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Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute1 nReaction features in 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au-AU collisions nEM dissociation.

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Presentation on theme: "Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute1 nReaction features in 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au-AU collisions nEM dissociation."— Presentation transcript:

1 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute1 nReaction features in 65 AGeV + 65 AGeV and 100 AGeV AGeV Au-AU collisions nEM dissociation ndN(ch)/d  distribution -4<  <4 vs. Collision Centrality nProduction of charged particles, N(ch)/pr.participant nBjorken limit attained ? Transparency or Stopping np-bar/p vs y, b, p t nStrangeness vs y nFuture BRAHMS Y RHIC:  s nn =130 GeV, and  s nn =200 GeV

2 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute2 I.G. Bearden 7, D. Beavis 1, C. Besliu 10, Y. Blyakhman 6, J. Bondorf 7, J.Brzychczyk 4, B. Budick 6, H. Bøggild 7, C. Chasman 1, C. H. Christensen 7, P. Christiansen 7, J.Cibor 4, R.Debbe 1, J. J. Gaardhøje 7, K. Grotowski 4, K. Hagel 8, O. Hansen 7, H. Heiselberg 7, A. Holm 7, A.K. Holme 12, H. Ito 11, E. Jacobsen 7, A. Jipa 10, J. I. Jordre 10, F. Jundt 2, C. E. Jørgensen 7, T. Keutgen 9, E. J. Kim 5, T. Kozik 3, T.M.Larsen 12, J. H. Lee 1, Y. K.Lee 5, G. Løvhøjden 2, Z. Majka 3, A. Makeev 8, B. McBreen 1, M. Murray 8, J. Natowitz 8, B.S.Nielsen 7, K. Olchanski 1, D. Ouerdane 7, R.Planeta 4, F. Rami 2, D. Roehrich 9, B. H. Samset 12, S. J. Sanders 11, I. S. Sgura 10, R.A.Sheetz 1, Z.Sosin 3, P. Staszel 7, T.S. Tveter 12, F.Videbæk 1, R. Wada 8 and A.Wieloch 3. 1 Brookhaven National Laboratory, USA 2 IReS and Université Louis Pasteur, Strasbourg, France 3 Jagiellonian University, Cracow, Poland 4 Institute of Nuclear Physics, Cracow, Poland 5 Johns Hopkins University, Baltimore, USA 6 New York University, USA 7 Niels Bohr Institute, Blegdamsvej 17, University of Copenhagen, Denmark 8 Texas A&M University, College Station. USA 9 University of Bergen, Norway 10 University of Bucharest, Romania 11 University of Kansas, Lawrence,USA 12 University of Oslo Norway BRAHMS Intl. collaboration

3 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute3 RHIC physics August 2000 & August :00 o’clock 4:00 o’clock 6:00 o’clock 8:00 o’clock 10:00 o’clock STAR PHENIX RHIC AGS LINAC BOOSTER TANDEMS 9 GeV/u Q = MeV/u Q = +32 HEP/NP  g-2 U-line BAF (NASA) BRAHMS: L peak = 3.3  cm -2 s -1 L ave = 1.7  cm -2 s -1 Rcoll= 350 Hz PHOBOS 6  b -1 2 wks August 2000 and 2001

4 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute4 BRAHMS in the 2’ hall … in 1998

5 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute5 Forward & Midrapidity spectrometers FS: 2 TPC, 2 TOF, C1-threshold, 3 Drift Ch. Mod., RICH, 4 Dipoles deg.  = MRS: 2 TPC, 1 Dipole, 1TOF deg.  =

6 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute6 First BRAHMS collision at 100 AGeV+100AGeV T1 MTPC1 T2 MTPC2 MRS: 90 deg 6.5 msr FS: 6 deg 0.8 msr

7 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute7 BRAHMS acceptance August 2000 & 2001

8 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute8 Global detectors SiMA, TMA, BB  SiMA (-2.0<  <2.0)  PTMA (-2.2<  <2.2)  Beam-Beam (3 < |  | < 4) 97%  (geom)

9 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute9 Centrality determination Vertex distribution 1m

10 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute10 Electromagnetic nuclear dissociation LO+NLO Mutual EM 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. EM dissociation selected by ZDC coincidences and TMA Veto in BRAHMS n n n 2n 1n LO NLO

11 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute11 Neutral Energy correlations (ZDC) C2(E L,E R )=P(E L,E R )/(P(E L )*P(E R ))

12 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute12 dN ch /d  s nn = 130 GeV SiMA, TMA, BB, TPC nN=  dE / nP(0)/P(n  1) nBackground corr.due to secondaries (37-50%) nConsistency between 4 independent detector systems n65 AGeV+ 65 AGeV: n  N(ch)d  = 4050±300 nCentral 0-5% dN(ch)/d  (  =0) =550 nFWHM of distribution  = 7.6  % 10-20% 20-30% 30-40% 40-50% 5-10% 600 BRAHMS Subm. Phys. Lett. B 7/2001.

13 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute13 TPC tracks, Vertex reconstruction, Charged particle track density MTPC1 z y

14 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute14 Charged Particle Mult.  s nn =130 GeV BRAHMS. Subm. to Phys Lett. B SPS

15 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute15 N Charged vs. number of participant nucleon pairs.  s nn =130AGeV ndN/d   3 (  =0) pr.part pair. nCf. HIJING, FRITIOF nNo saturation effects observed Claus Ekman Jørgensen. Thesis NBI 2001 FRITIOF HIJING MTPC1 CEJ EKRT

16 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute16 RHIC: 200 AGeV Will this happen?

17 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute17 dN ch /d  for 100 AGeV AGeV n100 AGeV AGeV Au+Au n  N(ch)d  = 5100±300 nCentral 0-6% dN(ch)/d  (  =0) =610  50 nFWHM of distribution  = 7.9  1.0 BRAHMS 200AGEV

18 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute18 Hard and Soft vs. High Density 200 AGeV nKharzeev and Levin (nucl-th/ ) nSoft-Hard: dN/d  =(1-X) n pp /2 + X n pp =1049, =339, npp=2.43 =>dN/d  =668 (with X=0.9) nHigh Density QCD-saturation: dN/dy = f( Npart, Q s 2,,  QCD,  s,y) with =0.3 from HERA data => dN/d  =620 (using dN/d  =549 at  s=130GeV)

19 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute19 Total production of Charged particles n130 AGeV n4000 charged part. observed nNch  23.5 pr. part. pair ncf. Nch  17 in p+p at  s=130GeV n35-40% increase over p+p Syst ? BRAHMS 200 AGeV 130AGeV n200 AGeV n5100 charged part. observed nNch  30 pr. part. pair ncf. Nch  20 in p+p at  s=200GeV n50% increase over p+p

20 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute20 Hadron identification MRS (90, 40 deg) m 2 =p 2 ( t 2 / L 2 -1) p-bar  KK p  =0  =3 p K  0 p, pbar K±  

21 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute21 Hadron Identification FS (4 deg & 130AGeV)  p-bar  =3 C1,H1,T2 ++ p m 2 =p 2 ( t 2 / L 2 -1) ++ p K+

22 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute AGeV Centrality and P t dependence nAntiproton absorbtion correction to pbar/p ratio: 5 % for FS at 4 deg 2 % for MRS at 90, 40 deg n10% corr. (low pt) p from Be-tube nApplied to data nMost pbar and p from Hyperon decays fall into spectrometer acceptance. nCorrection factor depends on H/B, H-bar/B-bar and T B /T H For H/B < 0.5 systematic correction is <  5% on ratio nModel dependent  not applied to data

23 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute23 Bjorken limit reached for Au+Au  s nn = 130GeV? ISR R803  s=23  s=63 BRAHMS PRL sept. 2001

24 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute24 FS Hadron identification for  s nn = 200 GeV Au+Au TOF and Cherenkov veto in FFS

25 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute25 Particle ratios  s nn = 200 GeV (y=2) nY=2 : p-bar/p = 0.48  0.08  -/  += 0.98  0.04 nBRAHMS: Preliminary nIntegrated over centrality and pt range K-K- p-p- K+K+ p

26 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute26 N(p-bar)/N(p) systematics vs CM energy

27 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute27 Strangeness K-/K+ vs  s nn = 130GeV BRAHMS Preliminary CERN-SPS

28 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute28 How consistent are the  s nn = 130GeV?

29 Sept 4, 2001Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute29 Summary: First Au+Au  s nn =130 & 200 GeV RESULTS: nNch (0-5%)  5100 ndN/d  (y=0)  625.  FWHM  7.8 nN(ch)  30 pr. participant-pair ndN/d  (y=0)  3.6 pr. part. Pair np-bar/p = 0.48 (y=2) nModerate growth in baryon poor ’plateau’. nTotal mult. Increases by 25%, nCentral mult increases by 14% nPbar/p increases by 17% (y=2) nLarge y and pt coverage to come RESULTS: nNch (0-5%)  4000 ndN/d  (y=0)  550.  FWHM  7.6 nN(ch)  23 pr. participant-pair ndN/d  (y=0)  3 pr. part. Pair nAntiMeson/Meson close to unity np-bar/ p vs y shows increased but still incomplete transparency nMidrapidity Plateau? ny =0,0.7,2 : pbar/p  0.64, 0.66, 0.41 (±0.05 ± 0.06) nWeak pt and centrality dependence nBjorken limit not reached nModels inconsistent with data


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