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Scaling Properties in Heavy Ion Collisions

Scaling Properties in Heavy Ion Collisions. Nigel George – BNL For the Collaboration. AGS/RHIC Users Meeting September 20-21, 2002, BNL. Collaboration. ARGONNE NATIONAL LABORATORY Birger Back, Alan Wuosmaa

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Scaling Properties in Heavy Ion Collisions

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  1. Scaling Properties in Heavy Ion Collisions Nigel George – BNL For the Collaboration AGS/RHIC Users Meeting September 20-21, 2002, BNL

  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

  3. The PHOBOS Detector (2001) f -5.4 -3 0 +3 +5.4 h 137000 Silicon Pad Channels Spectrometer 1m Ring Counters Octagon Nearly 4pCoverage

  4. QGP Signatures and Scaling with System Size and Energy • QGP signatures/diagnostics • Strangeness enhancement • Entropy production • J/psi suppression • Jet quenching • Scaling violations relative to • Reference (e.g. p+p, p+A) • Scaling assumption (Npart, Ncoll) • Study scaling properties for • ‘Bulk’ particle production • High pT hadrons

  5. Systematic level arm sinel=42 mb (RHIC @ 200) 6 21 sinel=33 mb (SPS) 3 sinel=21 mb (AGS) 7 Glauber Monte Carlo 2x increase in Ncoll/(Npart/2) Over centrality range Over energy range 65 20 200 GeV 355

  6. PHOBOS Data on dN/dh in Au+Au vs Centrality and s 200 GeV 19.6 GeV 130 GeV PHOBOS PHOBOS PHOBOS dN/dh Typical systematic band (90%C.L.) h Extensive systematic multiplicity data set “Fragmentation region” dN/dh @ h= 0 Integral : <NCh> h = 0 h = ybeam

  7. Scale by Npart/2 & shift to h¢=h- ybeam dNch/dh ¢/<Npart> 6% central PHOBOS Au+Au Systematic errors not shown ybeam ybeam The “fragmentation region” extent grows with sNN No broad boost-invariant region Energy dependence of dN/dh shape PHOBOS Au+Au dNch/dh

  8. UA5, Z.Phys.C33, 1 (1986) p + p inel. dN/dh¢ dNch/dh ¢/<Npart> 6% central PHOBOS Au+Au Systematic errors not shown Universal Limiting Curve in AA “fragmentation region” 19.6 data allows extrapolation to extract Nch Significant particle production in AA “fragmentation region”

  9. Total Charged Multiplicity Systematic errors not shown

  10. Physical relevance of the slope? Systematic errors not shown Why is the Slope( ) closer to e+e- than pp? Systematic errors not shown

  11. Need to consider “leading particle effect in pp” Measured by Basile et al (1980-1984) seff s pQCD e+e- Calculation (A. Mueller, 1983)

  12. Comparison <NCh> vs. Energy

  13. Comparison <NCh> vs. Energy e+e- PHOBOS Central Au+Au e+e- pp (pp) data @ seff Central AA Different systems converge at high energy. Universality of Nch? 1 10 102 103 s (GeV)

  14. AA and e+e- @ 200GeV similar in shape 200 GeV e+e- measures dN/dyT(rapidity relative to“thrust” axis)

  15. (dN/dyT ) e+e- scales like AA near midrapidity Particle density near midrapidity

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

  17. Mid-rapidity multiplicity dependence on Npart Preliminary Systematic errors not shown dN/dh varies from Npart scaling

  18. PT distribution of charged particles Phobos Preliminary “Soft” part of spectrum Systematic Errors not shown What about high pt? “Hard” part of spectrum Different regime from measurements ..

  19. Does Npart scaling work at high pt? Pt dependence of yields at midrapidity (y~0.8)

  20. Centrality dependence in the low pT regime Charged particle mid-rapidity density Phobos Preliminary Phobos Preliminary Centrality dependence of spectra consistent with charged particle dependence

  21. Npart scaling in the high pt regime Phobos Preliminary Phobos Preliminary

  22. Npart Scaling at high pT PHOBOS Preliminary Ncoll-scaling Normalized to yield at Npart = 65 • Npart scaling describes data at pT ~ 4.25 GeV/c

  23. Summary • Universal limiting curve for particle production - No broad boost-invariant region • Total particle production scales with Npart • - High pt production also scales with Npart • Universality of energy dependence of <NCh> in e+e-,pp,AA collisions • - Similarity of dN/dh in AA and e+e- at high energies

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