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Phases of matter in the BRAHMS experiment

Phases of matter in the BRAHMS experiment. Paweł Staszel, Marian Smoluchowski Institute of Physics Jagiellonian University for the BRAHMS Collaboration. XXXIII International Conference On High Energy Physics Moscow , 26.07 – 2.08. 200 6. Outline. Detector setup.

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Phases of matter in the BRAHMS experiment

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  1. Phases of matter in the BRAHMS experiment Paweł Staszel, Marian Smoluchowski Institute of Physics Jagiellonian University for the BRAHMS Collaboration XXXIII International Conference On High Energy Physics Moscow, 26.07 – 2.08.2006

  2. Outline Detector setup. General (bulk) characteristics of nucleus-nucleus reactions. Nuclear modification at mid-rapidity Nuclear modification at forward rapidity Elliptic Flow Summary.

  3. BRAHMS Au+Au Cu+Cu d+Au energies: sNN=200GeV, sNN=62GeV p+p Relativistic Heavy Ion Collider PHOBOS PHENIX STAR

  4. Flow Ring 2 Si Ring 1 Tile Ring 1 Broad Range Hadron Magnetic Spectrometers

  5. Total E=25.72.1TeV 72GeV per participant Particle production and energy loss Energy density: Bjorken 1983 eBJ = 3/2 (<Et>/ pR2t0) dNch/d assuming formation time t0=1fm/c: >5.0 GeV/fm3 for AuAu @ 200 GeV >4.4 GeV/fm3 for AuAu @ 130 GeV >3.7 GeV/fm3 for AuAu @ 62.4 GeV

  6. BRAHMS NA49 AGS Primary versus produced matter At 200GeV created matter is at picked at y=0 primary matter is concentrated around y3 (y2.2) • longitudinal net-kaon evolution similar as net-proton • in |y|< 3 at RHIC (AuAu @ 200 GeV) • strong “association”: net-kaon / net-lambda /net-proton?

  7. Schematic view of jet production hadrons leading particle q q leading particle High ptsuppression  jet quenching • Particles with high pt’s (above ~2GeV/c) are primarily produced in hard scattering processes early in the collision • p+p experiments  hard scattered partons fragment intojets of hadrons • In A-A, partons traverse the medium  Probe of the dense and hot stage • If QGP partons will lose a large part of their energy (induced gluon radiation)  suppression of jet production  Jet Quenching Experimentally  depletion of the high pt region in hadron spectra

  8. Nuclear Modification Factor Yield(AA) RAA = NCOLL(AA)  Yield(NN) Scaled N+N reference AuAu @200GeV Charged hadron invariant spectra RAA<1 Suppression relative to scaled NN reference • SPS: data do not show suppression enhancement (RAA>1) due to initial state multiple scattering (“Cronin Effect”)

  9. Energy and System Dependent Nuclear Modification Factors at h~0 and 1 • R AuAu (200 GeV) < RAuAu(63 GeV) < RCuCu(63 GeV) for charged hadrons • p+p at 63 GeV is ISR Data (NPB100), RHIC-Run6 will provide better reference

  10. Control measurement: d+Au @ sNN=200 Suppression in AuAu due to Jet Quenching or due to Initial State Parton Saturation (CGC)? What about d+Au? - Jet Quenching – No - CGC - Yes/No? Excludes alternative interpretation in terms of Initial State Effects  Supports the Jet Quenching for central Au+Au collisions + back-to-back azimuthal correlation by STAR

  11. Nuclear modification factors (RCP, RAuAu) for p,K,p at y~3.1 • Suppression for pions and kaons: RAuAu: <K<p • RAuAu ≠ Rcp (<Ncoll>,<Npart> for 40-60% ~ 70,56)

  12. RAuAu(Y=0) ~ RAuAu(y~3) for central Au+Au at √s = 200GeV • R AuAu (Y=0) ~ RAuAu(y~3) for pions and protons: accidental? • Rapidity dependent interplay of Medium effect + Hydro + baryon transport

  13. Looking for scaling: dN/d ? BE: eBJ = 3/2 (<Et>/ St0) dNch/d Sis transwersarea of overlaping region <Et>dirived from  and K spectra Is the energy density the only parameter that controls RAA? New pp data @62GeV will allow for various comparisions at the same rapidities ... more on RAA rapidity dependence • Similar level of suppresion for central collisions • At forward rapidity RAA shows stronger rise towards peripheral coll. • (surface -> volume emmission)

  14. dN ddptd dN 1 ddpt 2 = (1 + 2v1cos + 2v2(,pt)cos2) Flowing at forward v2 for pion • Understanding missing low-pt fraction is important for integrated v2 from FS • Kaon and proton v2 will come: Statistically Challenging • v2(y~0) ~ v2(y~3) for 0.5<pT<2 GeV/c

  15. suppression Cronin enhancement Examine d+Au at all rapidities I. Arsene et al., BRAHMS PRL 93 (2004) 242303.

  16. RdAu and RAA for anti-protons and pions @200 BRAHMS PRELIMINARY • suppression for - but stronger for AuAu • both RdA and RAA show enhancement for p-bar

  17. Summary Strong transverse/elliptic flow in y<3 High energy density >> nuclear density Limiting fragmentation - y  2 - 25 TeV left for particle production (local) Chemical equilibration Non-hadronic energy loss through the medium in |y|<3: Onset of gluon saturation?

  18. The BRAHMS Collaboration I.Arsene7, I.G. Bearden6, D. Beavis1, S. Bekele6 , C. Besliu9, B. Budick5, H. Bøggild6 , C. Chasman1, C. H. Christensen6, P. Christiansen6, R. Clarke9, R.Debbe1, J. J. Gaardhøje6, K. Hagel7, H. Ito10, A. Jipa9, J. I. Jordre9, F. Jundt2, E.B. Johnson10, C.E.Jørgensen6, R. Karabowicz3, N. Katrynska3, E. J. Kim4, T.M.Larsen11, J. H. Lee1, Y. K. Lee4, S.Lindal11, G. Løvhøjden2, Z. Majka3, M. Murray10, J. Natowitz7, B.S.Nielsen6, D. Ouerdane6, R.Planeta3, F. Rami2, C. Ristea6, O. Ristea9, D. Röhrich8, B. H. Samset11, D. Sandberg6, S. J. Sanders10, R.A.Sheetz1, P. Staszel3, T.S. Tveter11, F.Videbæk1, R. Wada7, H. Yang6, Z. Yin8,and I. S. Zgura9 1Brookhaven National Laboratory, USA, 2IReS and Université Louis Pasteur, Strasbourg, France 3Jagiellonian University, Cracow, Poland, 4Johns Hopkins University, Baltimore, USA, 5New York University, USA 6Niels Bohr Institute, University of Copenhagen, Denmark 7Texas A&M University, College Station. USA, 8University of Bergen, Norway 9University of Bucharest, Romania,10University of Kansas, Lawrence,USA 11 University of Oslo Norway 48 physicists from 11 institutions

  19. BACKUP SLIDES

  20. Chemical freeze-out Anti-particle to particle ratios BRAHMS PRELIMINARY It is not true for p+p BRAHMS PRELIMINARY • pbar/p verus K-/K+ : good statistical model description with B= B(y) with T~170MeV • But this describes also energy depencency at y=0  only B controls the state of matter • STAR and NA47 measures pbar/p versus • -/+ • At 200 GeV: -/+ = 1.0, K-/K+ = 0.95, pbar/p = 0.75 • At 62 GeV: -/+ = 1.0, K-/K+ = 0.84, pbar/p = 0.45, • At |y|<1 matterantimatter

  21. K-/K+ and antihyperon/hyperon How s= ¼ u,d will work for hyperons? Hbar/H = (pbar/p)3/4for Lambdas = (pbar/p)1/2for Xis = (pbar/p)1/4for Omegas K-/K+ = exp((2s - 2u,d)/T) pbar/p = exp(-6u,d/T) s=0  K-/K+ = (pbar/p)1/3 Fit shows that K-/K+ = (pbar/p)1/4  s= ¼ u,d

  22. RAuAu 200 GeV Cronin enhancement suppression at high pT significant medium effects BRAHMS, PRL 91, 072305 (2003)

  23. Strong rapidity dependence CuCu data consistent with AuAu for the same Npart pbar/-scaling with Npart sNN=200GeV pp pp

  24. K/ ratios at =3.1, Au+Au @200GeV

  25. Strong energy absorption model from a static 2D matter source. (Insprired byA.Dainese (Eur.Phys.J C33,495) and A.Dainese , C.Loizides and G.Paic (hep-ph/0406201) ) • Parton spectrum using pp reference spectrum • Parton energy loss DE ~ q.L**2 • q adjusted to give observed RAA at h~1. The change in dN/dh will result in slowly rising RAA . The modification of reference pp spectrum causes the RAA to be approximately constant as function of h .

  26. Summary • Large hadron multiplicities  Almost a factor of 2 higher than at SPS energy( higher )  Much higher than pp scaled results( medium effects) • Identified hadron spectra Good description by statistical model  Large transverse flow consistent with high initial density • v2(pt) is seem to not depend on rapidity • p/ show strong  dependency  for given energy depend only on Npar • High-pT suppression increases with energy for given centrality bin  weak dependency on rapidity of RAA which is consistent with surface jet emission  RCP can hide or enhance nuclear effects  At y=3.2 RAA shows larger suppression than RdA

  27. FS PID using RICH Multiple settings

  28. RdAu Update: Identified Particle RdAu at y~3 + blue - red BRAHMS Preliminary • RdAu of identified particle consistent with published h- results • dAu(p-)/dAu(p+): Valance quark isospin dominates in pp?

  29. Limiting Fragmentation Shift the dNch/d distribution by the beam rapidity, and scale by Npart. Lines up with lower energy  limiting fragmentation Au+Au sNN=200GeV (0-5% and 30-40%) Au+Au sNN=130GeV (0-5%) Pb+Pb sNN=17GeV (9.4%)

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