1. STAR Physics Program with the TOF Nu Xu for the STAR Collaboration Nuclear Science Division Lawrence Berkeley National Laboratory

2. Nu Xu2/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR STAR Physics Focus 1) At 200 GeV top energy - Study medium properties, EoS - pQCD in hot and dense medium 2) RHIC beam energy scan - Search for the QCD critical point - Chiral symmetry restoration Polarized spin program - Study proton intrinsic properties Forward program - Study low-x properties, search for CGC - Study elastic (inelastic) processes (pp2pp) - Investigate gluonic exchanges

3. Nu Xu3/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR STAR DetectorMRPC TOF barrel 100% ready for run 10 BBC PMD FPD FMSFMS EMC barrel EMC End Cap DAQ1000 FGT Completed Ongoing MTD R&D HFT TPC FHC HLT

4. Nu Xu4/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR STAR: Physics with TOF 1)Significant improvement in PID. With TPC, PID will be extended to p T ~ 15 GeV/c 2)Correlations with PID hadrons; resonances (up to Ω); trigger with high p T hadrons … 3) Beam energy scan program: event-by-event K/π analysis and net-proton Kurtosis 4)2π electron and di-electron analysis; heavy flavor program … STAR TOFSTAR TPC+TOF Log 10 (p)

5. Nu Xu5/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR red: with STAR TOF black: without STAR TOF Acceptance: 10-30 times larger compared with PHENIX Crucial for enhancing future heavy flavor measurements Transverse Momentum p T (GeV/c) J/Ψ  e + + e - reconstruction efficiency Heavy Flavor Efficiency Improvement

6. Nu Xu6/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR Current Measurements with J/Ψ (Run7 64M MB events) Run10, √s NN = 200 GeV Au+Au collisions: 1)Measure the v 2 of J/Ψ, with the help of HLT 2)Measure the R AA of J/Ψ at high transverse momentum p T > 5 GeV/c STAR submitted to PRL 0904.0439

7. Nu Xu7/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR STAR High Level Trigger and TOF Run9 p+p 200 GeV, May 19 - 25 J/ψ 1)Fast filtering for quick data analysis. Run10: try J/ψ v 2 2)Online QA 3)TOF: improve STAR trigger capabilities: vertex, pile-up rejection capability…

8. Nu Xu8/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR Low p T (≤ 2 GeV/c): hydrodynamic mass ordering High p T (> 2 GeV/c): number of quarks ordering s-quark hadron: smaller interaction strength in hadronic medium light- and s-quark hadrons: similar v 2 pattern => Collectivity developed at partonic stage! Partonic Collectivity at RHIC

9. Nu Xu9/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR Reconstruction Efficiency Improvement TOF: 1)Increase efficiency for all resonances 2)Extend the p T reach = EOS parameters: temperature and collective velocities

10. Nu Xu10/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR The di-Lepton Program at STAR (1) σ (2) v 2 (3) R AA Mass (GeV/c 2 ) p T (GeV/c) ρ ϕ J/ψ DY, charm Bk Chiral Symmetry Restoration Direct Radiation from The Hot/Dense Medium * TOF is Crucial for the physics. PHENIX: S. Afanasiev,, et al. 0706.30434

11. Nu Xu11/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR Direct Radiation Expanding partonic matter at RHIC and LHC! Di-leptons allow us to measure the direct radiation from the matter with medium effects, no hadronization! - Low mass region: , ,   e - e + m inv  e - e + medium effect Chiral symmetry - High mass region: J/   e - e + m inv  e - e + Direct radiation

12. Nu Xu12/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR Multi-particle Correlations in STAR -- evidence of conical emission STAR: PRL 102, 052302(2009) d+Au Au+Au central  1  2  0 0  Away-side trigger = STAR large acceptance for correlation analysis = Search for Mach cone with identified hadrons => Properties of the EoS

13. Nu Xu13/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR nuclei hadron gas CSC quark-gluon plasma TcTc Baryon Chemical Potential Critical Point? Temperature Early Universe 1 2 3 2 Density Frontier T E RHIC, FAIR 1 Energy Frontier T C LHC, RHIC 3 Baryon Density 1 st order pha. tran. FAIR, NICA RHIC Beam Energy Scan Program

14. Nu Xu14/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR Search for Local Parity Violation … L or B The separation between the same-charge and opposite- charge correlations. - Strong EM fields - De-confinement and Chiral symmetry restoration - PID LPV analysis with TOF - RHIC BES: disappearance

15. Nu Xu15/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR High Moment Analysis (BES) STAR Preliminary, QM09 1)High moments are more sensitive to critical point related fluctuations 2)The 4 th moment, Kurtosis, is directly related to the corresponding thermodynamic quantity: susceptibility for conserved quantum numbers such as Baryon number, charge, strangeness…

16. Nu Xu16/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR Particle Identification at STAR STAR TPC STAR TOF STAR EMC STAR HFT Neutral particles Strange Jets Heavy Quark hyperons Hadrons Multiple-fold correlations among the identified particles! e, μ π K p d TPC TOF TPC Log 10 (p)

17. Nu Xu17/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR HFT: Charm Hadron v 2 and R AA - 200 GeV Au+Au m.b. collisions (500M events). - Charm hadron collectivity  drag/diffusion constants  Medium properties! - 200 GeV Au+Au m.b. collisions (|y|<0.5 500M events) - Charm hadron R AA  - Energy loss mechanism! - QCD in dense medium!

18. Nu Xu18/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR HFT TPC FGT STAR Detectors: Full 2π particle identification! EMC+EEMC+FMS (-1 ≤  ≤ 4) TOF DAQ1000 HLT

19. Nu Xu19/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR TOF Operation and Data Analysis Operation Data Analysis BNL, RICE, UT, … Calibrations Reconstruction BNL, IOPP, LBNL, RICE, SINAP, Tsinghua, USTC, … BNL, KISTI STAR Physics Working Groups

20. Nu Xu20/20STAR-DOE TOF Review, BNL, August 10-11, 2009 STAR Summary TOF is a key upgrade at STAR. It greatly extends STAR’s PID capabilities for multiple physics topics, including: - Thermalization at RHIC - QCD phase boundary and critical point - In-medium properties - Study gluon-rich phenomena at RHIC STAR thanks DoE NP and NNSFC for their support!