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BRAHMS Y2000 run @ RHIC: s nn =130 GEV

BRAHMS Y2000 run @ RHIC: s nn =130 GEV. Reaction features in 65 AGeV Au + 65AGeV Au Electromagnetic dissociation dN(ch)/d  distribution -4<<4 vs. Collision Centrality Production of charged particles, N(ch)/pr.participant

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BRAHMS Y2000 run @ RHIC: s nn =130 GEV

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  1. BRAHMS Y2000 run @ RHIC: snn=130 GEV • Reaction features in 65 AGeV Au + 65AGeV Au • Electromagnetic dissociation • dN(ch)/d distribution -4<<4 vs. Collision Centrality • Production of charged particles, N(ch)/pr.participant • Bjorken limit attained ? Transparency or Stopping • p-bar/p vs y, b, pt • Strangeness vs y • Future… APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  2. BRAHMS Intl. collaboration I.G. Bearden7, D. Beavis1, C. Besliu10, Y. Blyakhman6, J. Bondorf7, J.Brzychczyk4, B. Budick6, H. Bøggild7, C. Chasman1, C. H. Christensen7, P. Christiansen7, J.Cibor4, R.Debbe1, J. J. Gaardhøje7, K. Grotowski4, K. Hagel8, O. Hansen7, H. Heiselberg7, A. Holm7, A.K. Holme12, H. Ito11, E. Jacobsen7, A. Jipa10, J. I. Jordre10, F. Jundt2, C. E. Jørgensen7, T. Keutgen9, 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.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. 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 APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  3. RHIC physicsAugust 2000 BRAHMS: Lpeak = 3.3  1025 cm-2 s-1 Lave = 1.7  1025 cm-2 s-1 Rcoll= 350 Hz 2:00 o’clock PHOBOS 10:00 o’clock RHIC PHENIX 8:00 o’clock 4:00 o’clock STAR 6:00 o’clock 6 b-1 9 GeV/u Q = +79 U-line BAF (NASA) m g-2 LINAC BOOSTER 2 wks HEP/NP AGS 1 MeV/u Q = +32 TANDEMS APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  4. BRAHMS in the 2’ hall … in 1998 APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  5. Forward & Midrapidity spectrometers MRS:2 TPC, 1 Dipole, 1TOF 30 - 90 deg. = 0 - 1.5 FS:2 TPC, 2 TOF, C, 3 Drift Ch. Mod., RICH, 4 Dipoles 2.5 - 30 deg.  = 1.5 - 4 APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  6. BRAHMS acceptanceAugust 2000 APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  7. Global detectorsSiMA, TMA, BB 97% (geom)  SiMA (2.0< | |<2.0)  PTMA (2.2< || <2.2)  Beam-Beam (3 < | | < 4) APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  8. Centrality determinationVertex distribution 1m APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  9. Electromagnetic nuclear dissociation n n 1n EM dissociation selected by ZDC coincidences and TMA Veto in BRAHMS n LO+NLO Mutual EM NLO • Mutual Electromagnetic dissociation • (Spectrum of virtual photons) * (absorption cross section) = WW • Multiphonon GDR excitation, abs • EM vs Nuclear coll. • => neutron (L*R) coincidences • RELDIS. Pshenichnov et al. 2n LO APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  10. Neutral Energy correlations (ZDC) C2(EL,ER)=P(EL,ER)/(P(EL)*P(ER)) APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  11. dNch/dSiMA, TMA, BB, TPC • N=dE /<dE> • P(0)/P(n1) • Background corr.due to secondaries (20-50%) • Consistency between several independent. detector systems •  N(ch)d= 4000±200 • Central 0-5% dN(ch)/d (=0) =550 • FWHM of distribution = 7.6  0.7 BRAHMS preliminary MTPC1 (CEJ) Yuri Blyakhman. BRAHMS Thesis APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  12. TPC tracks, Vertex reconstruction, Charged particle track density y z MTPC1 APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  13. Multiplicity of Charged Particle tracks in TPC’s B = 0 APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  14. 4000 charged part. observed Nch  23.5 pr. part. Pair cf. Nch  17 in p+p at s=130GeV 35-40% increase over p+p Total production of Charged particles ? Syst APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  15. Centrality and Number of Participants APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  16. NCharged vs. number of participant nucleon pairs FRITIOF EKRT HIJING 2 MTPC1 CEJ Claus Ekman Jørgensen. BRAHMSThesis 2 • dN/d 3 (=0) pr.part pair. • Cf. HIJING, FRITIOF • No saturation effects observed 2 APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  17. Hadron identification MRS (90, 40 deg)  K p 0  K± p-bar =3 p, pbar =0 p K  m2=p2( t2 / L2 -1) APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  18. Hadron IdentificationFS (4 deg)  =3 p-bar C1,H1,T2 m2=p2( t2 / L2 -1) + p p K+ + APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  19. N(pbar)/N(p)Centrality and Pt dependence • Antiproton absorbtion correction to pbar/p ratio: 5 % for FS at 4 deg 2 % for MRS at 90, 40 deg • 10% corr. (low pt) p from Be-tube • Applied to data • Most pbar and p from Hyperon decays fall into spectrometer acceptance. • Correction factor depends on H/B, H-bar/B-bar and TB/TH For H/B < 0.5 systematic correction is <  5% on ratio • Model dependent  not applied to data APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  20. Bjorken limit reached for Au+Au s= 130AGeV? ISR R803 s=63 s=23 BRAHMS-RHIC Subm. to PRL APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  21. P-bar/p ratioCentrality dependence BRAHMS APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  22. N(p-bar)/N(p) systematics vs CM energy BRAHMS STAR PHENIX  APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  23. N(pbar)/N(p)Au+Au s= 130AGeV BRAHMS Subm. to PRL APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  24. StrangenessK-/K+ vs rapidity CERN-SPS Preliminary APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  25. How consistent are the models? APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

  26. FUTURE RHIC startup June 2001 Au+Au s=200 AGeV Higher Luminosity Narrower vertex distribution p + p running BRAHMS full forward spectrometer ready Start full scan =0 to =4 High pt coverage (PID in FS to p=25 GeV/c) RESULTS Nch (0-5%)  4000 dN/d (y=0)  550. FWHM  7.6 N(ch)  23 pr. participant-pair dN/d (y=0)  3 pr. part. Pair AntiMeson/Meson close to unity p-bar/ p vs y shows increased but still incomplete transparency Midrapidity Plateau? y =0,0.7,2 : pbar/p  0.64, 0.66, 0.41 (±0.05 ± 0.06) Weak pt and centrality dependence Bjorken limit not reached Models inconsistent with data Summary First Au+Au s=130 AGeV APS-Wash-DC, Jens Jørgen Gaardhøje, Niels Bohr Institute

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