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Recent Results from

Recent Results from. Mark D. Baker Brookhaven National Laboratory for the collaboration RHIC & AGS Annual Users’ Meeting May 12, 2004. PHOBOS Workshop talks: Gábor Veres - High p T (T 5/11) Conor Henderson - Strangeness (F 5/14). Congratulations again CAD!.

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Recent Results from

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  1. Recent Results from Mark D. Baker Brookhaven National Laboratory for the collaboration RHIC & AGS Annual Users’ Meeting May 12, 2004 PHOBOS Workshop talks: Gábor Veres - High pT (T 5/11) Conor Henderson - Strangeness (F 5/14)

  2. Congratulations again CAD! And thanks to DOE Office of Science (NP)! 62.4 GeV Mark D. Baker

  3. Collaboration (May 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, 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, Sergei Vaurynovich, Robin Verdier, Gábor Veres, Peter Walters, Edward Wenger, Frank Wolfs, Barbara Wosiek, Krzysztof Woźniak, Alan Wuosmaa, 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 Mark D. Baker

  4. The PHOBOS Detector (2004) Au+Au 200 & 62.4 GeV T0 counter 137000 Silicon Pad Channels SpecTrig TOF Paddle Trigger Counter Octagon NIM A 499, 603-623 (2003) Spectrometer Mark D. Baker

  5. Data from last year’s Users’ meeting... RdA Phys. Rev. Lett. 91 (2003) 072302 Centrality 0-20% 1.5 1.0 0.5 AuAu 200 0 0 4 6 2 Transverse momentum (GeV/c) Mid-rapidity, high pT hadron suppression appears to be a final state effect. Mark D. Baker

  6. Acceptance for PID Analyses TOF dE/dx p p K pT (GeV/c) pT (GeV/c) pT (GeV/c) Mark D. Baker

  7. QM04 dAu TOF spectra Not corrected for feed-down Veres et al., QM2004 Mark D. Baker

  8. b y QM04 AuAu HBT Rout Rside R2ol PHOBOS Prelim. Au+Au 200 GeV Rlong NA49 (1998) PbPb 17.2 GeV Holzman et al., QM2004 Mark D. Baker

  9. Scaling I: h’ (or y’ or xF) PHOBOS Au+Au 6% central PHOBOS d+Au & fixed target p+Em dNch/dh ¢/<Npart/2> Systematic errors not shown Nouicer et al., QM2004 Phys. Rev. Lett. 91 (2003) 052303 Mark D. Baker

  10. b v1 PHOBOS Preliminary y h’= h-ybeam 19.6 GeV 130 GeV 200 GeV QM04 AuAu Flow PHOBOS PHOBOS NA49 Belt-Tonjes et al., QM2004 Mark D. Baker

  11. Scaling II: Nch scales with Npart PHOBOS 200 GeV Au+Au PHOBOS Preliminary arXiv:nucl-ex/0301017 Nouicer et al., QM2004 Non-peripheral AuAu is different from pp/dAu at the same sNN (but similar to e+e-) Mark D. Baker

  12. ? ? ? ? Why the 62.4 GeV run? RAA <<1 at 200 and 130 GeV Shown to be final state effect (Au+Au vs. d+Au) Search for the onset of high-pT suppression Mark D. Baker

  13. Au+Au 62.4 GeV pT spectra vs. centrality Corrections: • acceptance • efficiency • feed-down • secondaries • momentum resolution • ghosts • bin width • dead channels PHOBOS Mark D. Baker arXiv:nucl-ex/0405003

  14. Energy dependence of RAA in pT bins arXiv:nucl-ex/0405003 PHOBOS preliminary PHOBOS Mark D. Baker

  15. Centrality measures “Participants” Au+Au b ~ 10.5 fm Npart/2 ~ A Glauber Monte Carlo L~A1/3 Ncoll= # of NN collisions: ~A4/3 “Collisions” Mark D. Baker

  16. 62.4 GeV 200 GeV RAA ratios at 200 and 62.4 GeV (Au+Au) PHOBOS PLB (2004) 578297 arXiv:nucl-ex/0405003 • Large variation of RAA with centrality • <Npart> from 61 to 335 • <Ncoll> from 76 to 820 p+p reference data at 62.4 GeV: ISR SFM, 0.5<η<1 (acceptance correction with PYTHIA) Mark D. Baker

  17. 62.4 GeV PHOBOS 200 GeV RAA at 200 and 62.4 GeV (Au+Au) Npart arXiv:nucl-ex/0405003 Yields normalized by Npart less centrality-dependent Mark D. Baker

  18. Centrality Evolution in Au+Au • Use central A+A as denominator • Scale with 1/<Npart> • Allows comparison between different experiments Mark D. Baker

  19. 62.4 GeV 200 GeV PHOBOS Evolution with centrality… universal?! Mark D. Baker arXiv:nucl-ex/0405003

  20. 62.4 GeV 200 GeV PHOBOS Evolution with centrality… universal?! For b<10.5 fm: Mark D. Baker arXiv:nucl-ex/0405003

  21. 62.4 GeV 200 GeV PHOBOS Evolution with centrality… universal?! For b<10.5 fm: • Energy-independent • Weak function of Npart, pT Mark D. Baker arXiv:nucl-ex/0405003

  22. 62.4 GeV 200 GeV PHOBOS Evolution with centrality… universal?! For b<10.5 fm: arXiv:nucl-ex/0405003 But, varying the beam energy changes: • Initial state: sNN, Ncoll/Npart, Qs(?) • System: , mB, Nch, • Partonic xT, dE/dx Data are simpler than the models! Mark D. Baker

  23. Summary • Another great year for RHIC (& PHOBOS) • dAu results made the cover of PRL • Spectacular AuAu run @ 200 & 62.4 GeV • Record luminosities, uptimes and setup times. • First results from 2004 submitted to PRL • Data are simpler than the models! • Extended region of scaling in h’ • Npart scaling of Nch (with e+e- coefficient) • Centrality & energy dependence of RAANpart factorizes! Mark D. Baker

  24. PHOBOS preliminary 62.4 GeV 200 GeV Evolution with centrality… universal?! Mark D. Baker

  25. RPC vs. pT, PHOBOS and STAR, 200 GeV Npart PLB 578297, 2004 PRL 91, 172302, 2003 Mark D. Baker

  26. Npart RPC vs. pT, STAR 130 and 200 GeV PRL 89, 202301, 2002 PRL 91, 172302, 2003 Mark D. Baker

  27. p+p(p) reference at 62.4 and 200 GeV Z Phys. C 69, 55 (1995) Nucl. Phys. B 207, 1 (1982) Phys. Lett. B 83, 257 (1979) Nucl. Phys. B 335, 261 (1990) Mark D. Baker

  28. Evolution of RdAu withh Mark D. Baker

  29. Participant Scaling? Mark D. Baker

  30. 62.4 GeV 200 GeV Npart Ncoll RPC vs RPC Mark D. Baker

  31. b (fm) Centrality Determination in Au+Au # of Participants (Npart) Paddle Counter Signal <Ncoll> 200 GeV <Npart> b (fm) top 50% of cross-section <Npart> 61 to 335 <Ncoll> 62 GeV <Npart> Mark D. Baker

  32. Ratio of 200/62.4 GeV Spectra Mark D. Baker

  33. Many ways to slice pz Rapidity: Generalized velocity Feynman x: scaled pz Pseudorapidity: ~y: easier to measure Mark D. Baker

  34. Typical Model features • Structure functions • Glauber/multiple collisions/Cronin • Nuclear shadowing • QCD evolution (DGLAP, BFKL, CGC) • pQCD cross-sections (+K factors?) • Energy loss in medium • Parton fragmentation/hadronization • Hadronic rescattering Mark D. Baker

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