April 27-29, Hangzhou1 STAR time-of-flight detector Calibration Ming SHAO USTC

April 27-29, Hangzhou 2 Detectors TPC(TPX) - tracking MRPC TOF (TOFr) – stop time measurement pVPD/upVPD - start time measurement 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 TOF system 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 Run VRun VIIIRun IX MRPC TOF TPC X Y pVPD upVPD Z

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, total Schambach Jo et al., Int. J. Mod. Phys. E

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

April 27-29, Hangzhou 6 Time-TOT Correlation Leading-edge timing signal, trailing-edge signal width (TOT) time Amp. T 1l T 2l T 2t T 1t Thre. Time stamp Leading-edge trigger, signal charge (ADC) is measured for correction time Amp. T1 T2T1 T2 Thre. Q1Q1 Q2Q2

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

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

April 27-29, Hangzhou 9 VPD calibration procedure

April 27-29, Hangzhou 10 TDC-TOT correlation Use spline fit (3rd polynomials TSplineFit based on ROOT, developed by François-Xavier Gentit)TSplineFit Run VIII, 200 GeV pp Run V, 62.4 GeV CuCu TDC 1 – (TDC 2 +TDC 3 )/2 (ns) TOT (ns)

April 27-29, Hangzhou 11 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) Beam line Vertex Z z T 0 +(L/2-V z )/c T 0 +(L/2+V z )/c West East upVPD CP

April 27-29, Hangzhou 12 Resolution before/after calibration ~6 ns~0.16 ns Before calibration After calibration TDC 1 – (TDC 2 +TDC 3 )/2 (ns) Run VIII 200 GeV pp Zebo Tang

April 27-29, Hangzhou 13 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) TOFr Calibration procedure Try channel-by-channel first Not enough statistics? Then try module-by-module, or board-by-board

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

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

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

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 Operation condition Time Resolution (ps) pVPD TOFr (overall) TOFr (stop time) Run III 200GeV d+Au ~85~120~85 200GeV p+p ~140~160~80 Run IV 62GeV (Au+Au) ~55~105~89 200GeV (Au+Au) FF/RFF ~27~74~70 HF ~20~74~71 Run V 200GeV Cu+Cu (TOT) ~ 50~92~75 62GeV Cu+Cu (TOT) ~ 82~125~94 Run VIII 200 GeV d+Au NA 200 GeV p+p (TOT) ~83~112~75 Run IX 500 GeV p+p ~85~110~77

April 27-29, Hangzhou 19 Output calibration parameter 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 Bin boundary Same statistics in each bin

April 27-29, Hangzhou 20 #Events needed for calibration Collisions arXiv: ×1/4(pure pion) ×80% (match) ×2 (  ) Useable hits per channel #Events for channel- by- channel #Events for module- by- module #Events for board- by- board #Event s for T0 (500/ch annel) p+p (MB) e-5240 M40 M10 M12 M d+Au(MB) e-456 M9.3 M2.3 M2.8 M Au+Au(MB) e-32.9 M0.5 M0.12 M0.15 M Au+Au (0-10%) e-31.2 M0.2 M0.05 M0.06 M 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 Expectation (ideal) 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 T i 6 iteration of calibration

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 VPD Calibration  INL correction  TOT correction TOF tray Calibration  INL correction  T0 correction  TOT correction  Hit position (Z) correction Calibration database  INL table  T0 table  T-TOT table  T-Z table Calibration w/o VPD  Fast simulation  Data results Thank you !Thank you !Thank you !Thank you !

April 27-29, Hangzhou 24 Backup Slides

April 27-29, Hangzhou 25 VPD fired channels ~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) Run VIII 200 GeV pp Zebo Tang

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

April 27-29, Hangzhou 27 Calibration Procedure – before run V Leading-edge trigger, signal charge (ADC) is measured for correction time Amp. T1 T2T1 T2 Thre. Q1Q1 Q2Q2

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