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 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
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 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
RHIC physics August 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 STAR 4:00 o’clock 6:00 o’clock 6 b-1 U-line 9 GeV/u Q = +79 BAF (NASA) m g-2 LINAC BOOSTER 2 wks AGS HEP/NP 1 MeV/u Q = +32 TANDEMS August 2000 and 2001 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute BRAHMS in the 2’ hall … in 1998 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
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 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
First BRAHMS collision at 100 AGeV+100AGeV FS: 6 deg 0.8 msr T1 MRS: 90 deg 6.5 msr MTPC1 MTPC2 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
BRAHMS acceptance August 2000 & 2001 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Global detectors SiMA, TMA, BB 97% (geom) SiMA (-2.0< <2.0) PTMA (-2.2< <2.2) Beam-Beam (3 < | | < 4) Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Centrality determination Vertex distribution Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Electromagnetic nuclear dissociation 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 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Neutral Energy correlations (ZDC) C2(EL,ER)=P(EL,ER)/(P(EL)*P(ER)) Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
dNch/d @ snn= 130 GeV SiMA, TMA, BB, TPC BRAHMS Subm. Phys. Lett. B 7/2001. N=dE /<dE> P(0)/P(n1) 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% Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
TPC tracks, Vertex reconstruction, Charged particle track density z MTPC1 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Charged Particle Mult. snn=130 GeV SPS BRAHMS. Subm. to Phys Lett. B. 2001 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
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 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
RHIC: 200 AGeV Will this happen? Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute dNch/d for 100 AGeV + 100 AGeV BRAHMS 200AGEV 100 AGeV + 100 AGeV Au+Au N(ch)d= 5100±300 Central 0-6% dN(ch)/d (=0) =61050 FWHM of distribution = 7.9 1.0 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
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) Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Total production of Charged particles BRAHMS 200 AGeV ? 130AGeV Syst 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 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 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Hadron identification MRS (90, 40 deg) K p 0 K± p-bar =3 p, pbar =0 p K m2=p2( t2 / L2 -1) Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Hadron Identification FS (4 deg & 130AGeV) =3 p-bar C1,H1,T2 m2=p2( t2 / L2 -1) + p p K+ + Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
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 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Bjorken limit reached for Au+Au snn= 130GeV? ISR R803 s=63 s=23 BRAHMS PRL sept. 2001 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
FS Hadron identification for snn = 200 GeV Au+Au TOF and Cherenkov veto in FFS Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Particle ratios snn = 200 GeV (y=2) K- p- Y=2 : p-bar/p = 0.48 0.08 -/+= 0.98 0.04 BRAHMS: Preliminary Integrated over centrality and pt range K+ p Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute N(p-bar)/N(p) systematics vs CM energy Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Strangeness K-/K+ vs y @ snn= 130GeV CERN-SPS BRAHMS Preliminary Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
How consistent are the models @ snn= 130GeV? Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute
Summary: First Au+Au snn=130 & 200 GeV 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 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 Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute