Centrality Dependence of  0 Production in Au+Au Collisions at = 62.4 GeV Stefan Bathe (UCR) for the PHENIX collaboration DNP Fall Meeting, October 2004

DNP04Stefan Bathe, PHENIX2 Hard Scattering and R AA Hard processes –yield scales with N coll –reason: small cross section incoherent superposition Nuclear Modification Factor R AA In the absence of nuclear effects: R AA =1 at high p T no effect strong suppression

DNP04Stefan Bathe, PHENIX3 Strong suppression at 130 and 200 GeV No suppression at 17 GeV  0 R AA, Central Events,Different √s 62.4 GeV Au+Au WA98, EPJ C 23, 225 (2002) [ new reference compiled by: D.d'Enterria nucl-ex/ ] PHENIX, PRL 88, (2002) Energy loss predicted to be proportional to –system size –gluon density changing  s –changing gluon density –changing expected energy loss –test of jet-quenching theory Why 62.4 GeV? –Between SPS and RHIC on logarithmic scale of √s –Wealth of p+p reference data 200 GeV: new preliminary result to higher p T

DNP04Stefan Bathe, PHENIX GeV p+p  0 Reference +/-25% uncertainty  0 data from ISR Corrected for (when necessary) –hadronic decay –direct photons Global fit: Fit and data cross- checked by NLO calculation ±25% systematic uncertainty

DNP04Stefan Bathe, PHENIX5    PHENIX Setup Central spectrometer arms |  | < 0.35 –  0 via  0  Lead scintillator calorimeter (PbSc) Lead glass calorimeter (PbGl)

DNP04Stefan Bathe, PHENIX6  0 Spectra at 62.4 GeV  0 data in min. bias, 0-10%, and 10-30%, and 30-60% most central collisions up to p T = 7GeV/c Small systematic uncertainty : 9~12%

DNP04Stefan Bathe, PHENIX7 R AA for  0 at 62.4 GeV Ratios close to unity at p T ~ 2.5 GeV/c, then decreasing Same tendency as 200 GeV Au+Au Less suppression at intermediate p T (compared to 200 GeV) N coll for peripheral events not yet understood

DNP04Stefan Bathe, PHENIX8 I. Vitev nucl-th/ Adil & Gyulassy nucl-th/ R AA (π 0 ) ~ Predictions for R AA at 62.4 GeV

DNP04Stefan Bathe, PHENIX9 R AA for  0 at 62.4 GeV Vitev nucl-th/ Reasonably good agreement (esp. high p T ) within uncertainties Uncertainty in the p T shape (esp. low p T ) of p+p reference...

DNP04Stefan Bathe, PHENIX10 R AA for  0 at 62.4 GeV charged reference with h/  ratio used here (cf. talk by J. Jia, CB 4) Agreement with charged reference better: Better p+p reference needed Vitev nucl-th/

DNP04Stefan Bathe, PHENIX11 R AA for Charged Hadrons 00 charged 00 0-10% 10-30% charged reference is used here 62.4 GeV  0 yield is multiplied by 1.6 Discrepancy between charged and  0 Neutral pions more suppressed than h+/- at intermediate p T Large proton contribution up to at least 4GeV/c (cf. talk by T. Chujo, CB 6)

DNP04Stefan Bathe, PHENIX12  0 R AA, Central Events,Different √s WA98, EPJ C 23, 225 (2002) [ new reference compiled by D.d'Enterria nucl-ex/ ] PHENIX, PRL (2002) Suppression at 17 GeV and 62.4 GeV similar at medium p T 62.4 GeV expected lower Better reference needed!

DNP04Stefan Bathe, PHENIX13 Summary Suppression at 200 GeV established to higher p T  0 spectra at 62.4 GeV for three centrality classes R AA for 0-10% and 10-30% most central events Suppression at intermediate p T less than in 200 GeV, but similar to 17 GeV Suppression in agreement with energy-loss calculations  0 more suppressed than h +/- at intermediate p T Result strongly depends on reference Better reference needed!

DNP04Stefan Bathe, PHENIX14 USA Abilene Christian University, Abilene, TX Brookhaven National Laboratory, Upton, NY University of California - Riverside, Riverside, CA University of Colorado, Boulder, CO Columbia University, Nevis Laboratories, Irvington, NY Florida State University, Tallahassee, FL Florida Technical University, Melbourne, FL Georgia State University, Atlanta, GA University of Illinois Urbana Champaign, Urbana-Champaign, IL Iowa State University and Ames Laboratory, Ames, IA Los Alamos National Laboratory, Los Alamos, NM Lawrence Livermore National Laboratory, Livermore, CA University of New Mexico, Albuquerque, NM New Mexico State University, Las Cruces, NM Dept. of Chemistry, Stony Brook Univ., Stony Brook, NY Dept. Phys. and Astronomy, Stony Brook Univ., Stony Brook, NY Oak Ridge National Laboratory, Oak Ridge, TN University of Tennessee, Knoxville, TN Vanderbilt University, Nashville, TN Brazil University of São Paulo, São Paulo China Academia Sinica, Taipei, Taiwan China Institute of Atomic Energy, Beijing Peking University, Beijing France LPC, University de Clermont-Ferrand, Clermont-Ferrand Dapnia, CEA Saclay, Gif-sur-Yvette IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, Orsay LLR, Ecòle Polytechnique, CNRS-IN2P3, Palaiseau SUBATECH, Ecòle des Mines at Nantes, Nantes Germany University of Münster, Münster Hungary Central Research Institute for Physics (KFKI), Budapest Debrecen University, Debrecen Eötvös Loránd University (ELTE), Budapest India Banaras Hindu University, Banaras Bhabha Atomic Research Centre, Bombay Israel Weizmann Institute, Rehovot Japan Center for Nuclear Study, University of Tokyo, Tokyo Hiroshima University, Higashi-Hiroshima KEK, Institute for High Energy Physics, Tsukuba Kyoto University, Kyoto Nagasaki Institute of Applied Science, Nagasaki RIKEN, Institute for Physical and Chemical Research, Wako RIKEN-BNL Research Center, Upton, NY Rikkyo University, Tokyo, Japan Tokyo Institute of Technology, Tokyo University of Tsukuba, Tsukuba Waseda University, Tokyo S. Korea Cyclotron Application Laboratory, KAERI, Seoul Kangnung National University, Kangnung Korea University, Seoul Myong Ji University, Yongin City System Electronics Laboratory, Seoul Nat. University, Seoul Yonsei University, Seoul Russia Institute of High Energy Physics, Protovino Joint Institute for Nuclear Research, Dubna Kurchatov Institute, Moscow PNPI, St. Petersburg Nuclear Physics Institute, St. Petersburg St. Petersburg State Technical University, St. Petersburg Sweden Lund University, Lund 12 Countries; 58 Institutions; 480 Participants* *as of January 2004

DNP04Stefan Bathe, PHENIX15 Backup Slides

DNP04Stefan Bathe, PHENIX16 p/pi ratio

DNP04Stefan Bathe, PHENIX17 h/pi ratio