Current Status of MDC Track Reconstruction Mdc Pat

Current Status of MDC Track Reconstruction Mdc. Pat. Rec Zhang Yao , Zhang Xueyao 2005 -09 -07

Content Outline of Mdc pattern recon. l Track parameters stored to TDS l Problem in segment finding l Latest result l To do l Summary l yzhang@hepg. sdu. edu. cn 2

BESIII Main Drift Chamber (MDC) yzhang@hepg. sdu. edu. cn 3

Packages l l l l l Mdc. Trk. Recon Bes. Geom Trk. Base Trk. Fitter Mdc. Data Prob. Tools Mdc. Reco. Util Proxy. Dict Track-finding and fitting package (NOT service anymore) Interface of Mdc. Geom. Svc Core classes for common tracking code. Core classes for charged-particle tracking Hit and Hot The chisq-consistency support Other classes used in Reconstruction Provide a data store Mdc. Calib Bfield t->d calibration of the Mdc Modeling the magnetic field yzhang@hepg. sdu. edu. cn 4

Reconstruction Status Segment finding and fitting (2004 -12) Track Finding : 2 -D tracking (2005 -04) Track Finding : 3 -D tracking (2005 -04) Debug (now) yzhang@hepg. sdu. edu. cn 5

Sequence of Segment Finding Form groupword of 8 wires Try 4 hit and 3 hit patterns Do line fit to segments Store segment lists yzhang@hepg. sdu. edu. cn 6

Sequence of Track Finding Combine Axial segs to circle track Circle Fitting Combine Stereo segs to helix track Helix Fitting yzhang@hepg. sdu. edu. cn 7

Track Object l l l Reco. Trk : a track object Trk. Rep : path-description object Hit. On. Track (HOT) : list of hits yzhang@hepg. sdu. edu. cn 8

Track Parameter l Babar l Bes. III yzhang@hepg. sdu. edu. cn 9

Track parameter conversion yzhang@hepg. sdu. edu. cn 10

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

Store tracks to TDS Mdc. Rec. Hit 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. drift distance left drift distance right error of drift distance left error of drift distance right contribution to chi square flag indicating left or right MDC identifier corrected ADC corrected TDC tracks containing this hit status flag yzhang@hepg. sdu. edu. cn 12

Interface l Drift. Dist = 1. 0 e-4*40. 0*drift. Time; //cm l l Mdc. Hit: : drift. Dist(tof, ambig, entrance. Angle, dip. Angle, z) Mdc. Hit: : drift. Dist(bunch. Time, ambig) l l Sigma =0. 013; //cm l l bunch. Time+crude. Tof Mdc. Hit: : sigma(driftdist, ambig, entrance. Angle, dip. Angle, z) Mdc. Hit: : sigma(driftdist, ambig) T 0 = 0. 0 Bfield = BField. Fixed(0. 0, 1. 0) yzhang@hepg. sdu. edu. cn 13

Mdc. Pat. Rec Documentation http: //koala. ihep. ac. cn/~zhangy/Mdc. Pat. Rec. Doc 02/index. html yzhang@hepg. sdu. edu. cn 14

Preliminary Results for 1. 0 Ge. V μ (2005 -05) l l l Released in boss 4. 2. 0 Tracking efficiency: 80% Distribution of and σ = 12 mm after 3 -D helix tracking σ = 21 Me. V / c yzhang@hepg. sdu. edu. cn 15

Modify segment construct l l The efficiency of segment finding rely on “neighbor”s finding Original l construct 8 bit groupword according to a reference wire by id (3, 5) (2, 4) (1, 5) (0, 4) (3, 4) (2, 3) (1, 4) (0, 3) (3, 2) (2, 2) (1, 3) (2, 1) (1, 2) (0, 1) (3, 0) (2, 0) (1, 1) (1, 0) (0, 0) clockwise l CAN NOT construct by wire id in superlayer 1~5 yzhang@hepg. sdu. edu. cn 16

Modify segment construct l l 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 7 Layer id 5 3 6 4 neighbor wire 3 2 2 1 neighbor wire 1 yzhang@hepg. sdu. edu. cn 0 0 17

Modify segment construct l Verify the segment 1 Layer id 0 3 1 1 0 l l l 2 1 1 1 Phi of No. 1 wire 0 0 All segments can pass this test Almost all hits can form segment NEED check ambiguity yzhang@hepg. sdu. edu. cn 18

Result for 1. 0 Ge. V μ (2005 -07) l l Tracking efficiency > 99% Distribution of and after 3 -D helix tracking = 6 Mev/c σ = 1. 9 mm yzhang@hepg. sdu. edu. cn 19

Lost segments at –X l l l Do a line fit to segment. The domain of is Huge chisq in –x l l If hits in segment cross –x axis and <0 l l All segments cross –x can be found l Thank Yu Guowei ‘s help! One MC Truth Hit yzhang@hepg. sdu. edu. cn 20

Latest result of Mdc. Pat. Rec (2005 -09) l MC events l l l P: cos(theta) : Wire resolution : Particle: 1 Ge. V single track (-0. 8) smeared with 130 mocron muon+, e+ BESIII’s goal: yzhang@hepg. sdu. edu. cn 21

e(+) smeared 1 track efficiency >99. 8% = 5. 8 Mev/c = 4. 9 Mev/c Mean = 46. 25 = 0. 125 mm yzhang@hepg. sdu. edu. cn 22

e(+) smeared 2 track efficiency >99. 8% = 1. 89 mm Mean = 0. 45 mm Mean = 44. 38 yzhang@hepg. sdu. edu. cn 23

Muon(+) smeared 1 track efficiency >99. 8% = 5. 7 Mev/c = 4. 6 Mev/c Mean = 45. 78 = 0. 125 mm yzhang@hepg. sdu. edu. cn 24

Muon(+) smeared 2 track efficiency >99. 8% = 1. 88 mm Mean = 0. 4 mm Mean = 44. 36 yzhang@hepg. sdu. edu. cn 25

To Do l l l l l Sign of d 0 Pivot and Fi. Tem Store status and residual to TDS Lost hits of inner layers Shift of d 0 Spacial resolution Hit ambiguity Sigma and Bfield Interface Find detector concerned value in code Delete AList , Pdt, Proxy. Dict … in my own package yzhang@hepg. sdu. edu. cn 26

Summary l l l Released in boss 4. 3. 0 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 yzhang@hepg. sdu. edu. cn 27

Thank you!