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System size, energy and  dependence of directed and elliptic flow

System size, energy and  dependence of directed and elliptic flow. Steven Manly (Univ. of Rochester) For the PHOBOS Collaboration. Burak Alver , Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Richard Bindel ,

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System size, energy and  dependence of directed and elliptic flow

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  1. System size, energy and  dependence of directed and elliptic flow Steven Manly (Univ. of Rochester) For the PHOBOS Collaboration S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  2. 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 Collaboration meeting, BNL October 2002 Collaboration meeting in Maryland, 2003 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  3. Paddle trigger Spectrometer arm Octagon Ring counter Vertex detector Flow in PHOBOS S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  4. Flow in PHOBOS Correlate reaction plane determined from azimuthal pattern of hits in one part of detector Subevent A S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  5. Flow in PHOBOS with azimuthal pattern of hits in another part of the detector Subevent B S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  6. Flow in PHOBOS Or with tracks identified in the spectrometer arms Tracks S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  7. Flow in PHOBOS Separation of correlated subevents typically large in  S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  8. Flow in PHOBOS For directed flow we use subevents that are symmetric about =0 Subevent A Subevent B S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  9. Probing collisions with flow • Differential flow has proven to be a useful probe of heavy ion collisions: • Centrality • pT • Pseudorapidity • Energy • System size • Species S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  10. Au-Au – directed flow Au-Au 19.6 GeV h± Au-Au 62.4 GeV h± PHOBOS preliminary PHOBOS preliminary Update of directed flow result first shown at QM2004 Similar (2-subevent) technique Added 62.4 GeV data Confirmed with mixed harmonic analysis 0-40% centrality 0-40% centrality Au-Au 130 GeV h± Au-Au 200 GeV h± PHOBOS preliminary PHOBOS preliminary 0-40% centrality 0-40% centrality See poster by A. Mignerey in Poster 1, section 2, number 47 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  11. Au-Au – elliptic flow 0-40% centrality 0-40% centrality PHOBOS Au-Au, h± PHOBOS Au-Au, h± PHOBOS Au-Au, h± 0-40% centrality PHOBOS Au-Au, h± 0-40% centrality PHOBOS Collaboration, Phys. Rev. Lett. 94 (2005) 122303 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  12. Recent theoretical progress in understanding v2(η). See, for example: • M.Csanád, T.Csörgó, B.Lörstad, Nucl. Phys. A742 (2004) 80 [nucl-th/0310040] • U.Heinz, P.F.Kolb, J.Phys. G30 (2004) S1229 [nucl-th/0403044] • T.Hirano, M.Isse, Y.Nara, AOhnishi, and K Yoshino, nucl-th/0506058 ó Au-Au – elliptic flow 0-40% centrality 0-40% centrality PHOBOS Au-Au, h± PHOBOS Au-Au, h± PHOBOS Au-Au, h± 0-40% centrality PHOBOS Au-Au, h± 0-40% centrality PHOBOS Collaboration, Phys. Rev. Lett. 94 (2005) 122303 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  13. Directed flow – extended longitudinal scaling v1 PHOBOS preliminary h±, Au-Au 0-40% centrality Systematic errors only '=||-ybeam Directed flow exhibits extended longitudinal scaling, i.e., approximate rest frame of nucleus. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  14. Elliptic flow – extended longitudinal scaling v2 Au-Au data, h± 0-40% centrality Systematic errors only '=||-ybeam Elliptic flow exhibits striking extended longitudinal scaling PHOBOS Collaboration, Phys. Rev. Lett. 94 (2005) 122303 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  15. ’=||-ybeam Elliptic flow – extended longitudinal scaling v2 Mid-rapidity, 200 GeV, Au-Au Reached the hydro limit? If so, it is an unfortunate coincidence that we saturate v2 right at the highest energy density we can achieve: no break in slope Au-Au data, h± 0-40% centrality Systematic errors only '=||-ybeam Elliptic flow exhibits striking extended longitudinal scaling PHOBOS Collaboration, Phys. Rev. Lett. 94 (2005) 122303 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  16. Elliptic flow – Cu-Cu results • Differential flow has proven to be a useful probe of heavy ion collisions: • Centrality • pT • Pseudorapidity • Energy • System size • Species S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  17. Elliptic flow – Cu-Cu results Hit based 200 GeV PHOBOS preliminary Cu-Cu, h± Track based 200 GeV Hit based 62.4 GeV PHOBOS preliminary Cu-Cu, h± • Cu flow is large • Track- and hit-based results agree (200 GeV) • ~20-30% rise in v2 from 62.4 to 200 GeV S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  18. Elliptic flow – Cu-Cu results PHOBOS preliminary Cu-Cu, 62.4 GeV, h± 0-40% centrality PHOBOS preliminary Cu-Cu, 200 GeV, h± 0-40% centrality Cu-Cu v2(η) shape reminiscent of Au-Au S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  19. v2 PHOBOS preliminary Cu-Cu, h± '=||-ybeam Elliptic flow – Cu-Cu results Cu-Cu collisions also exhibit extended longitudinal scaling statistical errors only Longitudinal scaling reminiscent of Au-Au S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  20. x System size and eccentricity Standard eccentricity (standard) Centrality measure  Npart Paddle signal, ZDC, etc. MC simulations Expect the geometry, i.e., the eccentricity, of the collision to be important in comparing flow in the Au-Au and Cu-Cu systems What is the relevant eccentricity for driving the azimuthal asymmetry? S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  21. x x System size and eccentricity Standard eccentricity (standard) Participant eccentricity (part) Two possibilities Fluctuations in eccentricity are important for small A. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  22. System size and eccentricity Fluctuations in eccentricity are important for the Cu-Cu system. Must use care in doing Au-Au to Cu-Cu flow comparisons. Eccentricity scaling depends on definition of eccentricity. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  23. Elliptic flow – v2 scaling 1 statistical and systematic errors added in quadrature h± h± • Expect <v2>/<>~ constant for system at hydro limit. • Note the importance of the eccentricity choice. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  24. Elliptic flow – v2 scaling 1 statistical and systematic errors added in quadrature h± h± Given other similarities between Au-Au and Cu-Cu flow, perhaps this is evidence that part is (close to) the relevant eccentricity for driving the azimuthal asymmetry S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  25. Elliptic flow – v2 scaling Expect in “low density limit”. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  26. Elliptic flow – v2 scaling • Caution: we used part for PHOBOS data. Important for Cu-Cu, less critical for Au-Au. • Scale v2() to ~v2(y) (10% lower) • Scale dN/d to be ~dN/dy (15% higher) Approximate “LDL” scaling observed. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  27. Elliptic flow – v2 scaling • Caution: we used part for PHOBOS data. Important for Cu-Cu, less critical for Au-Au. • Scale v2() to ~v2(y) (10% lower) • Scale dN/d to be ~dN/dy (15% higher) Points for STAR, NA49 and E877 data taken from STAR Collaboration, Phys.Rev. C66 (2002) 034904 with no adjustments Approximate “LDL” scaling observed. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  28. Elliptic flow – system dependence PHOBOS preliminary h± PHOBOS preliminary h± 0-50% centrality 0-50% centrality PHOBOS preliminary h± 0-50% centrality Eccentricity difference is important for same centrality selection. V2(pT) for Cu-Cu is similar v2(pT) for Au-Au when scaled by part S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  29. Elliptic flow – system dependence PHOBOS 62.4 GeV h± 0-40% centrality PHOBOS 200 GeV h± 0-40-% centrality preliminary preliminary Statistical errors only Statistical errors only v2 for Cu-Cu is ~20% smaller than v2 for Au-Au plotted 0-40% centrality. Drops another ~20% if scaled by ratio S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  30. Elliptic flow – system dependence PHOBOS 62.4 GeV h± 0-40% centrality PHOBOS 200 GeV h± 0-40-% centrality preliminary preliminary Statistical errors only Statistical errors only This data shows v2 does not scale linearly with A as expected by AMPT (factor of 3) AMPT multi-phase transport model (Chen and Ko, nucl-th/0505044) S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  31. Au-Au 19.6 GeV Au-Au 62.4 GeV PHOBOS preliminary Au-Au 130 GeV Au-Au 200 GeV Conclusions • Au-Au directed flow including the new 62.4 GeV data. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  32. Conclusions • Cu-Cu elliptic flow large. Similar in shape to Au-Au. PHOBOS preliminary Cu-Cu, 62.4 GeV, h± 0-40% centrality PHOBOS preliminary Cu-Cu, 200 GeV, h± 0-40% centrality S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  33. v2 v2 PHOBOS preliminary Cu-Cu, h± PHOBOS Au-Au, h± '=||-ybeam '=||-ybeam Conclusions • Au-Au and Cu-Cu systems exhibit extended longitudinal scaling. No break in evolution as function of ηdue to reaching hydro limit. statistical errors only S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  34. Conclusions • Eccentricity definition very important for small systems. 1 statistical and systematic errors added in quadrature h± h± S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  35. Conclusions • Similarity of Au-Au to Cu-Cu flow and the fact that scaling seems to work for part may imply that part (or something close to it) is the relevant geometric quantity for generating the azimuthal asymmetry. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  36. Conclusions • Au-Au directed flow results updated. • Cu-Cu elliptic flow large. Similar in shape to Au-Au. • Au-Au and Cu-Cu systems exhibit extended longitudinal scaling. No break in evolution as function of ηdue to reaching hydro limit. • Eccentricity definition very important for small systems. • v2(pT) is similar in Au-Au and Cu-Cu systems when part is used. • Similarity of Au-Au to Cu-Cu flow and the fact that scaling seems to work for part may imply that part (or something close to it) is the relevant geometric quantity for generating the azimuthal asymmetry. S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  37. Backup Slides S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  38. Elliptic flow subevent regions Regions used to determine reaction plane and resolution. Cu-Cu, 200 and 62.4 GeV and Au-Au, 19.6, 62.4, 130 and 200 GeV: 0.1<|η|<3.0 (use 0.5<|η|<3.0 and 1.0<|η|<3.0 for systematic studies) S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  39. Directed flow subevent regions Regions used to determine reaction plane and resolution. v1 baseline Au-Au, 19.6, 62.4, 130 and 200 GeV: 1.5<|η|<3.0 and 3.0<|η|<5.0 (use 1.5<|η|<2.5 and 3.5<|η|<5.0 for systematic studies) v1 mixed harmonic Au-Au, 19.6, 62.4, 130 and 200 GeV: 1.5<|η|<3.0 and 3.0<|η|<5.0 for the first harmonic part and 0.1<|η|<3.0 for the second harmonic part S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  40. Au-Au update – directed flow Baseline analysis overlaid with new PHOBOS mixed harmonic analysis Shows non-flow correlations small PHOBOS preliminary h± Au-Au PHOBOS preliminary h± Au-Au PHOBOS preliminary h± Au-Au PHOBOS preliminary h± Au-Au Mixed harmonic method: STAR collaboration, Phys. Rev. C 72 (2005) 014904 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  41. Au-Au update – directed flow • 62.4 GeV results are particularly good due to: • large directed flow • large number of tracks/event • large elliptic flow (for mixed harmonic) 62.4 GeV Au-Au, h± Preliminary PHOBOS and STAR results agree well at 62.4 GeV except at highest || STAR 62.4 GeV results from A.H. Tang (STAR Collaboration), nucl-ex/0409029 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  42. Au-Au update – directed flow 62.4 GeV directed flow comparison STAR 62.4 GeV results from A.H. Tang (STAR Collaboration), nucl-ex/0409029 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  43. Au-Au update – directed flow Comparison of directed flow results at 62.4 GeV Estimated by PHOBOS from weighted average of STAR data in multiple centrality bins Discrepancy at high η possibly due to differences in low momentum cutoff? 62.4 GeV Au-Au, h± We used the centrality dependence of STAR’s results to estimate the STAR results in the 10-50% centrality bin S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  44. Au-Au update – directed flow Comparison of preliminary PHOBOS 200 GeV v1 with published STAR results. Plots identical except for STAR centrality selection. STAR 200 GeV results from Phys. Rev. C 72 (2005) 014904 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  45. Au-Au update – elliptic flow Only statistical errors shown Au+Au data (0-40% central) PHOBOS Collaboration, Phys. Rev. Lett. 94 (2005) 122303 S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  46. Elliptic flow – Cu-Cu results preliminary 200 GeV 15-25% Cu-Cu Statistical errors only preliminary 200 GeV Cu-Cu Statistical errors only Cu-Cu more like Hydro than JAM hadron string cascade model Models from Hirano et al., nucl-th/0506058, probably see more later this session Here JAM uses a 1 fm/c formation time. Hydro (160) has kinetic freezeout temperature at 160 MeV S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

  47. System size and eccentricity Mean eccentricity shown in black Au-Au Cu-Cu PHOBOS-Glauber MC preliminary PHOBOS-Glauber MC preliminary Cu-Cu Au-Au PHOBOS-Glauber MC preliminary PHOBOS-Glauber MC preliminary S. Manly – U. Rochester Quark Matter, Budapest, Hungary - August 2005

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