, the time of Events starts point need calculate in offline system by the geometry of TOF and MDC. MDC Tracks MDC TOF Raw Tof Infor. EvTime-TOF EvTime-MDC yes no yesno EvTime-MDC0 EvTime-MDC and EvTime-TOF: passed the testing by MC data using the information of MDC fast tracks.  EvTime-MDC0: for “No MDC Fast tracks” events is studying

MDC Tracking Module(1) (based on Belle)  Init: Geometry-Surv., Cal.-Constant, Adjust-constant Get Hit Information ….  R-  Tracking: Segment finding by conformal transformation and histogram method  Z Finding  3D Helix Fit Circle & Line Fit

Status MDC Tracking Module (1)  z0  2 mm  x  140  m  D0  180  m  p  6MeV TRK Eff  99%

MDC Tracking Module(2) (based on Babar)  Init: Geometry-Sur., Cal.-Constant, Adjust-constant Get Hit Information …. Link segments to 2-D tracks, 3D Helix Fit Line & Circle Fit  Tracking:  Segment finding: Search segments in each super-layer using a pattern look-up table. Add stereo segments

Status MDC Tracking Module (2)  This module has been tested by MC data also.  The preliminary performance is:  p T  5.8 MeV TRK Eff  95%

Kalman filter track fitting package (based on the (BELLE Lib.)  Simplicity and flexibility in computation :  more reliable material effects and NUBF treatments  Optimal predictions from both ends  Easy outlier and ambiguity removal  Good match to OO design & programming Recursive procedure to estimate track parameters prediction filtering smoothering

Preliminary Results of Kalman Track fit  Helix parameters and error matrix is roughly reasonable.  Parameters of track consistent with MdcFastTrkAlg’s.  Parameters need further optimizing. Output Pull check Input Helix parameters from FastTrkAlg Output parameters from KalFitAlg proton events 1GeV/c  Package is migrated successfully on the BOSS V4.2, Five particle hypotheses is made; the simple B field and materials is updated with BESIII’s.  Passed the testing by the MC data: MdcFakeData & MdcFastTrkAlg.

Status of dE/dx Module  The Codes passed the MC test and migrated to BOSS 4.2  Different algorithms and truncation ratio are studied  Calibration Const. retrieved from DB, package in design  Corrections studied and par. to be optimized further Pi/K Pi/P 0.75GeV 1.3GeV dE/dx curve and resolution

Track Extrapolation Module  Function: Extrapolate MDC tracks to Outer detectors: TOF, Coil, EMC, MUC  Algorithm: based on GEANT4, Energy loss and Magnetic field. Multiple scattering effect put into error matrix.

Status TOF Reconstruction Module TofSys BTofSys ETofSys BTofMod BTofCnt BTofScint BTofPhotoTube ETofCnt ETofScint ETofPhotoTube ETofMod For 88 Counter For 96 Counter  TofRec package has been developed, and runs well on the BOSS v4.1 BOSS v4.1  By the signal electron the primary performance is: Time Res.  83 ps, Track Eff  100, Class structure of TofRec LAttenuation LAttenuation  3.2M

The Results of TOF Rec. Module Tracks found by TofRec from one MDC track. Trk Eff  100% Time resolution  83 Ps Attenuation Length  3.2m

Status of EMC Rec.  Clustering (Make Shower)  Gamma Rec.  Matching with MDC  Pi0 Rec.

MUC Reconstruction Module Finished the programming and preliminary testing by MC data using two way: MDC-Track Extrapolating and 2D/3D Road “2D/3D Road” : Tracking EF:  99% “Extrapolating” : Tracking EF  99%.

Summary Module Name Status MDC Fast track Trk-Eff  99 %,  x  100um,  z  4mm,  p  10MeV EvTime MDC-Track-1 Trk-Eff  99 %,  p  6MeV,  x  140  m,  z0  2 mm MDC-Track-2 Trk-Eff  95 %,  p T  5.8MeV dE/dx PID Trk-Ext Klmfit TOF Rec. Trk-Eff  100 %,  T  83ps, EMC Rec. Trk-Eff  100 %,  E  2%,   .007rad,    .008rad MuC Rec. Trk-Eff  99 % : Design, programming & testing : Passed the MC data testing : Performance checking and Par. Optimization stage

谢谢各位专家！ Thanks

Track Finding Algorithm  Conformal transformation. A circle which passes through the origin is transformed into a line.  Segments found by histogram of hit wires’ azimuthal angle  Track linking from the outmost to the innermost layer with the directions of segments and apply the circle fit.

MdcSegFinder Sequence For every superlayer and every wire in 2 nd layer form a group of 8 wires Try 4 hit pattern for this group Call tryPatterns() Try 3 hit pattern for this group Call tryPatterns() Set massage of segment list Sequence of segFinder::createSegs() For every group Wires No. 0-7  Set one word for a group of 8 wire, each bit for a wire.  Set “1” for a hit wire, others “0”  This octal value used for its group No.

Performance of EMCRec(1)  E  1.85 –1.95% The Code EmcRec has finished the design, programming and passed the MC data testing in the BOSS V4.0 (signal photon with energy 0.5, Gev) Performance: Eff:  100%    –0.007 rad    –0.008 rad    –0.007 rad    –0.008 rad  E  1.85 –1.95%

S-Z calculation in Z finding

Fig.6 Flow of R-phi track finding(left) and z finding(right)

BEPCII Milestones May. 04 – Oct. 04. : –Linac upgrade –BESII detector removed Nov. 04 – March 05: SR running April 05 – Jan. 06: Long shutdown –Remove existing ring –Install two rings –Cryogenics system ready for SC devices, field mapping Feb.- Sep. 06: Tuning of machine + SR running Oct. 06 : BESIII detector moved into beam line Nov. 06 – Feb. 07 : Machine-detector tuning. Physics run by March 2007

BES III 离线软件系统研发时间线

Status MDC Tracking Module (2)  p  20 MeV  z0  14 mm  D0  500  m TRK Eff  95%