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The Time-Of-Flight Detector for RHIC/STAR and Related Physics. Jian WU University of Science & Technology of China. Outline Introduction MRPC & Performance of TOF prototypes Physics results Summary and outlook. 2SC. Introduction Heavy Ion Collisions – search for QGP. Tc~160MeV
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The Time-Of-Flight Detector for RHIC/STAR and Related Physics Jian WU University of Science & Technology of China Outline Introduction MRPC & Performance of TOF prototypes Physics results Summary and outlook ATHIC 2006 Seoul
2SC IntroductionHeavy Ion Collisions – search for QGP Tc~160MeV ε(Tc)~1GeV/fm3 ATHIC 2006 Seoul
BRAHMS PHOBOS STAR PHENIX IntroductionRelativistic Heavy Ion Collider (RHIC) ATHIC 2006 Seoul
IntroductionSolenoidalTrackerAtRHIC(STAR) ATHIC 2006 Seoul
IntroductionParticleIDentification@STAR Ionization Energy Loss (dE/dx) in TPC π/K 0.6 GeV/c proton/meson 1.0GeV/c ATHIC 2006 Seoul
IntroductionWhy TOF of MRPC ? Key measurements so far: • Collective flow • High pT suppression --- jet quenching • Number of constituent quark scaling of elliptic flow Stable particles, resonances, V0 particles etc. • Identified particle characteristics • High pT reach • High detecting efficiency New technology – MultigapResistivePlateChamberEconomic! ATHIC 2006 Seoul
IntroductionTOF requirement • Requirements about TOF detector for STAR • Good timing resolution (<100ps) • Small occupancy (~10%) • Large acceptance (|η|<1, ΔΦ~2π) • Greatly Extend PID capability of stable hadrons: pi/K ~ 1.8GeV, p/(pi+K) ~ 3GeV • Significantly reduce the integrated luminosity needed for the key measurements. • Extend the pT reach of resonances measurements. • Allow us to study large and small scale correlations and fluctuations. • ...... ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes E. Cerron Zeballos et al. Nucl. Instr. Meth. A 374, 132(1996) M.C.S. Williams et al. Nucl. Instr. Meth. A 478, 183(2002) ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes Sensitive area ~20 x 6.3 cm2 ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes Simulation of MRPC : Charge distributions M. Abbrescia et al., Nucl. Instr. and Meth. A 398 (1997) 173-179 Nucl. Instr. and Meth. A 431 (1999) 413-427 ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes Proto type of MRPC-TOF (TOFr) 241.3cm long, 21.6cm wide and 8.9cm high. 32 MRPC modules ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes Test of TOFr @AGS • gas : Freon 90% i-C4H10 5% SF6 5% • Efficiency > 95% • σt < 75 ps B. Bonner et al., Nucl. Instr. Meth. A 508, 181(2003) M. Shao et al., Nucl. Instr. Meth. A 492, 344(2002) ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes TOFr @STAR ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes TOF Starter: Pseudo-Vertex Position Detector • ±5.4m , 4.43<||<4.94, ~19% • Trigger Efficiency:100%,30%,10%in Au+Au,d+Au,p+p • t:25,85,140 psinAu+Au,d+Au,p+p(200 GeV) ATHIC 2006 Seoul
MRPC & Performance of TOF prototypes ATHIC 2006 Seoul
Physics results ATHIC 2006 Seoul
Physics results ATHIC 2006 Seoul
Summary and outlook • The advantages of new technology – MRPC: good timing resolution, high efficiency , low cost to enable large acceptance etc. • The prototype of TOF detector in STAR works well, and satisfies the requirements proposed. σt ~ 85 ps , efficiency ~ 95% • TOFr detector has already provided important physics results. ATHIC 2006 Seoul
Summary and outlook Physics with Full Barrel TOF - I Reduce the required integrated luminosity Open charm Resonances ATHIC 2006 Seoul
Summary and outlook Physics with Full Barrel TOF - II Vector meson study – benefit from the electron PID Total bkgd: ~10-4/25MeV (ω) ~2∙10-5/25MeV (Φ) Dalitz decay bkgd: ~5∙10-6/25MeV (ω) ~5∙10-7/25MeV (Φ) ATHIC 2006 Seoul
Summary and outlookPhysics with Full Barrel TOF - III ATHIC 2006 Seoul
Summary and outlook Project Schedule ATHIC 2006 Seoul
STAR TOF group STAR TOF Team: 16 institutions US Electronics, tray assembly and integration China Module construction andQA BNL, LBL, MEPI, NASA, UNAM, RICE, UCLA, UT-Austin, U. Washington, Yale Huazhong Normal University, IHEP(Beijing), IMP(Lanzhou), SINR, Tsinghua, USTC ATHIC 2006 Seoul
The End Thanks! ATHIC 2006 Seoul
Backup slides ATHIC 2006 Seoul
Today t = 51017 sec T=1 meV Quark-hadron transition Hadrons form - protons & neutrons t = 10-6 sec T=1 GeV The Planck epoch ATHIC 2006 Seoul
Specification of typical MRPC ATHIC 2006 Seoul
Avalanche Process Exponential Avalanche Avalanche Fluctuation Coefficient: The Signal Induced Process Ionization Process Weighting Field Cluster Numbers: Total Signal in One Gap: j-th Cluster Position: Working Principle Simulation ATHIC 2006 Seoul
W.J. Llope et al., nucl-ex/0308022 ATHIC 2006 Seoul
detecting efficiency: ~95%was achieved. ATHIC 2006 Seoul
Cronin Effect of Identified Particles • Enhancement above pT ~ 1-1.5 GeV/c • RdAu of protons increases faster than that of pions • Protons ~ not Nbin scaling in intermediate pT nucl-ex/0309012 ATHIC 2006 Seoul
Cronin Data at Lower energy J.W. Cronin et al., PRD 11, 3105 (1975); • Enhancement of hadron production in proton-nucleus collisions. • R=1 in absence of nuclear effects. • Bound nucleons “cooperate” producing high-pT particles. • Suppression at small pT. • Explained by initial multiple scattering. Cronin effect larger for protons compared to pions ATHIC 2006 Seoul
Proton/hadron ratio J.W. Cronin et al., PRD 11, 3105 (1975) P.B. Straub et al., PRL 68, 452 (1992) nucl-ex/0309012 • p-=0.041 0.010 0.006 (1.2 < pT < 3 GeV/c), lower energy sqrt(s)~30 GeV/c, p-=0.095 0.004 • (pbar+p)/h=0.24,a factor of 2 smaller than that in Au+Au AuAu baryon excess due to Final State Effect. ATHIC 2006 Seoul
nucl-ex/0407006 ATHIC 2006 Seoul
Physics with Full Barrel TOF - I Improve the V0 particle reconstruction significance Clearly identified daughters Outlook ATHIC 2006 Seoul