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Zebo Tang University of Science and Technology of China (USTC)

MRPC-TOF R&D, calibration, performance and related physics at STAR. Zebo Tang University of Science and Technology of China (USTC). Outline. Introduction STAR MRPC-TOF R&D Calibration Performance PID and physics results achieved Summary & Outlook. STAR Detector.

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Zebo Tang University of Science and Technology of China (USTC)

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  1. MRPC-TOF R&D, calibration, performance and related physics at STAR Zebo Tang University of Science and Technology of China (USTC) STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  2. Outline • Introduction • STAR MRPC-TOF R&D • Calibration • Performance • PID and physics results achieved • Summary & Outlook STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  3. STAR Detector Large acceptance: 2 coverage at mid-rapidity Magnet Coils Central Trigger Barrel (CTB) ZCal Time Projection Chamber (TPC) Year 2000 Barrel EM Cal (BEMC) Silicon Vertex Tracker (SVT)Silicon Strip Detector (SSD) FTPCEndcap EM CalFPD TOFp, TOFr PMD Year 2001+ STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  4. GeV/cm 200 GeV Au+Au Resolution ~8% p K p e Why do we need a TOF? Specific Energy Loss in STAR TPC With the STAR TPC K p identification: p ~ 0.7 GeV/c Proton identification: p ~ 1.1 GeV/c S/N for f reconstruction: ~ 1/few 100 Multi-strange particles reconstruction efficiency: ~ 10-4 --10-3 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  5. TOF PID Capability (~220 cm from the Beam Line) R. Majka for STAR STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  6. Characteristic length: balance function, strangeness correlation What can TOF do at STAR? Baryon Transport: net baryons E-by-E Gluon Dynamics: K/p, p/p Dynamical Fluctuations: p/K/p Separation TOF Huan Huang Particle Composition Bulk Property: CGC? Evolution Dynamics Particle Correlations Exotic Particle Searches Elliptic Flow: p/K/p/L/f/X/W Heavy Quark: D,J/y HBT: pp, KK Jet Fragmentation: Baryon-meson PID Resonance:K*,r,D L(1520),S(1385),X(1530) Nucleosynthesis: 3He/t Di-baryon: H or L-L,W-W,[Xp] Unlike Particles: pK, pp and Kp. STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  7. Requirements 1) Good Time resolution The total resolution after all corrections must be <100 ps,for a start time resolutionof ∼50 ps, 30 ps contribution from slew correction, pure stop resolution of less than ∼80 ps. 2) High Granularity（dN/dy~1000 in central Au+Au) The detector segmentation must be such that the occupancy per channel is < 10%. 3) The system must be able to operate at particle fluxes up to ∼200 Hz/cm2. 4) The system must be able to operate inside the STAR magnetic field. 5) The system must fit into the integration envelope for the present CTB . 6) The system must be inexpensive STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  8. The Multi-Gap Resistive Plate Chamber MRPC is a good choice First suggested by C. Williams et al for ALICE TOF Uniform High Electric Field ~11kV/mm high drift velocity ~220m/ns high Townsend coefficient. Operate in Avalanche mode Gas: Freon (electron affinity ) iso-butane (UV photon absorption) SF6 (streamer suppressing) Heavy gas: 9-10clusters/mm for MIP Small gap: 0.2-0.3 mm, high resolution Multi-gaps: high efficiency E. Gorini et al. Nucl. Instr. Meth. A 396(1997), 93 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  9. MRPC R&D • Single pad MRPC • 4×4 cm2 • 5×0.22mm gas gap b) 12-pads MRPC 7×20cm2 6×0.25mm gas gaps pad size: 3.1×3 cm2 c) 6-pads 7×21cm2 10×0.25mm gas gaps pad size: 6×3.1cm2 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  10. Beam Test Results Cheng Li et al., NST, V13N1 Single pad, 5 gaps Efficiency:Time resolution: >~95% (6 gaps)~70ps (5 gaps) ~99% (2×5 gaps)~60ps (6 gaps) ~50ps (2×5 gaps) Counting rates range :< 500Hz/cm2(with normal float glass) STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  11. A prototype at STAR (2002+) 24 out of 28 modules made in USTC, China Covers 6 in azimuth and 1 in pseudo-rapidity,at radius ~ 2.2 m 1/120 of total coverage Module: 20×6 cm Gap：6×0.22 mm Pad：3.15cm×6.1cm Gas：95% C2H2F4 +5% Iso-C4H10 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  12. Timing Resolution before Calibration Resolution = 124 ps Calibration is necessary STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  13. Electronics (2005+) 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 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  14. 2.7 0.9 HPTDC INL Correction Integral Non-Linearity DifferentialNon-Linearity Jing Liu STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  15. t TDC TOT Time-TOT Correlation Leading-edge discrimination : timing signal (TDC) Trailing-edge discrimination: signal width (TOT) • Pulse with different amplitude give different timing (TDC) • TDC is correlated with TOT STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  16. beam Scan area Signal output Hit Position Correction propagation speed：~45ps/cm STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  17. 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 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  18. 2005 Cu+Cu, 62 GeV 2005 Cu+Cu, 200 GeV 2008 p+p, 200 GeV 2009 p+p, 500 GeV TOF Timing Resolution STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  19. TOF Time Resolution Summary STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  20. Hadron PID TPC alone: /k ~0.7 GeV/c, (,k)/p ~1.1 GeV/c TPC p K π TOF e TOF alone:  /k ~1.6 GeV/c, (,k)/p ~ 3.0 GeV/c STAR Collaboration, PLB 616 (2005) 8 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  21. Au+Au TPC only p+p With ONE TOF Prototype STAR, PLB 616, 8 (2005); PRL 97, 152301 (2006) Light hadron with TOF STAR PRL92,112301 (2004) STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  22. Light hadron with more coverage Fang Guo 500 GeV p+p ~75% TOF installed ~2 M events for these plots Statistics enhanced a lot TPC not well calibrated STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  23. |1/β-1|<0.03 Electron and muon ID Electron: pT>0.2 GeV/c Muon: pT<0.25 GeV/c STAR, PRL 94, 062301, (2005) arXiv: 0805.0364 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  24. Heavy Flavor with TOF D0Kp m e arXiv: 0805.0364 Very helpful for open charm and hidden charm physics STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  25. Light Nuclei with TOF Haidong Liu (STAR Collaboration), JPG 34, S1087 (2006), QM2006 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  26. Resonance with TOF Au+Au 200GeV Only one TOF track Enhanced by a factor of ~4 Yichun Xu et al., NIM A596, 186 (2008) Enhanced by a factor of ~2 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  27. Resanance with two TOF tracks Yanfei Shen S/B: K* ~0.12 f: ~3.2 500 GeV p+p ~75% TOF installed ~2 M events for these plots TPC not well calibrated STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  28. Summary and Outlook • The Advantage of MRPC-TOF: • good timing resolution (<80 ps) • high efficiency (>90%) • cost effective for large area TOF system • A prototype of TOF in STAR works very well: • Satisfied all of the requirements • Very helpful for identifying hadrons, leptons, light nuclei and resonances, achieved lots of important physics results. • We did good jobs: Detector R&D, mass production, calibration, software, physics analyses • 75% has been installed in STAR, 100% in 2010 Are we ready for the full TOF? STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  29. Extra slides STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  30. TOF-related physics (3M 500 GeV p+p ) • Identified particle spectra (pion, kaon, proton) • Resonance (K*, f etc) • Heavy Flavor • Electron • Muon • Charmonia (di-electron and hadronic channels) • Vector mesons through di-electron channel • Strangeness (V0) • Low pT (TOF of V0 constraint) • Intermediate and high pT STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  31. Start Detector -VPD W.J. Llope Collision Point • All hits in the same event arrived at the same time • As reference for each other VPD PMTs STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  32. 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) STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  33. T0 resolution w/o start detector – from data Run V 62.4 GeV CuCu After 6-round calibration iteration STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

  34. 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 STAR-TOF, Weihai Workshop, Weihai, Shandong, Aug. 13, 2009

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