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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 Outline 1. Detector setup. 2. General (bulk) characteristics of nucleus-nucleus reactions. 3. Nuclear modification at mid-rapidity 4. Nuclear modification at forward rapidity 5. Elliptic Flow 6. Summary. P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 2 2 Relativistic Heavy Ion Collider PHOBOS BRAHMS PHENIX STAR energies: sNN=200GeV, sNN=62GeV Au+Au P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 Cu+Cu d+Au p+p BRAHMS 3 3 Broad Range Hadron Magnetic Spectrometers Flow Ring 2 Si Ring 1 Tile Ring 1 P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 4 4 Particle production and energy loss Energy density: Bjorken 1983 eBJ = 3/2 (<Et>/ pR2t0) dNch/d assuming formation time t0=1fm/c: yp yp mT dN( B B ) y dy cosh y dy >5.0 GeV/fm3 for AuAu @ 200 GeV Total E=25.72.1TeV >4.4 GeV/fm3 for AuAu @ 130 GeV 72GeV per participant >3.7 GeV/fm3 for AuAu @ 62.4 GeV P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 5 5 Primary versus produced matter BRAHMS NA49 AGS At 200GeV created matter is at picked at y=0 primary matter is concentrated around y3 (y2.2) • longitudinal net-kaon evolution similar as net-proton in |y|< 3 at RHIC (AuAu @ 200 GeV) • strong “association”: net-kaon / net-lambda /net-proton? P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 6 6 High pt suppression 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 into jets of hadrons Schematic view of jet production hadrons leading particle q q 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 leading particle Experimentally depletion of the high pt region in hadron spectra P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 7 7 Charged hadron invariant spectra Nuclear Modification Factor RAA = Yield(AA) NCOLL(AA) Yield(NN) Scaled N+N reference RAA<1 Suppression relative to scaled NN reference SPS: AuAu @200GeV P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 data do not show suppression enhancement (RAA>1) due to initial state multiple scattering (“Cronin Effect”) BRAHMS 8 8 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 P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 9 9 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 P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 10 10 Nuclear modification factors (RCP, RAuAu) for p,K,p at y~3.1 • Suppression for pions and kaons: RAuAu: p < K < p • RAuAu ≠ Rcp (<Ncoll>,<Npart> for 40-60% ~ 70,56) P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 11 11 RAuAu(Y=0) ~ RAuAu(y~3) for central Au+Au at √s = 200 GeV • R AuAu (Y=0) ~ RAuAu(y~3) for pions and protons: accidental? • Rapidity dependent interplay of Medium effect + Hydro + baryon transport P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 12 12 ... 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) Looking for scaling: dN/d ? BE: eBJ = 3/2 (<Et>/ St0) dNch/d S is transwers area of overlaping region <Et> dirived from p 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 P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 13 13 Flowing at forward dN ddptd = dN 1 ddpt 2p (1 + 2v1cos + 2v2(,pt)cos2) 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 P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 14 14 Examine d+Au at all rapidities I. Arsene et al., BRAHMS PRL 93 (2004) 242303. suppression Cronin enhancement P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 15 15 RdAu and RAA for anti-protons and pions @200 BRAHMS PRELIMINARY • suppression for p- but stronger for AuAu • both RdA and RAA show enhancement for p-bar P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 16 16 Summary Strong transverse/elliptic flow in y<3 High energy density >> nuclear density Limiting fragmentation (local) Chemical equilibration Onset of gluon saturation? P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 - y 2 - 25 TeV left for particle production Non-hadronic energy loss through the medium in |y|<3: BRAHMS 17 17 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 P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 18 18 BACKUP SLIDES P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 19 19 Anti-particle to particle ratios Chemical freeze-out BRAHMS PRELIMINARY BRAHMS PRELIMINARY • pbar/p verus K-/K+ : good statistical model •At 200 GeV: p-/p+ = 1.0, K-/K+ = 0.95, pbar/p = 0.75 •At 62 GeV: p-/p+ = 1.0, K-/K+ = 0.84, pbar/p = 0.45, • At |y|<1 matterantimatter P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 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 -/+ It is not true for p+p BRAHMS 20 20 K-/K+ and antihyperon/hyperon K-/K+ = exp((2s - 2u,d)/T) pbar/p = exp(-6u,d/T) s=0 K-/K+ = (pbar/p)1/3 Fit shows that K-/K+ = (pbar/p)1/4 s= ¼ u,d P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 How s= ¼ u,d will work for hyperons? Hbar/H = (pbar/p)3/4 for Lambdas = (pbar/p)1/2 for Xis = (pbar/p)1/4 for Omegas BRAHMS 21 21 RAuAu 200 GeV Cronin enhancement suppression at high pT significant medium effects P. Staszel - Jagiellonian University, Kraków BRAHMS, PRL 91, 072305 (2003) ICHEP, Moscow 2006 BRAHMS 22 22 pbar/p- scaling with Npart sNN=200GeV Strong rapidity dependence pp pp CuCu data consistent with AuAu for the same Npart P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 23 23 K/p ratios at =3.1, Au+Au @200GeV P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 24 24 Strong energy absorption model from a static 2D matter source. (Insprired by A.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 E ~ q.L**2 • q adjusted to give observed RAA at ~1. The change in dN/d will result in slowly rising RAA . The modification of reference pp spectrum causes the RAA to be approximately constant as function of . P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 25 25 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/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 P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 26 26 FS PID using RICH Multiple settings P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 27 27 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 P. Staszel - Jagiellonian University, Kraków quark isospin dominates in pp? ICHEP, Moscow 2006 BRAHMS 28 28 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%) P. Staszel - Jagiellonian University, Kraków ICHEP, Moscow 2006 BRAHMS 29 29