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BRAHMS Y2000 + Y2001 @ RHIC: s nn =130 GeV, and s nn =200 GeV

BRAHMS Y2000 + Y2001 @ RHIC: s nn =130 GeV, and s nn =200 GeV. Reaction features in 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au-AU collisions EM dissociation dN(ch)/d  distribution -4<<4 vs. Collision Centrality

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BRAHMS Y2000 + Y2001 @ RHIC: s nn =130 GeV, and s nn =200 GeV

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  1. BRAHMS Y2000 + Y2001 @ RHIC: snn=130 GeV, and snn=200 GeV • Reaction features in 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au-AU collisions • EM 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 Paris, 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, Denmark8Texas A&M University, College Station. USA 9University of Bergen, Norway 10University of Bucharest, Romania 11University of Kansas, Lawrence,USA 12 University of Oslo Norway Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  3. RHIC physicsAugust 2000 & August 2001 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 August 2000 and 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  4. BRAHMS in the 2’ hall … in 1998 Paris, 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, C1-threshold,3 Drift Ch.Mod.,RICH, 4 Dipoles 2.5 - 30 deg.  = 1.5 - 4 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  6. First BRAHMS collision at 100 AGeV+100AGeV T2 FS: 6 deg 0.8 msr T1 MRS: 90 deg 6.5 msr MTPC1 MTPC2 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  7. BRAHMS acceptanceAugust 2000 & 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

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

  9. Centrality determinationVertex distribution 1m Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  10. 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, JPB, IM, et al. 2n LO Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  11. Neutral Energy correlations (ZDC) C2(EL,ER)=P(EL,ER)/(P(EL)*P(ER)) Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  12. dNch/d @ snn= 130 GeVSiMA, TMA, BB, TPC BRAHMS Subm. Phys. Lett. B 7/2001. • N=dE /<dE> • P(0)/P(n1) • Background corr.due to secondaries (37-50%) • Consistency between 4 independent detector systems • 65 AGeV+ 65 AGeV: •  N(ch)d= 4050±300 • Central 0-5% dN(ch)/d (=0) =550 • FWHM of distribution = 7.6  0.7 600 0-5% 5-10% 10-20% 20-30% 30-40% 40-50% Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  13. TPC tracks, Vertex reconstruction, Charged particle track density y z MTPC1 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  14. SPS Charged Particle Mult.snn=130 GeV BRAHMS. Subm. to Phys Lett. B. 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  15. NCharged vs. number of participant nucleon pairs. snn=130AGeV FRITIOF EKRT HIJING MTPC1 CEJ Claus Ekman Jørgensen. Thesis NBI 2001 • dN/d 3 (=0) pr.part pair. • Cf. HIJING, FRITIOF • No saturation effects observed Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  16. RHIC: 200 AGeVWill this happen? Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  17. dNch/d for100 AGeV + 100 AGeV • 100 AGeV + 100 AGeV Au+Au •  N(ch)d= 5100±300 • Central 0-6% dN(ch)/d (=0) =61050 • FWHM of distribution = 7.9  1.0 BRAHMS 200AGEV Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  18. Hard and Soft vs.High Density QCD @ 200 AGeV • Kharzeev and Levin (nucl-th/0108006) • Soft-Hard: dN/d=(1-X) npp <Npart>/2 + X npp <Ncoll> <Ncoll>=1049, <Npart>=339, npp=2.43=>dN/d=668 (with X=0.9) • High Density QCD-saturation: dN/dy = f( Npart, Qs2, ,QCD,s,y) with =0.3 from HERA data => dN/d=620 (using dN/d=549 at s=130GeV) Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  19. 130 AGeV 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 BRAHMS 200 AGeV ? 130AGeV Syst • 200 AGeV • 5100 charged part. observed • Nch  30 pr. part. pair • cf. Nch  20 in p+p at s=200GeV • 50% increase over p+p Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

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

  21. Hadron IdentificationFS (4 deg & 130AGeV)  =3 p-bar C1,H1,T2 m2=p2( t2 / L2 -1) + p p K+ + Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  22. N(pbar)/N(p) @ 130 AGeV 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 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  23. Bjorken limit reached for Au+Au snn= 130GeV? ISR R803 s=63 s=23 BRAHMS PRL sept. 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  24. FS Hadron identificationfor snn = 200 GeV Au+Au TOF and Cherenkov veto in FFS Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  25. K- p- K+ p Particle ratios snn = 200 GeV (y=2) • Y=2 : p-bar/p = 0.48  0.08 -/+= 0.98  0.04 • BRAHMS: Preliminary • Integrated over centrality and pt range Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  26. N(p-bar)/N(p) systematics vs CM energy Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  27. StrangenessK-/K+ vs y @ snn= 130GeV CERN-SPS BRAHMS Preliminary Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  28. How consistent are the models @ snn= 130GeV? Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

  29. RESULTS: 100+100 Nch (0-5%)  5100 dN/d (y=0)  625. FWHM  7.8 N(ch)  30 pr. participant-pair dN/d (y=0)  3.6 pr. part. Pair p-bar/p = 0.48 (y=2) Moderate growth in baryon poor ’plateau’. Total mult. Increases by 25%, Central mult increases by 14% Pbar/p increases by 17% (y=2) Large y and pt coverage to come RESULTS: 65+65 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 snn=130 & 200 GeV Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute

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