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Recent results from PHENIX at RHIC

Recent results from PHENIX at RHIC. Joakim Nystrand Lund University / University of Bergen. 10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. The PHENIX experiment Charged particle multiplicity p T spectra of hadrons at mid-rapidity

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Recent results from PHENIX at RHIC

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  1. Recent results from PHENIX at RHIC Joakim Nystrand Lund University / University of Bergen 10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. • The PHENIX experiment • Charged particle multiplicity • pT spectra of hadrons at mid-rapidity • Fluctuations (charged particle and pT) • J/e+e–, +–

  2. A large, multi-purpose nuclear physics experiment at the Relativistic Heavy-Ion Collider (RHIC) What is PHENIX? PHENIX= Pioneering High Energy Nuclear Interaction eXperiment

  3. The PHENIX collaboration A world-wide collaboration of  500 physicists from 51 Institutions in 12 countries

  4. 2 Central Tracking arms 2 Muon arms Beam-beam counters Zero-degree calorimeters (not seen) The PHENIX detector

  5. Charged particle tracking: • Drift chamber • Pad chambers (MWPC) • Particle ID: • Time-of-flight (hadrons) • Ring Imaging Cherenkov • (electrons) • EMCal (, 0) • Time Expansion Chamber

  6. Example of a central Au+Au event at snn =200 GeV

  7. 3 Tracking stations - cathode strip chambers 5 Id planes - Iarocci (streamer) tubes + 90 cm steel Muon tracking and identification South arm installed for Run2 (01-02) Au+Au, p+p North arm installed for Run3 (ongoing) d+Au, p+p

  8. Centrality Definition Centrality  impact parameter Two measures: Np : Number of participating nucleons Ncoll : Number of binary (nucleon-nucleon) collisions

  9. Centrality Determinartion

  10. B=0 Experimental Method Multiplicity How many particles are produced (at mid-rapidity)? How does the multiplicity scale with centrality, Np or Ncoll? • Combine the hits in PC1 and PC3. • The result is a sum of true combinations (from real tracks) and combinatorial background. • Determine the combinatorial background by event mixing

  11. Multiplicity per 2 participants HIJING X.N.Wang and M.Gyulassy, PRL 86, 3498 (2001) EKRT K.J.Eskola et al, Nucl Phys. B570, 379 and Phys.Lett. B 497, 39 (2001) K. Adcox et al. (PHENIX Collaboration), Phys. Rev. Lett. 86(2001)3500

  12. Multiplicity at s=200 GeV 130 GeV 200 GeV HIJING X.N.Wang and M.Gyulassy, PRL 86, 3498 (2001) Mini-jet S.Li and X.W.Wang Phys.Lett.B527:85-91 (2002) EKRT K.J.Eskola et al, Nucl Phys. B570, 379 and Phys.Lett. B 497, 39 (2001) KLN D.Kharzeev and M. Nardi, Phys.Lett. B503, 121 (2001) D.Kharzeev and E.Levin, Phys.Lett. B523, 79 (2001) PHENIX preliminary

  13. Multiplicity ratio (200/130) GeV 200GeV/130GeV PHENIX preliminary Stronger increase in Hijing than in data for central collisions

  14. To guide the eye Variation with snn

  15. Combining the momentum information with the flight-time: Hadron Identification with ToF ,K separation pT < 2 GeV/c p,K separation pT < 4 GeV/c

  16. Spectra, spectra, spectra… Au+Au at s = 200 GeV PHENIX preliminary Centrality 0 – 5 % 5 -10 % 10- 15 % 15 – 20 % 20 – 30 % 30 – 40 % 40 – 50 % 50 – 60 % 60 – 70 % 70 – 80 % 80 – 93 %

  17. Yield approximately exp. in mT. where pd=2pp and B2 is the coalescence parameter, B2 1/V. Assuming that n and p have similar d3N/dp3 deuterons and anti-deuterons

  18. Original spectrum Background subtracted 0 Identification with EmCal

  19. Suppressed 0 yield at high pT A remarkable observation: Yield above pT 2 GeV/c scales with Ncoll in peri- pheral collisions but is suppressed in central collisions! K. Adcox et al. (PHENIX Collaboration) Phys. Rev. Lett. 88(2002)022301

  20. The ratio RAA Quantify the deviation from binary scaling through RAA: Au+Au 200 GeV S.S. Adler et al. (PHENIX Collaboration) nucl-ex/0304022, submitted to PRL. p+p 200 GeV S.S. Adler et al. (PHENIX Collaboration) hep-ex/0304038, submitted to PRL.

  21. How do protons scale? proton yield/<binary collisions> for different centralities

  22. proton/pion ratio p/  1 for pT > 2 GeV/c

  23. Event-by-event fluctuations ||  0.35, 0.3  pT  2.0 GeV/c, =/2 Study fluctuations in Q=n+ – n– and Event-by-event <pT>

  24. v(Q) as a function of collision centrality ||  0.35, =/2, 0.3  pT  2.0 GeV/c A small deviation from stochastic emission observed at 130 GeV K. Adcox et al. (PHENIX) PRL 89(2002)082301 No dramatic change at 200 GeV - the upward shift of 0.01 units can be explained by harder track quality cuts leading to a reduced acceptance.

  25. Event-by-event fluctuations * AuAu 200 GeV Preliminary o AuAu 130 GeV PHENIX PRC 66 (2002)024901 Maximum for semi- central collisions. FpT related to T: PHENIX Preliminary FpT (%)

  26. J/ +– , e+e– Run 2: Central tracking arm(e+e–) + North muon arm (+–)

  27. Results pp  J/ + X s (pp->J/Y) = 3.8 + 0.6 (stat) + 1.3 (sys) mb

  28. cc mainly produced through gluon-gluon fusion 35° 35° Muon 12.5° 10.5° Magnet Muon Identifiers North CentralSouth Run 3 (d+Au, p+p): Both muon arms + Central arm South: –2.21< <–1.15 Central: –0.35< <0.35 North: 1.15 < <2.39 4.9 · 10-2 < x2 < 1.7 · 10-1 1.1 · 10-2 < x2 < 2.2 · 10-2 1.7 · 10-3 < x2 < 4.9 · 10-3

  29. Au S d N Shadowing J/ production in d+Au will be sensitive to shadowing in the Au-nucleus: J/ in North arm, xAu 10-3 J/ in Central arm, xAu  10-2 J/ in South arm, xAu  10-1 Eskola, Kolhinen, Vogt Nucl.Phys. A696 (2001) 729-746

  30. First look at data from d+Au North South Minv Minv Note: N/S not normalized to the same number of events

  31. Conclusions A lot of new exciting data (only a fraction was shown in this talk) • Nearly logarithmic increase in multiplicity per participant with s AGS  SPS  RHIC •  yield suppressed at high pT • proton yield not suppressed at high pT (binary scaling) • J/ measured with muon and central arms • J/ seen in d+Au data. Important baseline for AuAu; shadowing in Au.

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