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Global Observations from PHOBOS

Explore insights from PHOBOS collaboration on high-energy particle collisions, with data analysis and observations on multiplicity, particle spectra, and system convergence. Discover the energy dependence of central dN/dh scale, fragmentation region extent, and empirical scaling rules, shedding light on particle production universality. Unveil the centrality dependence and similarity of AA and e+e- systems at high energy. Dive into PHOBOS data sets covering a broad range of energies and particle behaviors.

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Global Observations from PHOBOS

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  1. Global Observations from PHOBOS Mark D. Baker Brookhaven National Laboratory for the Collaboration Quark Matter 2002 July 18-24, 2002, Nantes Mark D. Baker

  2. Collaboration ARGONNE NATIONAL LABORATORYBirger Back, Alan Wuosmaa BROOKHAVEN NATIONAL LABORATORY Mark Baker, Donald Barton, Alan Carroll, Nigel George, Stephen Gushue, George Heintzelman, Burt Holzman, Robert Pak, Louis Remsberg, Peter Steinberg, Andrei Sukhanov INSTITUTE OF NUCLEAR PHYSICS, KRAKOWAndrzej Budzanowski, Roman Hołyński, Jerzy Michałowski, Andrzej Olszewski, Pawel Sawicki, Marek Stodulski, Adam Trzupek, Barbara Wosiek, Krzysztof Woźniak MASSACHUSETTS INSTITUTE OF TECHNOLOGYMaartin Ballintijn,Wit Busza (Spokesperson), Patrick Decowski, Kristjan Gulbrandsen, Conor Henderson, Jay Kane, Judith Katzy, Piotr Kulinich, Jang Woo Lee, Heinz Pernegger, Corey Reed, Christof Roland, Gunther Roland, Leslie Rosenberg, Pradeep Sarin, Stephen Steadman, George Stephans, Carla Vale, Gerrit van Nieuwenhuizen, Gábor Veres, Robin Verdier, Bernard Wadsworth, Bolek Wysłouch NATIONAL CENTRAL UNIVERSITY, TAIWANChia Ming Kuo, Willis Lin, Jaw-Luen Tang UNIVERSITY OF ILLINOIS AT CHICAGORussell Betts, Edmundo García, Clive Halliwell, David Hofman, Richard Hollis, Aneta Iordanova, Wojtek Kucewicz, Don McLeod, Rachid Nouicer, Michael Reuter, Joe Sagerer UNIVERSITY OF MARYLANDAbigail Bickley, Richard Bindel, Alice Mignerey, Marguerite Belt Tonjes UNIVERSITY OF ROCHESTERJoshua Hamblen, Erik Johnson, Nazim Khan, Steven Manly, Inkyu Park, Wojtek Skulski, Ray Teng, Frank Wolfs Mark D. Baker

  3. The PHOBOS Detector (2001) Spectrometer Vertex 1m Octagon Paddle Trigger Counter Ring Counters Cerenkov Counter 137000 Silicon Pad Channels ZDC ZDC DX magnet DX Magnet 12m Be Beampipe Mark D. Baker

  4. Hits and Tracks in PHOBOS Nearly 4pCoverage Spectrometer p PID f K+ + -5.4 -3 0 +3 +5.4 h Distribution of hits and energy deposition  dN/dh Mark D. Baker

  5. PHOBOS @ QM2002: Physics Topics • Charged Particle Multiplicities • P. SteinbergThursday 18th, 14:30 Session I • Flow and HBT • S. ManlyThursday 18th, 14:30 Session II • Identified Particles • B. WosiekFriday 19th, 14:30 Session I • High pT Hadrons • C. RolandSaturday 20th, 14:30 Session I Mark D. Baker

  6. PHOBOS Data on dN/dh in Au+Auvs Centrality and s 200 GeV 19.6 GeV 130 GeV PHOBOS PHOBOS PHOBOS Preliminary dN/dh Typical systematic band (90%C.L.) h h h Extensive systematic multiplicity data set Mark D. Baker

  7. v2 vs h and s Preliminaryv2200 Final v2130 Averaged over Centrality PHOBOS Au+Au nucl-ex/0205021 200 GeV 130 GeV From talk by S. Manly Mark D. Baker

  8. Charged Hadron Spectra out to High pT Mark D. Baker See talk by Christof Roland

  9. v2 vs pT (200 GeV) 0 < h < 1.5 200 GeV Au+Au v2 Averaged over centrality PHOBOS preliminary pT (GeV/c) Mark D. Baker

  10. Yields at Low pT (Au+Au @ 200 GeV) 15% central -0.1< y <0.4 p++ p- K+ + K- 1/(2pT)d2N/dydpT p + p PHOBOS preliminary See talk by Barbara Wosiek pT (GeV/c) Mark D. Baker

  11. Broad range systematic dataset • Au+Au at s=19.6, (56), 130, & 200 GeV • d2N/dhdf over 11 units of h, 2p in f • d2N/dpTdyup to a pT of 5 GeV/c • Global Observations • Empirical Scaling Rules Mark D. Baker

  12. Energy Dependence of Central dN/dh Scale by Npart/2 & shift to h¢=h- ybeam PHOBOS Au+Au dNch/dh dNch/dh ¢/<Npart> 6% central PHOBOS Au+Au 19.6 GeV is preliminary 19.6 GeV is preliminary Systematic errors not shown The “fragmentation region” extent grows with sNN Mark D. Baker

  13. Rule 1: Universal Limiting Curve for Particle Production UA5, Z.Phys.C33, 1 (1986) p + p inel. dNch/dh ¢/<Npart> 6% central dN/dh¢ PHOBOS Au+Au 19.6 GeV is preliminary Systematic errors not shown Mark D. Baker

  14. Total Multiplicity for AA and pp (pp) AA data is central 19.6 GeV is preliminary Mark D. Baker

  15. Remove the “Leading Proton” Effect seff s Basile et al (1980-1984) pQCD e+e- Calculation (A. Mueller, 1983) Mark D. Baker

  16. Comparison of áNchñ vs. Energy pQCD e+e- Calculation Mark D. Baker

  17. Different systems converge at high energy. Universality of Nch? Comparison of áNchñ vs. Energy e+e- PHOBOS Preliminary Central Au+Au pp (pp) data @ seff Central AA 1 10 102 103 s (GeV) From talk by P. Steinberg Mark D. Baker

  18. Rule 2: Similarity of AA and e+e-at High Energy 200 GeV e+e- measures dN/dyT(rapidity relative to“thrust” axis) Mark D. Baker

  19. _ pp Centrality Dependence at Mid-rapidity PHOBOS Au+Au 200 GeV PRC 65 (2002) 061901R 130 GeV 19.6 GeV preliminary See Aneta Iordanova’s Poster Mark D. Baker

  20. Nch scales with Npart Error bands due to high-h extrapolation Au+Au (preliminary) Total charged particle production ~ Npart Mark D. Baker

  21. Centrality dependence dNch/dh¢ Results : Limiting Fragmentation vs Centrality • Shape changes with centrality • Full integral changes very little with centrality PHOBOS Au+Au 0-3% central 35-40% central 200 GeV 19.6 GeV preliminary Systematic errors not shown Mark D. Baker

  22. Charged Hadron Spectra • Normalize by <Npart>/2 • Divide by the value at Npart=65 Mark D. Baker

  23. Normalize by Npart/2. Divide by the value at Npart=65 Collision scaling would imply: PHOBOS Preliminary: Au+Au 200 GeV UA1 pp (200 GeV) Rule 3: Particle Production Scales with Npart Mark D. Baker See Christof Roland’s talk

  24. Global Observations for AA Particle Production • Broad, systematic dataset • Empirical Scaling Rules • Universal Limiting Curve for Particle Production • No broad boost-invariant region • Similarity of AA and e+e- at High Energy • Particle production scales with Npart • Even at pT of 4-5 GeV/c! Mark D. Baker

  25. Backup slides Mark D. Baker

  26. Many ways to slice pz Rapidity: Generalized velocity Feynman x: scaled pz Pseudorapidity: ~y: easier to measure Away from mid-rapidity: Mark D. Baker

  27. Universal Behaviorof Charged Particle Multiplicitiesin Heavy-Ion Collisions Peter Steinberg Brookhaven National Laboratory for the PHOBOS Collaboration Quark Matter 2002 July 18-24, 2002, Nantes

  28. Rapidity Distributions at 200 GeV q q 200 GeV Central Au+Au e+e- measures dN/dyT(rapidity relative to“thrust” axis) h yT AA/pp ~ 1.4-1.5 Surprising agreement in shape between AA/e+e- /pp Correspondence between perturbative and non-perturbative approaches? Mark D. Baker

  29. (dN/dyT ) e+e- scales likeAA near midrapidity Particle density near midrapidity Mark D. Baker

  30. A+A e+e- pp/pp (Mueller 1983) Total Multiplicity vs. Beam Energy Central A+A Mark D. Baker

  31. Above n~3, pion yields constant Central AA has n~5-6 per participant Scaling with Npart Reduces leading particle effect Scaling with s NA49 SPS Relative yield of p in pA/pp for y>0 NA49 (unpublished) CERN-SPSLC-P-264-ADD-5 How can AA scale like e+e-? E910 pA collisions NA49 n counts # collisions Npart=n+1 • With increasing n • Proton “stops” (i.e. deposits energy) • Pion yield saturates Mark D. Baker

  32. Centrality Dependence of Nch Error band due to high-h extrapolation sinel=42 mb (RHIC) Au+Au sinel=33 mb (SPS) sinel=21 mb (AGS) Glauber Monte Carlo 19.6 GeV Preliminary The Return of the Wounded Nucleon Model… Bialas & Czyz 1976, Elias et al 1978 Mark D. Baker

  33. Scaling of Charged Hadron pT distributions in Au+Au collisions at 200 GeV Christof Roland MIT for the PHOBOS Collaboration Quark Matter 2002 July 18-24, 2002, Nantes

  34. Spectrometer Performance Acceptance Momentum Resolution • Data Sample Production Run 2001(200 GeV) • 7.8 M Au+Au Events, Min. Bias Trigger • 32 M reconstructed particles Mark D. Baker

  35. PHOBOS-Spectra @ 200GeV • Spectra corrected for • Acceptance/Efficiency • Ghost Tracks • Momentum resolution • Variable bin width • Secondaries • At 200GeV min. bias. pp reference data exists _ 0.2<yp<1.4 Mark D. Baker

  36. _ Centrality Npart 45-50% 65 ± 4 35-45% 93 ± 5 25-35% 138 ± 6 15-25% 200 ± 8 6-15% 276 ± 9 0-6% 344 ± 12 Scaled Spectra / pp-Fit PHOBOS Preliminary • Centrality range: • <b> from 10 to 3 fm • <n> from 3 to 6 Mark D. Baker

  37. UA1 200 GeV Centrality scaling in pT bins Relative Yield Npart Spectra normalized to yield at Npart = 65 Mark D. Baker

  38. Comparison to Lower Energies • Data taken at 130GeV shows similar trends • Shape is consistent with measurements by STAR Relative Yield Mark D. Baker

  39. sinel=42 mb (RHIC) sinel=33 mb (SPS) sinel=21 mb (AGS) Glauber Monte Carlo Number of collisions at different Energies Mark D. Baker

  40. Integrated Yields vs Centrality dN/dy – Spectra Integral dN/dh - Multiplicity data Mark D. Baker

  41. Mean pT vs centrality Mark D. Baker

  42. UA1 200 GeV Centrality scaling in pT bins Relative Yield Npart Spectra normalized to FIT to yield at Npart = 65 Mark D. Baker

  43. Evolution with Centrality PHOBOS • Follow change of shape vs most peripheral bin. Mark D. Baker

  44. x z Events Dt (ns) Triggering on Interactions Positive Paddles Negative Paddles ZDC N ZDC P Au Au PN PP • Coincidence between • Paddle counters • Paddle + ZDC timing reject background Valid Collision Mark D. Baker

  45. b b Peripheral Central x 2 6 4 2 Centrality Determination Data • HIJING +GEANT • Glauber calculation • Model of paddle trigger Paddle signal Data+MC Nparticipants Mark D. Baker

  46. Flow and Bose-Einstein Correlations in Au-Au Collisions at RHIC Steven Manly (Univ. of Rochester) For the PHOBOS Collaboration Flow constitutes the bulk of this talk Probe the source dynamics through correlations Mark D. Baker

  47. Select vertices offset in z, symmetric coverage in ,  RingsN Octagon RingsP f h Flow: Hit-based method nucl-ex/0205021 submitted to PRL Mark D. Baker

  48. Reaction plane determined by subevents in -2<<2 RingsN Octagon RingsP f h Flow: Hit-based method nucl-ex/0205021 submitted to PRL Select vertices offset in Z, symmetric coverage in ,  Mark D. Baker

  49. Elliptic flow (v2) determined for ||<5.3 RingsN Octagon RingsP f h Flow: Hit-based method nucl-ex/0205021 submitted to PRL Select vertices offset in Z, symmetric coverage in ,  Reaction plane determined by subevents in -2<<2 Mark D. Baker

  50. Reaction plane determined by hits in widely separated subevent regions, symmetric in ,  Vertex measurement Flow: Track-based New for QM2002! Mark D. Baker

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