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.
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, What is PHENIX? PHENIX = Pioneering High Energy Nuclear Interaction eXperiment A large, multi-purpose nuclear physics experiment at the Relativistic Heavy-Ion Collider (RHIC)
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, A world-wide collaboration of 500 physicists from 51 Institutions in 12 countries The PHENIX collaboration
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, The PHENIX detector 2 Central Tracking arms 2 Muon arms Beam-beam counters Zero-degree calorimeters (not seen)
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, Charged particle tracking: Drift chamber Pad chambers (MWPC) Particle ID: Time-of-flight (hadrons) Ring Imaging Cherenkov (electrons) EMCal ( , 0 ) Time Expansion Chamber
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, Example of a central Au+Au event at s nn =200 GeV
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, Centrality Definition Centrality impact parameter Two measures: Np : Number of participating nucleons N coll : Number of binary (nucleon- nucleon) collisions
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, Centrality Determinartion
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, PHENIX preliminary 200GeV/130GeV Stronger increase in Hijing than in data for central collisions Multiplicity ratio (200/130) GeV
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, Variation with s nn To guide the eye
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, – 5 % % % 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
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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.
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 0 Identification with EmCal Background subtracted Original spectrum
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, K. Adcox et al. (PHENIX Collaboration) Phys. Rev. Lett. 88(2002) 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!
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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/ , submitted to PRL. p+p 200 GeV S.S. Adler et al. (PHENIX Collaboration) hep-ex/ , submitted to PRL.
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, How do protons scale? proton yield/ for different centralities
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, proton/pion ratio p/ 1 for p T > 2 GeV/c
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, | | 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
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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) 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
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, * AuAu 200 GeV Preliminary o AuAu 130 GeV PHENIX PRC 66 (2002) Maximum for semi- central collisions. F pT related to T : PHENIX Preliminary F pT (%) Event-by-event fluctuations
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, J/ + –, e + e – Run 2: Central tracking arm(e + e – ) + North muon arm ( + – )
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, (pp->J/ ) = (stat) (sys) b Results pp J/ + X
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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 < < · < x 2 < 1.7 · · < x 2 < 2.2 · · < x 2 < 4.9 · cc mainly produced through gluon-gluon fusion North Central South
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, J/ in North arm, x Au J/ in Central arm, x Au J/ in South arm, x Au 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)
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, First look at data from d+Au M inv North South Note: N/S not normalized to the same number of events
J. Nystrand, Lund/Bergen10th Nordic Meeting on Nuclear Physics, Oslo, May 12-16, 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)