1 / 35

Results from the BRAHMS experiment at RHIC

Results from the BRAHMS experiment at RHIC. Dieter Röhrich Fysisk institutt, Universitetet i Bergen for the BRAHMS collaboration Experimental setup Stopping Particle production Charged particle pseudo-rapidity distribution Rapidity dependence of ratios of identified particles.

chione
Download Presentation

Results from the BRAHMS experiment at RHIC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Results from the BRAHMS experiment at RHIC Dieter Röhrich Fysisk institutt, Universitetet i Bergen for the BRAHMS collaboration • Experimental setup • Stopping • Particle production • Charged particle pseudo-rapidity distribution • Rapidity dependence of ratios of identified particles

  2. BRAHMS 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. Wada8and A.Wieloch3. 1Brookhaven National Laboratory, USA2IReS 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, University of Copenhagen, Denmark 8Texas A&M University, College Station, USA 9University of Bergen, Norway 10University of Bucharest, Romania 11University of Kansas, Lawrence,USA 12University of Oslo, Norway

  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

  4. Centrality detectors Tiles Silicon strips Beam-Beam counters Zero-degree calorimeters Twomovable spectrometers Midrapidity spectrometer Forward Spectrometer BRAHMS detector • Broad RAnge Hadron Magnetic Spectrometer

  5. Global detectors: SiMA, TMA, BB, ZDC 97% (geom) • SiMA (-2.0< <2.0) • TMA (-2.2<  <2.2) • Beam-Beam (3 < | | < 4)

  6. Multiplicity measurement Si strips + tiles Corrected for vertex position dependence Centrality determination 1m

  7. 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

  8. First BRAHMS collision at 100 AGeV+100AGeV T2 FS: 6 deg 0.8 msr T1 Dipole Magnets MRS: 90 deg 6.5 msr MTPC1 MTPC2

  9. Spectrometer acceptanceAugust 2000 & 2001 BFS FFS

  10. TPC tracking and vertex reconstruction y z MTPC1

  11. Hadron identification MRS (90, 40 deg)  K p 0  K± p-bar =3 p, pbar =0 p K  m2=p2( t2 / L2 -1)

  12. Hadron identificationFS (4 deg & 200AGeV) (1) TOF (H1) and Cherenkov (C1) veto in FFS C1,H1,T2

  13. K- p- K+ p Hadron identificationFS (4 deg & 200AGeV) (2) • C1 Cerenkov pion threshold ~2.7GeV/c • C1 segmented in 32 6.35cm x 6.35 cm pixels. • Mean # of tracks/event ~1.4 • TOF resolution roughly 25% better than in 2000 • TOF K/p in FFS upto 5GeV/c • TOF pi/K in FFS to 3GeV/c

  14. Hadron identificationFS (200AGeV) (3) • Full PID in FS • Ring Imaging Cerenkov Detector (RICH) • Secondary ToF counter (H2) • PID up to 25 GeV/c

  15. Proton rapidity distribution • AGS energies • Central collisions • Energy dependence B. Back et al., E917 Collaboration, Phys. Rev. Lett. 86 (2001) 1970

  16. Stopping F. Videbæk, nucl-ex/0106017 • Rapidity loss • energy dependence

  17. SPS central (6%) Pb+Pb, 158 GeV/nucl. NA49 RHIC central (6%) Au+Au, sNN= 130 GeV BRAHMS, STAR Net proton rapidity distribution G.Cooper et al. (NA49 Collaboration), Nucl. Phys.A661 (1999) 362c-365c C. Adler et al. (STAR), subm. Phys. Rev. Lett.; F. Videbæk (BRAHMS), QM01

  18. FRITIOF 7.02 HIJING Net proton rapidity distribution – model predictions • BRAHMS (central) preliminary

  19. SPS central (14%) Pb+Pb, 158 GeV/nucl. NA49 RHIC central (40%) Au+Au, sNN= 130 GeV BRAHMS Antiproton/proton ratio – rapidity dependence I.G. Bearden et al., (BRAHMS), Phys. Rev. Lett. 87 (2001) G.Cooper et al. (NA49),Nucl. Phys.A661 (1999) 362c; G. Veres et al. (NA49),Nucl. Phys.A661 (1999) 383c

  20. SPS Pb+Pb, 158 GeV/nucl. NA49 RHIC Au+Au, sNN= 130 GeV BRAHMS Antiproton/proton ratio – centrality dependence G.Cooper et al. (NA49),Nucl. Phys.A661 (1999) 362c; G. Veres et al. (NA49),Nucl. Phys.A661 (1999) 383c I.G. Bearden et al., (BRAHMS), Phys. Rev. Lett. 87 (2001)

  21. Energy systematics RHIC, Au+Au sNN= 130 GeV sNN= 200 GeV Antiproton/proton ratio – energy dependence RHIC, central Au+Au, BRAHMS J.J. Gaardhøje, (BRAHMS), CIPPQG (2001)

  22. Particle production dNch/d @ snn= 130 GeV 65 AGeV+ 65 AGeV • Charged particle pseudorapidity distribution • SiMA, TMA, BB, TPC • Consistency between 4 independent detector systems • Central 0-5% •  N(ch)d= 4050±300 • dN(ch)/d (=0) = 553  1  36 • FWHM of distribution = 7.6 0.7 600 0-5% 5-10% 10-20% 20-30% 30-40% 40-50% BRAHMS subm. Phys. Lett. B (2001)

  23. Number of Participants From HIJING • dN/dh ~ 3.2 per participant nucl. pair at h=0 for central (0-5%); <Npart>=346 • Enhancement of particle production for central collisions at mid-rapidity • At high rapidities (h >3) particle production scales with Npart

  24. SPS dNch/dh vs. participant nucleon pairs@ snn=130 GeV

  25. dNch/dh and model predictions • snn=130 GeV FRITIOF HIJING C. E. Jørgensen, Thesis NBI 2001

  26. Particle production dNch/d @ snn= 200 GeV 100 AGeV+ 100 AGeV • Charged particle pseudorapidity distribution • SiMA, BB • Central 0-6% •  N(ch)d= 5100 ±300 • dN(ch)/d (=0) = 610  50 • FWHM of distribution = 7.9 1.0

  27. dNch/dh vs. participant nucleon pairs @ snn=200 GeV • Soft-Hard: • dN/d=(1-X) npp <Npart>/2 • + X npp <Ncoll> • with <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=130 GeV) Kharzeev and Levin (nucl-th/0108006)

  28. dNch/dh vs. participant nucleon pairs - energy dependence • 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 BRAHMS 200 AGeV ? 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

  29. Rapidity dependence of ratios of identified particles - how consistent are the models @ snn= 130GeV?

  30. Rapidity dependence of K-/K+ratio @ snn= 130GeV BRAHMS preliminary BRAHMS preliminary

  31. Transverse momentum dependence of ratios of identified particles (1) • snn= 130GeV • Ratios at y  0 • 0-40% central • No observed dependence on centrality • No strong pt-dependence • N(-)/N(+) = 0.990.02 • N(K-)/N(K+) = 0.900.06

  32. Transverse momentum dependence of ratios of identified particles (2) • snn= 130GeV • Ratios at y  0 • 0-40% central • N(K)/N(p) increases with pt (0.16 – 0.6) • N(p)/N(p) increases with pt ; pbar(p) > p-(p+) for pt > 2 GeV/c

  33. Ratios of identified particles and jet quenching • Anomalous antiproton to negative pion ratio as revealed by jet quenching I. Vitev, M. Gyulassy, hep-ph/0108045 • Kaon/pion ratio as probes of jet quenching and initial density in AA collisions P. Levai, SQM2001

  34. Thermal models at RHIC BRAHMS Preliminary y2 y0 F. Becattini, J. Cleymans, A. Keranen, E. Suhonen, K. Redlich, Phys.Rev. C64 (2001) 024901

  35. Summary: Au+Au snn=130 & 200 GeV • RESULTS: 100 + 100 • Nch (0-5%)  5100 • dN/d (y=0)  610. FWHM  7.9 • dN/d (y=0)  3.6 pr. part. pair • Central mult increases by 14% • Pbar/p  0.48 ± 0.08 (y  2) • -/+= 0.990.01 (y  3) • Large y and pt coverage to come • RESULTS: 65 + 65 • Nch (0-5%)  4050 • dN/d (y=0)  553; FWHM  7.6 • dN/d (y=0)  3.14 pr. part. pair • Pbar/p = 0.64 ± 0.05 ± 0.06 (y  0) • = 0.66 ± 0.05 ± 0.06 (y  0.7) • = 0.41 ± 0.05 ± 0.06 (y  2) • -/+= 0.990.02 (y  0) • K-/K+ = 0.900.06 (y  0) • = 0.830.1 (y  2.5) • No (weak) pt and centrality dependence

More Related