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Global Observables from Au+Au, Cu+Cu, d+Au and p+p Collisions at RHIC Energies

Global Observables from Au+Au, Cu+Cu, d+Au and p+p Collisions at RHIC Energies. Rachid NOUICER Brookhaven National Laboratory (BNL). (for PHOBOS Collaboration). PANIC05 Particles and Nuclei International Conference Santa Fe, NM - October 24-28, 2005. PHOBOS Collaboration.

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Global Observables from Au+Au, Cu+Cu, d+Au and p+p Collisions at RHIC Energies

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  1. Global Observables from Au+Au, Cu+Cu, d+Au and p+p Collisions at RHIC Energies Rachid NOUICER Brookhaven National Laboratory (BNL) (for PHOBOS Collaboration) PANIC05 Particles and Nuclei International Conference Santa Fe, NM - October 24-28, 2005

  2. PHOBOS Collaboration Burak Alver, Birger Back,Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Richard Bindel, Wit Busza (Spokesperson), Zhengwei Chai, Vasundhara Chetluru, Edmundo García, Tomasz Gburek, Kristjan Gulbrandsen, Clive Halliwell, Joshua Hamblen, Ian Harnarine, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta Iordanova, Jay Kane,Piotr Kulinich, Chia Ming Kuo, Wei Li, Willis Lin, Constantin Loizides, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Corey Reed, Eric Richardson, Christof Roland, Gunther Roland, Joe Sagerer, Iouri Sedykh, Chadd Smith, Maciej Stankiewicz, Peter Steinberg, George Stephans, Andrei Sukhanov, Artur Szostak, Marguerite Belt Tonjes, Adam Trzupek, Sergei Vaurynovich, Robin Verdier, Gábor Veres, Peter Walters, Edward Wenger, Donald Willhelm, Frank Wolfs, Barbara Wosiek, Krzysztof Woźniak, Shaun Wyngaardt, Bolek Wysłouch ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORY INSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGY NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGO UNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER

  3. Outline What can we learn from Au+Au and Cu+Cu Collisions at RHIC Energies? • What can we learn from charged hadron production in Cu+Cu compared to Au+Au? • What is the interplay between collision centrality (geometry) and collision energy? • How does elliptic flow scale with geometry and density? (See Alice Mignerey’s Talk: session 4, Section I.7). • Summary

  4. 19.6 GeV 62.4 GeV 130 GeV 200 GeV centrality Au+Au Cu+Cu d+Au Pseudorapidity Distributions of Charged Particles New Results from PHOBOS Cu+Cu at 62.4 and 200 GeV There is no evidence for two separate regions “mid-rapidity and fragmentation regions” in any of the RHIC energies “Continuous distributions”

  5. 19.6 GeV 62.4 GeV 130 GeV 200 GeV centrality Au+Au Cu+Cu d+Au Pseudorapidity Distributions of Charged Particles We define the mid-rapidity region: |h| < 1 • PHOBOS references for the data: • Au+Au : PRL 91, 052303 (2003) PRC: nucl-ex/0509034 • d+Au : PRL 93, 082301 (2004) • Cu+Cu : QM2005: e-Print nucl-ex/0510042

  6. Au+Au, Pb+Pb and p(p)+ p Collisions Particle Density at Mid-rapidity |h| < 1 Interplay Between Collision Energy and System Size Au+Au : PRL 91, 052303 (2003) PRC: nucl-ex/0509034

  7. Particle Density at Mid-rapidity |h| < 1 Interplay Between Collision Energy and System Size Au+Au, Pb+Pb, Cu+Cu and p(p)+ p Collisions Au+Au : PRL 91, 052303 (2003) PRC: nucl-ex/0509034 Cu+Cu: QM2005: e-Print nucl-ex/0510042

  8. Particle Density at Mid-rapidity |h| < 1 Interplay Between Collision Energy and System Size Au+Au, Pb+Pb, Cu+Cu and p(p)+ p Collisions In symmetric collisions Nucleus-Nucleus: it seems the density per nucleon doesn’t depend on the size of the two colliding nuclei but it depends on the colliding energy Au+Au : PRL 91, 052303 (2003) PRC: nucl-ex/0509034 Cu+Cu: QM2005: e-Print nucl-ex/0510042

  9. Similarity Between Cu+Cu vs Au+Au Collisions dN/d in Cu+Cu vs Au+Au Collisions at Similar Npart 200 GeV 62.4 GeV Cu+Cu Preliminary 3-6%, Npart = 100 Cu+Cu Preliminary 3-6%, Npart = 96 Au+Au 35-40%, Npart = 99 Au+Au 35-40%,Npart = 98 Unscaled dN/d very similar for Au+Au and Cu+Cu at same Npart

  10. Similarity Between Cu+Cu vs Au+Au Collisions dN/d in Cu+Cu vs Au+Au Collisions at Similar Npart This is not coincidence 62.4 GeV 200 GeV Cu+Cu Preliminary 15-25%, Npart = 61 Cu+Cu Preliminary 15-25%, Npart = 60 Au+Au 45-55%, Npart = 56 Au+Au 45-50%,Npart = 62 For same system size (Npart ), Cu+Cu and Au+Au are very similar.

  11. Charged Particle Production in Forward Regions Extended Longitudinal Scaling “Limiting Fragmentation” Scenario Au+Au/Cu+Cu Collisions In the rest frame of one of the colliding nuclei: Extended longitudinal scalingappears to be independent of energy and size of the colliding nuclei for more central collision over a very large range of ||-ybeam Centrality: 0-6%

  12. Charged Hadron pT Spectra (Rapidity Range: 0.2 < y <1.4) 62.4 GeV 200 GeV Au+Au preliminary preliminary Cu+Cu d+Au • PHOBOS references for the data: • Au+Au: PRL 94, 082304 (2005), • PLB 578, 297 (2004) • d+Au: Phys. Rev. Lett 91, 072302 (2003) • Cu+Cu : QM2005: e-Print nucl-ex/0510042

  13. Au+Au Similarity Between Cu+Cu vs Au+Au Collisions Nuclear Modification Factor vs Npart 200 GeV Au+Au: PRL 94, 082304 (2005), PLB 578, 297 (2004)

  14. Cu+Cu preliminary Au+Au Similarity Between Cu+Cu vs Au+Au Collisions Nuclear Modification Factor vs Npart 200 GeV Au+Au: PRL 94, 082304 (2005), PLB 578, 297 (2004) Cu+Cu: G. Roland Talk QM2005, e-Print nucl-ex/0510042

  15. Cu+Cu preliminary Au+Au Similarity Between Cu+Cu vs Au+Au Collisions Nuclear Modification Factor vs Npart 62.4 GeV Cu+Cu: G. Roland Talk QM2005, e-Print nucl-ex/0510042 Au+Au: PRL 94, 082304 (2005)

  16. p/p ratio very similar in Cu+Cu and Au+Au Similarity Between Cu+Cu vs Au+Au Collisions Anti-proton/proton Ratio

  17. Factorization What is the interplay between collision centrality (geometry) and collision energy?

  18. PHOBOS HIJING 200/19.6 Saturation 200/62.4 200/130 Cu+Cu preliminary Au+Au Interplay Between Collision Centrality (Geometry) and Collision Energy Factorization of Particle Density at Mid-rapidity (|h|<1) PHOBOS Au+Au Cu+Cu preliminary We observe Energy/Centrality Factorization. Is this factorization an initial state effect?

  19. Interplay Between Collision Centrality (Geometry) and Collision Energy Factorization in pT at Mid-rapidity Ratio of charged hadron yields in 200 GeV to 62 GeV <pT> = 0.25 GeV/c <pT> = 1.25 GeV/c <pT> = 2.5 GeV/c <pT> = 3.88 GeV/c <pT> = 3.38 GeV/c Energy/Centrality factorization up to pT ≈ 4 GeV/c for Npart > 40 Au+Au: PRL 94, 082304 (2005)

  20. dN/dh (Cu+Cu: 0-6%) = Cu R Au (0-6%) Cu dN/dh (Au+Au: 0-6%) dNFact.(CuCu: x %) = RAu(0-6%) dNMeas.(AuAu: x %) dh dh ? dh dh Au+Au : PRL 93, 082302 (2004) for AuAu Cu+Cu: QM2005, e-Print nucl-ex/0510042 System Size Independence of Pseudorapidity Shapes Factorization of dN/dh Shapes Systematic errors are not shown Au+Au at 200 GeV Cu+Cu at 200 GeV dNFact.(Cu+Cu: x%) = dNMeas.(Cu+Cu: x%) Does this factorization work and can we predict the dN/dh distributions of Cu+Cu based on Au+Au?

  21. System Size Independence of Pseudorapidity Shapes Factorization of dN/dh Shapes 200 GeV It thus appears that dN/dh shapes are independent of the overall size of the colliding nuclei, at least between the Cu+Cu and Au+Au systems studied here.

  22. Summary I Scaling of Hadron Production What we can learn from charged hadron production in Cu+Cu compared to Au+Au? For the same system size (Npart, Ncoll) and at the same energy, Cu+Cu and Au+Au are very similar: • Particle Density • Extended Longitudinal Scaling • Total Multiplicity • Particle Ratio p/p • Nuclear Modification dN/dpT (RAA)

  23. Summary II Geometry and Energy What is the interplay between collision centrality (geometry) and collision energy? Factorization of geometry and energy dependence is observed: • Particle Density at Mid-rapidity (|h|<1) • pT spectra • dN/dh Shapes Do these “Scaling and Factorization” observations in charged particle production persist to HIC at LHC?

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