Current Status of MDC Track Reconstruction MdcPatRec Zhang Yao, Zhang Xueyao

Content Outline of Mdc pattern recon. Track parameters stored to TDS Problem in segment finding Latest result To do Summary

BESIII Main Drift Chamber (MDC)

Packages MdcTrkReconTrack-finding and fitting package BesGeom (NOT service anymore) Interface of MdcGeomSvc TrkBaseCore classes for common tracking code. TrkFitterCore classes for charged-particle tracking MdcDataHit and Hot ProbToolsThe chisq-consistency support MdcRecoUtilOther classes used in Reconstruction ProxyDictProvide a data store MdcCalibt->d calibration of the Mdc BfieldModeling the magnetic field

Reconstruction Status Segment finding and fitting ( ) Track Finding : 3-D tracking ( ) Track Finding : 2-D tracking ( ) Debug (now)

Sequence of Segment Finding Form groupword of 8 wires Try 4 hit and 3 hit patterns Do line fit to segments Store segment lists

Sequence of Track Finding Combine Axial segs to circle track Circle Fitting Combine Stereo segs to helix track Helix Fitting

Track Object RecoTrk : a track object TrkRep : path-description object HitOnTrack (HOT) : list of hits

Track Parameter Babar BesIII

Track parameter conversion

Store tracks to TDS MdcTrack 1. 5 track parameters 2. position of pivot //?? 3. error matrix for track parameters 4. chi square of helix fit 5. number of degree of freedom for the fit 6. number of total hits contained 7. number of stereo hits contained 8. mass of this particle //?? Pid 9. hit list of the track 10. phi value at track terminated point (Thank Wang Liangliang ‘s help!) 11. status flag

Store tracks to TDS MdcRecHit 1. drift distance left 2. drift distance right 3. error of drift distance left 4. error of drift distance right 5. contribution to chi square 6. flag indicating left or right 7. MDC identifier 8. corrected ADC 9. corrected TDC 10. tracks containing this hit 11. status flag

Interface DriftDist = 1.0e-4*40.0*driftTime;//cm MdcHit::driftDist(tof, ambig, entranceAngle, dipAngle, z) MdcHit::driftDist(bunchTime, ambig) bunchTime+crudeTof Sigma =0.013; //cm MdcHit::sigma(driftdist, ambig, entranceAngle, dipAngle, z) MdcHit::sigma(driftdist, ambig) T0 = 0.0 Bfield = BFieldFixed(0.0,0.0,1.0)

MdcPatRec Documentation

Preliminary Results for 1.0 GeV μ ( ) Released in boss Tracking efficiency:80% Distribution of and after 3-D helix tracking σ = 21 MeV / c σ = 12mm

The efficiency of segment finding rely on “neighbor”s finding Original construct 8 bit groupword according to a reference wire by id CAN NOT construct by wire id in superlayer 1~5 Modify segment construct clockwise (2,0)(2,1)(2,2)(2,3)(2,4)(2,5) (1,0)(1,1)(1,2)(1,3)(1,4)(1,5) (3,0)(3,1)(3,2)(3,3)(3,4)(3,5) (0,0)(0,1)(0,2)(0,3)(0,4)(0,5)

Modify segment construct Use phi of reference wire get “neighbors” Take 2 reference wire Layer 2 and layer 0 take No. 2 wire as reference wire Layer 3 take No. 4 wire as reference wire Layer id neighbor wire

Modify segment construct Verify the segment All segments can pass this test Almost all hits can form segment NEED check ambiguity Layer id Phi of No. 1 wire

Result for 1.0 GeV μ ( ) Tracking efficiency > 99% Distribution of and after 3-D helix tracking = 6 Mev/c σ = 1.9mm

Lost segments at –X Do a line fit to segment. The domain of is Huge chisq in –x If hits in segment cross –x axis and < 0 All segments cross –x can be found Thank Yu Guowei ‘s help! One MC Truth Hit

Latest result of MdcPatRec ( ) MC events P :1GeV single track cos(theta) :( ) Wire resolution :smeared with 130 mocron Particle:muon+,e+ BESIII’s goal:

e(+) smeared1 track efficiency >99.8% Mean = = 5.8 Mev/c= 4.9 Mev/c= 0.125mm

e(+) smeared2 track efficiency >99.8% = 1.89mm Mean = Mean = 0.45mm

Muon(+) smeared1 track efficiency >99.8% Mean = = 5.7 Mev/c= 4.6 Mev/c= 0.125mm

Muon(+) smeared2 track efficiency >99.8% = 1.88mm Mean = Mean = 0.4mm

To Do Sign of d0 Pivot and FiTem Store status and residual to TDS Lost hits of inner layers Shift of d0 Spacial resolution Hit ambiguity Sigma and Bfield Interface Find detector concerned value in code Delete AList,Pdt, ProxyDict … in my own package

Summary Released in boss Almost all track parameters have been put into TDS Modify some algorithm in segment finding Reconstruction results are acceptable Much work to do with algorithm and code

Thank you!