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High P T Measurements with BRAHMS

High P T Measurements with BRAHMS. I.G. Bearden, Niels Bohr Institute For The BRAHMS collaboration. The BRAHMS Collaboration. - 52 people from 12 institutions-. I.G. Bearden 7 , D. Beavis 1 , C. Besliu 10 , Y. Blyakhman 6 , J.Brzychczyk 4 , B. Budick 6 ,

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High P T Measurements with BRAHMS

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  1. High PT Measurements with BRAHMS I.G. Bearden, Niels Bohr Institute For The BRAHMS collaboration BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  2. The BRAHMS Collaboration - 52 people from 12 institutions- I.G. Bearden7, D. Beavis1, C. Besliu10, Y. Blyakhman6, J.Brzychczyk4, B. Budick6, H. Bøggild7 ,C. Chasman1, C. H. Christensen7, P. Christiansen7,J.Cibor4, R.Debbe1, J. J. Gaardhøje7,M. Germinario7,K. Grotowski4 , K. Hagel8, O. Hansen7, H. Ito11, E. Jacobsen7, A. Jipa10, J. I. Jordre10, F. Jundt2, C.E.Jørgensen7, E. J. Kim5, T. Kozik3, T.M.Larsen12, J. H. Lee1, Y. K.Lee5, G. Løvhøjden2, Z. Majka3, A. Makeev8, B. McBreen1, M. Murray8, J. Natowitz8, B. Neuman11,B.S.Nielsen7, K. Olchanski1, D. Ouerdane7, R.Planeta4, F. Rami2, D. Roehrich9, B. H. Samset12, S. J. Sanders11, I. S. Sgura10, R.A.Sheetz1, Z.Sosin3, P. Staszel7, T.S. Tveter12, F.Videbæk1, R. Wada8 and A.Wieloch3,Z. Yin9 1Brookhaven National Laboratory, USA, 2IReS and Université Louis Pasteur, Strasbourg, France 3Jagiellonian University, Cracow, Poland, 4Institute of Nuclear Physics, Cracow, Poland 5Johns Hopkins University, Baltimore, USA, 6New York University, USA 7Niels Bohr Institute, Blegdamsvej 17, University of Copenhagen, Denmark 8Texas A&M University, College Station. USA, 9University of Bergen, Norway 10University of Bucharest, Romania,11University of Kansas, Lawrence,USA 12 University of Oslo Norway BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  3. 95° h=0 30° 2.3° h=2 30° 15° The BRAHMS Experiment BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  4. Au+Au Charged Hadron Spectra h~2 h=0 BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  5. d+Au Charged Hadron Spectra 200GeV (BRAHMS preliminary) h=0 BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  6. Nuclear Modification Factor The nuclear modification factor: Glauber calculation • Hard processes (incoherent) • scaling with the number of binary collisions Nbin. BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  7. p+A: How does it look at lower energies? Central Pb+Pb (SPS): Modification quantified by: spA=Aa(pT)spp High pT enhancement explained by initial state multiple scattering (“Cronin effect”) and (for SPS) transverse flow… BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  8. (sNN=200 GeV) Reference Spectrum • UA1 acceptance |h| < 2.5 • STAR acceptance |h| < 0.5 • BRAHMS acceptance: • (this analysis) • MRS: |h| < 0.15 • FS: 2.0 <h < 2.2  scale UA1 results to BRAHMS acceptance. BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  9. BRAHMS preliminary BRAHMS preliminary Nuclear Modification h=0 Au+Au at 200GeV Central to “peripheral” (cancellation of systematic errors) • Large high pT suppression • for central collisions • Not seen for “peripheral” • collisions BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  10. BRAHMS preliminary BRAHMS preliminary Nuclear Modification h=2 Au+Au at 200GeV Central to “peripheral” (cancellation of systematic errors) • Qualitatively same behaviour as • seen at h=0 BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  11. BRAHMS preliminary BRAHMS preliminary Comparison h=0 to h=2 h=0 h=2 h=0 h=2 BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  12. d+Au Nuclear Modification h =0 High pT enhancement observed in d+Au collisions at sNN=200 GeV. • Comparing Au+Au to d+Au • strong effect of dense nuclear medium BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

  13. BRAHMS preliminary Au+Au, h=0 BRAHMS preliminary Au+Au, h2 BRAHMS preliminary d+Au, h=0 Summary • Au+Au at sNN=200 GeV, h=0: •  Strong high pT suppression • in central collisions •  Suppression not observed in semi-peripheral • collision (40-60%) • Strong effect of dense medium! • Au+Au at sNN=200 GeV, h2: • Similar behaviour as observed at h=0 • (calls for additional theoretical work) • Medium extends to h=2! • d+Au at sNN=200 GeV, h=0: • “Cronin” like enhancement • Medium not present in d+Au! BNL High Pt Colloquium I.G.Bearden, Niels Bohr Institute

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