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Russell Betts (UIC) for the PHOBOS Collaboration

The Growth of the Fragmentation Region in Ultra-Relativistic Heavy Ion Collisions. Russell Betts (UIC) for the PHOBOS Collaboration. Universal Behavior of Charged Particle Multiplicity dN/d  and N Total as a function of s NN Talks by RB, Aneta Iordanova and David Hofman.

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Russell Betts (UIC) for the PHOBOS Collaboration

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  1. The Growth of the Fragmentation Region in Ultra-Relativistic Heavy Ion Collisions Russell Betts (UIC) for the PHOBOS Collaboration Universal Behavior of Charged Particle Multiplicity dN/d and NTotal as a function of sNN Talks by RB, Aneta Iordanova and David Hofman Russell Betts DNP Meeting MSU Oct 2002

  2. The PHOBOS 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 Russell Betts DNP Meeting MSU Oct 2002

  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 Russell Betts DNP Meeting MSU Oct 2002

  4. Centrality Determination Summed Signals in Paddle Counters (200 and 130 GeV) Total Energy Deposited in Octagon (19.6 GeV) Counts Summed Paddle Signal Percentage of Cross Section + Glauber Model  NParticipants Russell Betts DNP Meeting MSU Oct 2002

  5. -5.4 -3 0 +3 +5.4 h Multiplicity Measurement Octagon Rings • Hit Counting in Octagon and Rings plus Poisson Statistics. • Energy Deposition to count MIPs. • (Tracklets in Vertex and Spectrometer – See A.I. Talk) Russell Betts DNP Meeting MSU Oct 2002

  6. PHOBOS Data on dN/dh 200 GeV 19.6 GeV 130 GeV PHOBOS PHOBOS PHOBOS nucl-ex/0210015 Typical systematic error band (90%C.L.) dN/dh h h h Extensive and Systematic Data Set Russell Betts DNP Meeting MSU Oct 2002

  7. Energy Dependence of Central dN/dh Scale by Npart/2 & Shift to h¢ = h - ybeam PHOBOS Au+Au dNch/dh 6% central dNch/dh ¢/<Npart/2> PHOBOS Au+Au nucl-ex/0210015 nucl-ex/0210015 Systematic errors not shown The “Fragmentation Region” grows with sNN Russell Betts DNP Meeting MSU Oct 2002

  8. Universal Limiting Curve for Particle Production p + p inel. 6% central dN/dh¢ dNch/dh ¢/<Npart/2> PHOBOS Au+Au nucl-ex/0210015 UA5, Z.Phys.C33, 1 (1986) Systematic Errors not Shown Russell Betts DNP Meeting MSU Oct 2002

  9. Centrality Dependence of dNch/dh¢ Results : Limiting Fragmentation vs Centrality PHOBOS Au+Au 0-3% central 200 GeV 35-40% central 19.6 GeV nucl-ex/0210015 Systematic errors not shown  = h – yBeam • Shape Changes with Centrality but Scaling Persists • Full Integral Changes Little with Centrality Russell Betts DNP Meeting MSU Oct 2002

  10. Summary • Systematic Data for Charged Particle Multiplicity over ~ Full Rapidity Range and an Order of Magnitude in sNN. • Data do not Display Growth of Mid Rapidity Plateau as Suggested by Bjorken (Boost Invariant) Scaling. • Scaling Observed in Fragmentation Region the Extent of which Grows with Increasing Energy. • Other Intriguing Features of Data Russell Betts DNP Meeting MSU Oct 2002

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