BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Hadron Production at RHIC-PHENIX Tatsuya Chujo (BNL) for the PHENIX Collaboration

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Space-time Evolution in Relativistic Heavy Ion Collisions Hadronization (Freeze-out) + Expansion Pre-equilibrium Thermalization QGP phase Mixed phase pK  e   Space (z) Time Au  etc.. jet Hadrons reflect the bulk property of created system and its evolution!

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Physics of Identified Hadron Hydro-dynamical collective expansion velocity ( . Thermal freeze-out temperature (T th ). Chemical freeze-out temperature and chemical potential (T ch,  B ) Jet quenching effect at high p T by parton energy loss in medium (dE/dx). Space-time evolution of the system p T spectra dN/dy High p T spectra Shed light on QGP formation at RHIC HBT correlation

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Outline 1.Experimental setup and PID by TOF. 2.Identified charged hadron spectra. –Spectra shape –Inverse slope parameter vs. centrality –Particle ratios 3.HBT  +  +,  -  - correlations. In this presentation, we present the recent preliminary results in Au+Au collisions, = 130 mid-rapidity |  | < 0.35, Measured at RHIC-PHENIX.

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo PHENIX Detector Setup Beam-Beam Counter (BBC) z vertex, start timing for TOF Time-of-Flight (TOF) stop timing measurement Drift Chamber (DC) momentum, flight path length Pad Chamber 1 (PC1) additional track z information to Dch In this analysis, we use

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Reality of PHENIX EAST ARM TOF WALL CENTRAL MAGNET + MUON ARM

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Particle Identification by TOF TOF – TOF expected [ns] Demonstrated clear PID by TOF Time-of-Flight resolution  TOF ~ ps 3/27/01) Flight path length : ~ 5m K/  separation : < 2 GeV/c p/K separation : < 4 GeV/c

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo PID Cut Criteria Proton K+K+ ++ m 2 [(GeV/c 2 ) 2 ] Charge * Momentum [GeV/c] P K+K+ K-K- ++ -- p All momentum (a.u.) w/o PID cut PID by m 2 vs. momentum space |m 2 measured - m 2 0 | < 2.5  m 2 Momentum cutoff

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Centrality Classes Dch raw multiplicity distributions CentralityParticipants 0-5% 347  15% 5-15% 271  15% 15-30% 178  15% 30-60% 76  15% 60-80% 19  60% 80-92% 5  60% Used correlation between BBC charge and ZDC energy to define centrality. Extracted N part based on Glauber model.

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Results : Minimum bias p T spectra PHENIX Preliminary (a.u.) particlep T range p GeV/c K GeV/c proton GeV/c pbar GeV/c pions yield ~ proton/pbar p T ~ 2 GeV/c. How m T spectra look like?  next slide

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Minimum bias m T spectra PHENIX Preliminary (X ) (a.u.) In 0.2 < m t – m 0 < 1.2 [GeV/c 2 ], spectra for all species scaled by single exp. function. Similar inverse slope for  and K. T proton > T    ~ 205  5 (stat.)  15 (sys.) MeV K  ~ 215  5 (stat.)  20 (sys.) MeV p, ~ 320  10 (stat.)  20 (sys.) MeV p Fitting results by single exp. function

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Centrality Dependence of m T Spectra for  + + 0-5 % 5-15% 15-30% 30-60% 60-80% PHENIX Preliminary (a.u.) -- PHENIX Preliminary (a.u.) Single exponential scaling at GeV in m t -m 0 (soft region). (power low shape in most peripheral event ?) T  (central 0-5%) ~ 210 MeV  5 (stat.)  15 (sys.) MeV. Applied same parameterization for kaons and (anti-) protons.

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Centrality dependence of m T slope Weak centrality dependence for T  and T K. Gradual rise of T proton and T pbar from peripheral to mid-central collisions. T   T K < T proton PHENIX Preliminary (fitted at <1.0 GeV/c 2 in m t -m 0 )

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Mass Dependence of T Intuitive explanation of mass dependence of T  t : Transverse expansion velocity Good agreement with Hydro+UrQMD (cascade model).  K p PHENIX Preliminary nucl-th/ S. A. Bass et al. PHENIX Preliminary * NOTE: fitted at <1.0 GeV/c 2 in m t -m 0

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Comparison with CERN Energy PHENIX Preliminary The slopes of pions and protons at RHIC are higher than that of Pb+Pb collisions at SPS. Large transverse RHIC than SPS? SPS data : NA44 (most central) NOTE: fitted at <1.0 GeV/c 2 in m t -m 0

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo K + /K - and pbar/p ratio vs. centrality No clear dependence as a function of centrality (N part ) in both K + /K - and pbar/p ratios. central = 1.29±0.07(stat) ±0.19(sys.) pbar/p = 0.54±0.01(stat.)±0.08(sys.) Systematic errors ~15% K + /K - pbar/p

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Beam Energy Dependence of ratios C+C Ni+Ni KaoS E866 Au+Au Si+Au S+S PHENIX preliminary NA44 Pb+Pb PHENIX preliminary E866 Au+Au NA44 Pb+Pb pbar/p K + /K - pbar/p SIS AGS SPS RHIC K + /K Both ratios are closing to 1.0 from AGS, SPS to RHIC energy.

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo RHIC data point in  B -T plane Statistical thermal model hep-ph/ F.Becattini et al. Baryon chemical potential ~ 50MeV, not baryon free(  B =0). PHENIX preliminary RHIC (PHENIX) ?

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo HBT correlations Extraction of source size “R” using quantum interferometry 1/R C2C2   Particle emitting source x1x1 x2x2 p1p1 p2p2 X1’X1’ X2’X2’ R Assume Gaussian r eff with width “R” Correlation function C 2 Fourier transform of  eff →

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo 3D HBT measurement in PHENIX ~ q Tside ~ q Tout q long Full analytic coulomb corrections. Taking account two track separations. Minimum-bias data sample. Bertsch-Pratt parameterization

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Bertsch-Pratt Fit Results (TOF PID) R long = 6.7  0.9 R Tside = 5.8  1.5 R Tout = 5.49  0.54 =  R long = 4.0  1.2 R Tside = 7.9  1.1 R Tout = 6.23  0.54  =  ++ ++ -- --

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Beam energy dependence of R No indication of large volume  No big jump from SPS to RHIC Due to …. – High expansion velocities? ( i.e. x-p correlation) – Resonance contributions? AGS SPS RHIC Star Preliminary NA44 NA49 E866 E895 PHENIX Preliminary

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo Conclusions from Year-1 data Single particle spectra for  , K , protons and anti-protons in each centrality class and 2  HBT correlations are studied. Weak centrality dependence of slopes for T  and T K. Gradual rise of T proton and T pbar from peripheral to mid-central collisions. T   T K < T proton at all centrality classes. The slope of pions and protons at RHIC are higher than that of Pb+Pb collisions at SPS (indicative of large expansion RHIC). Weak centrality dependence in both K + /K - (~1.29) and pbar/p (~0.54). Baryon chemical potential ~ 50MeV (thermal model), not baryon free(  B =0). No indication of large source size in 2  HBT measurement. Start next data taking from May 2001!  ~1000 data will come soon, and more physics

BNL/ Tatsuya CHUJO JPS RHIC symposium, Chuo Univ., Tokyo See also 28aSG7 : Measurement of hadron spectra at RHIC-PHENIX experiment M. Suzuki (Univ. of Tsukuba) 28aSG8 : Study of charged particle ratios at RHIC-PHENIX experiment A. Kiyomichi (Univ. of Tsukuba)