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STAR time-of-flight detector Calibration

STAR time-of-flight detector Calibration. Ming SHAO USTC. TPC(TPX) - tracking. pVPD/upVPD - start time measurement. MRPC TOF (TOFr) – stop time measurement. Detectors. Particle momentum; dE/dx. ~8% resolution /K separation to ~0.6GeV/c k/p separation to ~1.0GeV/c.

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STAR time-of-flight detector Calibration

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  1. STAR time-of-flight detector Calibration Ming SHAO USTC April 27-29, Hangzhou

  2. TPC(TPX)- tracking pVPD/upVPD - start time measurement MRPC TOF (TOFr) – stop time measurement Detectors Particle momentum; dE/dx ~8% resolution /K separation to ~0.6GeV/c k/p separation to ~1.0GeV/c Aim at 100ps time resolution (TOF system) /K separation to ~1.6GeV/c & k/p separation to ~3.0GeV/c April 27-29, Hangzhou

  3. Y X TPC TPC TOF system Run V Run VIII Run IX Z pVPD upVPD upVPD pVPD MRPC TOF pVPD/upVPD consists of plastic scintillators + fast PMTs, 5.4~5.7m from TPC geometry center along the beam line 3 channels each side (runV and before) to 19 channels each side (after runV) Full barrel TOF consists of 120 trays, 32 MRPC modules per tray, 6 channels per module Only one tray in run V, 5 trays in run VIII and 94 trays in run IX April 27-29, Hangzhou

  4. New TOF electronics 2 THUB per side, 4 total 1 TCPU per tray/pVPD, 122 total 1 TPMT/TDIS per pVPD, 2 total 8 TINO/TDIG per tray, 960 total 24 chn. per TINO/TDIG, 23040 total Schambach Jo et al., Int. J. Mod. Phys. E 16 2496 April 27-29, Hangzhou

  5. HPTDC INL Correction Integral Non-Linearity DifferentialNon-Linearity Jing Liu April 27-29, Hangzhou

  6. Leading-edge timing signal, trailing-edge signal width (TOT) Leading-edge trigger, signal charge (ADC) is measured for correction Amp. Amp. Q1 Thre. Thre. Q2 T1lT2l T2tT1t time T1T2 time Time stamp Time-TOT Correlation April 27-29, Hangzhou

  7. Related software update Calibration results Thanks Xin Dong etc. April 27-29, Hangzhou

  8. VPD W.J. Llope Collision Point • All hits in the same event arrived at the same time • As reference for each other VPD PMTs April 27-29, Hangzhou

  9. VPD calibration procedure April 27-29, Hangzhou

  10. TDC-TOT correlation TDC1 – (TDC2+TDC3)/2 (ns) Run VIII, 200 GeV pp Run V, 62.4 GeV CuCu TOT (ns) TOT (ns) Use spline fit (3rd polynomials TSplineFit based on ROOT, developed by François-Xavier Gentit) April 27-29, Hangzhou

  11. T0+(L/2+Vz)/c T0+(L/2-Vz)/c East West z CP Beam line Vertex Z upVPD upVPD Global offset tune • Slewing effect correction was done on east/west side separately • Absolute time from east/west side are floating • Tune the global offset between east/west side to match Vz(VPD) with Vz(TPC) April 27-29, Hangzhou

  12. Resolution before/after calibration Zebo Tang ~6 ns ~0.16 ns Before calibration After calibration TDC1 – (TDC2+TDC3)/2 (ns) TDC1 – (TDC2+TDC3)/2 (ns) Run VIII 200 GeV pp April 27-29, Hangzhou

  13. TOFr Calibration procedure • Choose  sample by limiting dE/dx and momentum range (or pre-calibrated TOF) • T0 correction, different cable length and signal transition time • TOFr TOT and Z position calibration, using charged pion sample. • Iteration several times (if needed) • Try channel-by-channel first • Not enough statistics? Then try module-by-module, or board-by-board April 27-29, Hangzhou

  14. Comts TOFmeasured – TOFexpected (ns) T0 correction Zebo Tang Run VIII 200 GeV pp Channel-by-Channel Simple Gaussian function Fit Shift the mean of TOFmeasured – TOFexpectedto 0 April 27-29, Hangzhou

  15. TOFr TOT slewing correction TOFmeasured – TOFexpected (ns) TOT (ns) Run V 200GeV CuCu Signal ringing effect Run VIII 200GeV pp Better signal termination achieved TOT (ns) April 27-29, Hangzhou

  16. Run VIII 200 GeV pp Finite signal propagation speed vs. hit position TOFmeasured – TOFexpected (ns) Hit Position Z (cm) Run V 200 GeV CuCu Readout MRPC strip Hit position (Z) corrction April 27-29, Hangzhou

  17. TOF Time Resolution Run V CuCu 62.4GeV Run V CuCu 200GeV Run VIII pp 200GeV April 27-29, Hangzhou

  18. TOF resolution summary April 27-29, Hangzhou

  19. Output calibration parameter Bin boundary Same statistics in each bin • Inconvinient to retrieve and use the parameters of all of the Splines • Upload each TOT bin boundaries and the corresponding corrections • Interpolate in each TOT bin April 27-29, Hangzhou

  20. #Events needed for calibration 10 K for slewing correction Note 1: in pp collisions, the upVPD efficiency is only ~40% when requiring >=2 hits on both sides Note 2: dN/d asymmetry in dAu collisions April 27-29, Hangzhou

  21. TOF calibration w/o start detector Fast simulation Single channel resolution: 90ps Time-TOT/Z correlation taken from real data T0 obtained by direct average of Ti 6 iteration of calibration Expectation (ideal) April 27-29, Hangzhou

  22. T0 resolution w/o start detector – from data Run V 62.4 GeV CuCu After 6-round calibration iteration April 27-29, Hangzhou

  23. Summary • Calibration database • INL table • T0 table • T-TOT table • T-Z table • Calibration w/o VPD • Fast simulation • Data results • VPD Calibration • INL correction • TOT correction • TOF tray Calibration • INL correction • T0 correction • TOT correction • Hit position (Z) correction Thankyou! April 27-29, Hangzhou

  24. BackupSlides April 27-29, Hangzhou

  25. VPD fired channels Run VIII 200 GeV pp Zebo Tang • ~35% events have >=3 hits on either side (useable for calibration) • ~40% events have >=2 hits on both sides (better start time or • ~15% events have >=3 hits on both sides Vz resolution) April 27-29, Hangzhou

  26. Track projection and Vz correlation Vertex from track projection (No vertex from TPX): project tracks matched to TOF hits, get the closest position to beam line. Beam line uncalibrated, fix to (0.5,0) cm Should be different between fills Unnecessary to parallel to z direction 2D DCA April 27-29, Hangzhou

  27. Amp. Q1 Thre. Q2 T1T2 time Calibration Procedure – before run V Leading-edge trigger, signal charge (ADC) is measured for correction April 27-29, Hangzhou

  28. pVPD Calibration –start time April 27-29, Hangzhou

  29. TOFr Calibration –MRPC TA & TZ TA slewing correction Hit position (TZ) correction 7th-order polynomial April 27-29, Hangzhou

  30. Time resolution determination Increase with n (assume equal time resolution for each channel) April 27-29, Hangzhou

  31. Calibrated time resolution April 27-29, Hangzhou

  32. Hadron PID April 27-29, Hangzhou

  33. Electron PID April 27-29, Hangzhou

  34. Muon PID 200 GeV CuCu April 27-29, Hangzhou

  35. Run-VIII PID 1.2<p<1.4 GeV/c April 27-29, Hangzhou

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