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P t Spectra of Identified Hadrons Measured with the PHENIX experiment at RHIC

P t Spectra of Identified Hadrons Measured with the PHENIX experiment at RHIC. The detector Hadron identification Corrections to raw distributions M t and P t distributions - minimum bias and as a function of centrality T eff and < p t > versus N part.

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P t Spectra of Identified Hadrons Measured with the PHENIX experiment at RHIC

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  1. Pt Spectra of Identified Hadrons Measured with the PHENIX experiment at RHIC • The detector • Hadron identification • Corrections to raw distributions • Mt and Pt distributions - minimum bias and as a function of centrality • Teff and < pt > versus Npart Julia Velkovska, SUNY at Stony Brook, for the PHENIX collaboration Julia Velkovska , QM2001

  2. The PHENIX detector Hadron identification • drift chamber (DC) • Pad chamber 1 (PC1) • Time-of-flight (TOF) • Beam-beam counters (BBC) Julia Velkovska , QM2001

  3. PHENIX acceptance • Tracking D h = 0.8 D f = 180 deg • Time-of-flight D h = 0.7 D f = 45 deg -.4 -.2 0.2 .4 y Julia Velkovska , QM2001

  4. Hadron Identification • Tracking system: drift chamber , Pad chamber • momentum measurement • path length to TOF detector • Timing system • beam-beam counters - start time • Time-of-flight counters - stop time Julia Velkovska , QM2001

  5. Particle Id Cuts • PID bands defined in mass2 vs momentum space sms=0.60.1 mrad • K cut off at 1.6 GeV/c • p cut off at 2.2 GeV/c • protons - up to 5 GeV/c st = 1205 ps, sa=2.80.2 mrad, Julia Velkovska , QM2001

  6. Correctionsbased on single particle Monte Carlo p K p Overall scale • acceptance • dead areas • tracking efficiency decays Momentum resolution Multiplicity dependence- small: studied by track embedding into real events acceptance Julia Velkovska , QM2001

  7. Minimum Bias mt distributions Julia Velkovska , QM2001

  8. Minimum Bias mt distributions Fit ranges in pt : pions: 0.3 < pt < 1.0(GeV/c) kaons: 0.6 < pt < 1.0 (GeV/c) protons: 0.8 < pt < 2.2 (GeV/c) 0.8 < pt < 3 (GeV/c) anti-protons: 0.8 < pt < 2.2 (GeV/c) Julia Velkovska , QM2001

  9. Particle inverse slopes in minimum bias events • negative pions215 +/- 3 +/- 15 MeV kaons 225 +/- 15 +/- 20 MeV antiprotons 300 +/- 10 +/- 20 MeV • positive pions 210 +/- 3 +/- 15 MeV kaons 220 +/- 15 +/- 20 MeV protons 320 +/- 10 +/- 20 MeV • Teff = Tfo + m0 <bT>2 Julia Velkovska , QM2001

  10. Freeze-out T and flow velocity • RHIC Au+Au • Tfo= 186 +/- 18 MeV • <bt > = 0.36 +/- 0.05 • SPS Pb+Pb • Tfo = 149 +/- 22 MeV • <bt > = 0.39 +/- 0.04 Julia Velkovska , QM2001

  11. Centrality Selection • Centrality selection based on the correlation between beam-beam counters and ZDC counters • Number of tracks/event with these selections Julia Velkovska , QM2001

  12. Pion mt-distributions as a function of centrality Julia Velkovska , QM2001

  13. Inverse slope versus Npart 0 100 200 300 400 0 100 200 300 400 Julia Velkovska , QM2001

  14. Flow at RHIC and SPS in central events • PHENIX 15% CENTRAL p+ 212 +/-5 +/- 15 MeV p 332 +/-10 +/- 20 MeV • protons at SPS <(NA44+NA49)> 290 +/- 10 MeV Julia Velkovska , QM2001

  15. Comparison to theory : hydro + cascade Derek Teaney • Proton slopes are sensitive to the EOS • The PHENIX measurement has discriminatory power against various model assumptions Julia Velkovska , QM2001

  16. Transverse momentum distributions in minimum bias events • Large proton and anti-proton yield at high pt • Sort in centrality classes • In the entire pt range fit: powerlaw function top exponential- Kand p • extract <pt> from the fit Julia Velkovska , QM2001

  17. Mean pt versus number of participants • Pions steep rise and plateau • Protons gradual rise and higher <pt> Julia Velkovska , QM2001

  18. Conclusions • Measured p, K, pup to2.2/1.6/3.5 GeV/c in pt • Pion spectra nearly independent of Npart beyond the very peripheral collisions • Kaon inverse slopes are rather similar to those of pions • Protons/anti-protons inverse slopes rising with Npart • Proton inverse slopes higher than at SPS. • High pthadron yields dominated by protons/anti-protons Julia Velkovska , QM2001

  19. Charged hadron spectra • After normalizing the p- yield to p0 yield - sum all identified negative hadron spectra • Compare to non-identified h- spectra - very good agreement observed • Significant contribution of anti-protons above pt = 2 GeV/c Julia Velkovska , QM2001

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