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Bulk Observables in p-p, d-Au and Au-Au at RHIC

Bulk Observables in p-p, d-Au and Au-Au at RHIC. David Hofman University of Illinois at Chicago For the Collaboration. QCD and High Energy Hadronic Interactions March 28 – April 4, 2004 XXXIXth Recontres de Moriond. Collaboration (February 2004).

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Bulk Observables in p-p, d-Au and Au-Au at RHIC

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  1. Bulk Observables in p-p, d-Au and Au-Au at RHIC David Hofman University of Illinois at Chicago For the Collaboration QCD and High Energy Hadronic InteractionsMarch 28 – April 4, 2004 XXXIXth Recontres de Moriond

  2. Collaboration (February 2004) Birger Back,Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Abigail Bickley, Richard Bindel, Wit Busza (Spokesperson), Alan Carroll, Zhengwei Chai, Patrick Decowski, Edmundo García, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Clive Halliwell, Joshua Hamblen, Adam Harrington, Michael Hauer, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta Iordanova, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Michael Ricci, Christof Roland, Gunther Roland, Joe Sagerer, Helen Seals, Iouri Sedykh, Wojtek Skulski, Chadd Smith, Maciej Stankiewicz, Peter Steinberg, George Stephans, Andrei Sukhanov, Marguerite Belt Tonjes, Adam Trzupek, Carla Vale, Siarhei Vaurynovich, Robin Verdier, Gábor Veres, Edward Wenger, Frank Wolfs, Barbara Wosiek, Krzysztof Woźniak, Alan Wuosmaa, Bolek Wysłouch ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORY INSTITUTE OF NUCLEAR PHYSICS, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGY NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGO UNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER Moriond 2004

  3. Central (head-on) Collisions dNch/dh @ midrapidity 200 GeV Charged Particle Production at RHIC Pseudorapidity =  = Lorentz invariant angle with respect to the beampipe h=-ln tan q/2 0 -1 +1 -2 +2 +3 -3 Beamline not to scale Moriond 2004

  4. A “coffee napkin” Estimate ofEnergy Density at Midrapidity. Look at all produced particles in a Central ‘Head-on’ Collision Dh = 1 Total energy released in Dh=1 is ~ 1000 GeV Max initial overlap volume  Initial Energy Density Estimate, e~ 5 GeV/fm3 Moriond 2004

  5. Gluon Saturation RHIC SPS AGS Charged Particle Density near Midrapidity Central Collisions (for Heavy Ion data) RHIC - combined √sNN (GeV)  “Logarithmic Rise” for AA data, above pp baseline Moriond 2004

  6. ‘PHOBOS’ Bulk Observables ≡ Low pT PHOBOS arXiv:nucl-ex/0401006 Systematic Errors not shown Moriond 2004

  7. “Participant” Scaling Au+Au Collisions p + p Collisions # of participating pairs of nucleons≡ Npart/2 Npart/2= 1 Npart/2~ A Binary “Collision” Scaling # of binary NN collisions ≡ Ncoll L~A1/3 Ncoll= 1 Ncoll~ A4/3 Moriond 2004

  8. Centrality Dependence of Midrapidity Charged Particle Yields 20 200 GeV - |h|<1 Binary Collision(Ncoll) Scaling dN/dh/(Npart/2) 10 p+p Au+Au Participant (Npart) Scaling 0 0 200 <Npart> 400 peripheral central  Au+Au Centrality Dependence allows only about 10% Ncoll Scaling Moriond 2004

  9. Charged Particle Production at Midrapidity p + p Energy and Centrality Dependence Data is normalized by p+p value for each energy. Binary collision scaling 200 GeV Au+Au 130 GeV 19.6 GeV preliminary Participant scaling peripheral central  All RHIC energies show a similar Npart dependence Moriond 2004

  10. Ratios to Help Cancel Systematics Systematics PHOBOS, PRC 65, 061901(R) (2002) 50 40 30 20 10 0 Percentile of Cross Section • Systematics Dominated by Trigger Efficiency/Centrality Determination Ratio (200/130) = 1.14 ± 0.01 (stat) ± 0.05 (syst) Moriond 2004

  11. 200 GeV <Nch>e+e-*(Npart/2) 130 GeV 19.6 GeV Centrality Dependence of Total Charged Particle Production Nch Au+Au Collisions central 200 GeV dN/dh/<1/2 Npart> peripheral central peripheral 19.6 GeV Pseudorapidity • Nch(AuAu) = (Npart/2) Nch(e+e-) Moriond 2004

  12. Pseudorapidity Distribution of Charged Particles in d + Au and p + p Collisions at 200 GeV • p + p at 200 GeV • d + Au at 200 GeV Min-Bias arXiv:nucl-ex/0311009 andSubmitted to PRL PHOBOS Preliminary • PHOBOS can measure down to very low multiplicities. Moriond 2004

  13. central peripheral d+Au Centrality Dependence of dNch/dh Shape (Normalized to Nch so can compare shape change) Npart (15.5) (10.8) (7.2) (4.2) Lines to Guide Eye Only Systematic errors not shown (2.7) • In dAu, particle production shifts to negative rapidity with increasing Npart. Moriond 2004

  14. Participant Scaling in d+Au • Nch(dAu) = (Npart/2) Nch(pp) Moriond 2004

  15. Nch in Au-Au vs. p-p and d-Au @ 200 GeV Au+Au e+e-  Difference in total charged particle production between Au+Au (e+e-) vs. d+Au (pp) at same collision energy Moriond 2004

  16. PHOBOS Au+Au dNch/dh Features of the Data at High Pseudorapidity (h). → Move to rest frame of one nucleus: i.e. h’ = h – ybeam. Moriond 2004

  17. Reminder: Limiting Fragmentation in p+p p + p inel. dN/dh¢ Ansatz: Benecke, Chou, Yang, Yen, Phys. Rev. 188, 2159 (1969) Data: UA5 (Alner et al.), Z.Phys.C33, 1 (1986)  Ansatz: At high collision energy, d2N/dy’dpT and particle mix, reach a limiting value and become independent of energy around beam rapidity. Moriond 2004

  18. Limiting Fragmentation in Au+Au  Growth of the Fragmentation Region with sNN Moriond 2004

  19. Limiting Fragmentation in dAu and pEmulsion Data dAu & pEmulsion per incident nucleon and approx. same Npart Npart Selection: p Em 1 2.4 d Au 1.6 1.6x2.4  Growth of the Fragmentation Region with sNN in d+Au and pEm R. Nouicer, QM ‘04 Moriond 2004

  20. Directed Flow: v1 Elliptic Flow: v2 Charged Particle “Flow”: A Bulk Collective Effect Initial spatial anisotropy z z Reaction plane (YR) y f x y y x x (defines YR) Final momentum anisotropy dN/d(f -YR ) = N0 (1 + 2v1cos (f-YR) + 2v2cos (2(f-YR)) + ... ) py px Moriond 2004

  21. Directed Flow (v1) In Beam Rest Frame In target frame of reference, directed flow exhibits signal consistent with limiting fragmentation  Limiting Fragmentation Behavior in Directed Flow S. Manley, 20th Winter Workshop Moriond 2004

  22. Elliptic Flow (v2) In Beam Rest Frame v2 PHOBOS Preliminaryv2200 PHOBOSv2130 h’  Limiting Fragmentation Behavior in Elliptic Flow S. Manley, 20th Winter Workshop Moriond 2004

  23. Experimental SummaryBulk (charged particle) Observables at RHIC • Scaling of multiplicity data with Npart/2 in Au+Au and d+Au. • Per participant pair, Au+Au reaches e+e- total particle production level at RHIC energies. d+Au reaches p+p level (at the same collision energy). • “Limiting fragmentation” of charged particle multiplicity yields (dN/dh) observed in Au+Au and d+Au at RHIC. • “Limiting fragmentation” of azimuthal angular distribution of charged particles (v1 and v2) observed at RHIC. Moriond 2004

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