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

2. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. What is PHENIX? PHENIX = Pioneering High Energy Nuclear Interaction eXperiment A large, multi-purpose nuclear physics experiment at the Relativistic Heavy-Ion Collider (RHIC)

3. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. A world-wide collaboration of  500 physicists from 51 Institutions in 12 countries The PHENIX collaboration

4. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. The PHENIX detector 2 Central Tracking arms 2 Muon arms Beam-beam counters Zero-degree calorimeters (not seen)

5. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. Charged particle tracking: Drift chamber Pad chambers (MWPC) Particle ID: Time-of-flight (hadrons) Ring Imaging Cherenkov (electrons) EMCal ( ,  0  ) Time Expansion Chamber

6. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. Example of a central Au+Au event at  s nn =200 GeV

7. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. 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 3 Tracking stations - cathode strip chambers 5 Id planes - Iarocci (streamer) tubes + 90 cm steel

8. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. Centrality Definition Centrality  impact parameter Two measures: Np : Number of participating nucleons N coll : Number of binary (nucleon- nucleon) collisions

9. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. Centrality Determinartion

10. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. 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 Multiplicity How many particles are produced (at mid-rapidity)? How does the multiplicity scale with centrality, N p or N coll ? B=0 Experimental Method

11. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. 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. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. 200 GeV130 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 Multiplicity at  s=200 GeV

13. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. PHENIX preliminary 200GeV/130GeV Stronger increase in Hijing than in data for central collisions Multiplicity ratio (200/130) GeV

14. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. Variation with  s nn To guide the eye

15. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. Hadron Identification with ToF Combining the momentum information with the flight-time: ,K separation p T < 2 GeV/c p,K separation p T < 4 GeV/c

16. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. 0 – 5 % 5 -10 % 10- 15 % 15 – 20 % 20 – 30 % 30 – 40 % 40 – 50 % 50 – 60 % 60 – 70 % 70 – 80 % 80 – 93 % Au+Au at  s = 200 GeV PHENIX preliminary Spectra, spectra, spectra… Centrality

17. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. deuterons and anti-deuterons where p d =2p p and B 2 is the coalescence parameter, B 2  1/V. Assuming that n and p have similar d 3 N/dp 3 Yield approximately exp. in mT.

18. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003.  0  Identification with EmCal Background subtracted Original spectrum

19. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. K. Adcox et al. (PHENIX Collaboration) Phys. Rev. Lett. 88(2002)022301 Suppressed  0 yield at high p T A remarkable observation: Yield above p T  2 GeV/c scales with N coll in peri- pheral collisions but is suppressed in central collisions!

20. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. The ratio R AA Quantify the deviation from binary scaling through R AA : 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. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. How do protons scale? proton yield/ for different centralities

22. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. proton/pion ratio p/   1 for p T > 2 GeV/c

23. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. |  |  0.35, 0.3  p T  2.0 GeV/c,  =  /2 Event-by-event fluctuations Study fluctuations in Q=n + – n – and Event-by-event

24. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. v(Q) as a function of collision centrality 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. |  |  0.35,  =  /2, 0.3  p T  2.0 GeV/c

25. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. * AuAu 200 GeV Preliminary o AuAu 130 GeV PHENIX PRC 66 (2002)024901 Maximum for semi- central collisions. F pT related to  T : PHENIX Preliminary F pT (%) Event-by-event fluctuations

26. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. J/   +  –, e + e – Run 2: Central tracking arm(e + e – ) + North muon arm (  +  – )

27. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003.   (pp->J/  ) = 3.8 + 0.6 (stat) + 1.3 (sys)  b Results pp  J/  + X

28. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. Magnet Muon Identifiers Muon 12.5° 35°35° 10.5° 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 < x 2 < 1.7 · 10 -1 1.1 · 10 -2 < x 2 < 2.2 · 10 -2 1.7 · 10 -3 < x 2 < 4.9 · 10 -3 cc mainly produced through gluon-gluon fusion North Central South

29. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. J/  in North arm, x Au  10 -3 J/  in Central arm, x Au  10 -2 J/  in South arm, x Au  10 -1 S Au N d J/  production in d+Au will be sensitive to shadowing in the Au-nucleus: Shadowing Eskola, Kolhinen, Vogt Nucl.Phys. A696 (2001) 729-746

30. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. First look at data from d+Au M inv North South Note: N/S not normalized to the same number of events

31. J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 2003. Conclusions Nearly logarithmic increase in multiplicity per participant with  s AGS  SPS  RHIC  yield suppressed at high p T proton yield not suppressed at high p T (binary scaling) J/  measured with muon and central arms J/  seen in d+Au data. Important baseline for AuAu; shadowing in Au. A lot of new exciting data (only a fraction was shown in this talk)