1. Light Nuclei Spectra in STAR Run5 62GeV Cu+Cu Experiments Jianhang Zhou Rice University

2. 3/17/20071 Motivation 1)Light nuclei spectra are important for calculating coalescence parameter. D/Dbar, He3, and alpha spectra, B2 parameters, P/Pi ratios, are important to learn the physical features in the QGP freeze-out stage. 2) The spectra based on 200GeV Au+Au collisions have already been studied (by Haidong Liu). 3) This is an atempt to analyze the spectra based on 62GeV Cu+Cu collisions.

3. 3/17/20072 Data Used: RHIC STAR Run-5 data 62GeV Cu+Cu from : 1) Calibrated Time of Flight (TOF) data 2) TPC MuDst data

4. 3/17/20073 TPC(Time Projection Chamber) PID method: Ionization Energy Loss dE/dx STAR PID Capable Detectors: TPC and TOF TOF (Time of Flight) Structure: pVPD and TOF tray PID method: measure TOF=T(stop)-T(start), along with p from TPC, => calculate Mass

5. TOF PID: M^2 Distribution Cuts: |nσ_D| 4, 2.5<m^2<-4.5, -0.1<eta< -0.9. M^2 of Deuteron: fitted by a Gaussian, and then integral M^2 of Anti-D: Too few events, No fitting, just use number counts

6. 3/17/20075 TOF Spectra: P, Pbar, D, Dbar, Pi+, Pi- Match efficiency is fixed at 0.5%.

7. 3/17/20076 TPC PID: N-sigma Distribution Cut: |q|=1, refmult>=18, nHitsFit>=25,nHitsDedx>=15,dca<=1 N-sigma of Proton, For 0.2GeV<Pt<0.4GeV, Close to Gaussian Distribution N-sigma of Proton, For 0.7GeV<Pt<1.0GeV, Fit by Gaussian(particle) + Exponential(background)

8. 3/17/20077 N-Sigma of Deuteron for different Pt ranges: N-Sigma of Proton for different Pt ranges: histogram is fit by: Exponential +Gaussian

9. 3/17/20078 TPC Spectra: P, Pbar, D, Dbar, Pi+, Pi-

10. 3/17/20079 Comparison of spectra from TPC and TOF

11. 3/17/200710 Summary Attempts were made to study the spectra of P/Pbar, D/Dbar, Pion+/- of STAR run5 62GeV Cu+Cu data. The spectra of nuclei were plotted for based on TOF and TPC PID respectively. Two results are combined and compared. Further studies are in the plan: 1)Re-calculate match efficiency for TOF. 2)Low Pt absorption correction will be applied. 3)Coalescence parameter B2 will be calculated. 4)TPC data of different centrality will be studied separately. 5)Helium3 and alpha will also be studied. 6)All will be compared to 200GeV Au+Au results.