2. May, 2004 - LANLS. Manly - Univ. of Rochester1 The Information of Flow Steven Manly Univ. of Rochester Los Alamos National Laboratory May 5, 2004 steven.manly@rochester.edu http://hertz.pas.rochester.edu/smanly/ Not a systematic review of historical/RHIC/PHOBOS results. More a personal tour of what I find interesting.

3. May, 2004 - LANLS. Manly - Univ. of Rochester2 Inquiring minds want to know... Yo! What holds it together?

4. May, 2004 - LANLS. Manly - Univ. of Rochester3 What flies out Pattern of debris

5. May, 2004 - LANLS. Manly - Univ. of Rochester4 Quantum Chromodynamics - QCD Similar to QED … But... Gauge field carries the charge q q distance energy density, temperature relative strength asymptotic freedom qq qq confinement q q

6. May, 2004 - LANLS. Manly - Univ. of Rochester5 Why do we believe QCD is a good description of the strong interaction? Deep inelastic scattering: There are quarks. From D.H. Perkins, Intro. to High Energy Physics

7. May, 2004 - LANLS. Manly - Univ. of Rochester6 Why do we believe QCD is a good description of the strong interaction? No direct observation of quarks: confinement

8. May, 2004 - LANLS. Manly - Univ. of Rochester7 Why do we believe QCD is a good description of the strong interaction? P. Burrows, SLAC-PUB7434, 1997 R. Marshall, Z. Phys. C43 (1989) 595 Need the “color” degree of freedom

9. May, 2004 - LANLS. Manly - Univ. of Rochester8 Why do we believe QCD is a good description of the strong interaction? Event shapes e + e -  Z o  qqe + e -  Z o  qqg

10. May, 2004 - LANLS. Manly - Univ. of Rochester9 Why do we believe QCD is a good description of the strong interaction? Measure the coupling P. Burrows, SLAC-PUB7434, 1997

11. May, 2004 - LANLS. Manly - Univ. of Rochester10 Strong interaction is part of our heritage

12. May, 2004 - LANLS. Manly - Univ. of Rochester11 Chiral symmetry breaking: the “other” source of mass qq q QCD vacuum Quark condensate A naïve view … Strongly interacting particles interact with the vacuum condensate … which makes them much heavier than the constituent quark masses.

13. May, 2004 - LANLS. Manly - Univ. of Rochester12

14. May, 2004 - LANLS. Manly - Univ. of Rochester13 Signatures/observables Energy density or number of participants Measured value Strange particle enhancement and particle yields Temperature J/  and  ’ production/suppression Vector meson masses and widths identical particle quantum correlations DCC - isospin fluctuations Flow of particles/energy (azimuthal asymmetries) jet quenching Each variable has different experimental systematics and model dependences on extraction and interpretation MUST CORRELATE VARIABLES

15. May, 2004 - LANLS. Manly - Univ. of Rochester14 “Flow” = patterns in the energy, momentum, or particle density distributions that we use to ferret out clues as to the nature of the collision/matter Reaction plane x z y M. Kaneta To what extent is the initial geometric asymmetry mapped into the final state?

16. May, 2004 - LANLS. Manly - Univ. of Rochester15 Collision region is an extruded football/rugby ball shape Central Peripheral

17. May, 2004 - LANLS. Manly - Univ. of Rochester16 (reaction plane) Flow quantified dN/d(  R ) = N 0 (1 + 2V 1 cos (  R ) + 2V 2 cos (2(  R ) +... )

18. May, 2004 - LANLS. Manly - Univ. of Rochester17 (reaction plane) dN/d(  R ) = N 0 (1 + 2V 1 cos (  R ) + 2V 2 cos (2(  R ) +... ) Directed flow Flow quantified

19. May, 2004 - LANLS. Manly - Univ. of Rochester18 (reaction plane) dN/d(  R ) = N 0 (1 + 2V 1 cos (  R ) + 2V 2 cos (2(  R ) +... ) Elliptic flow Flow quantified

20. May, 2004 - LANLS. Manly - Univ. of Rochester19 (reaction plane) dN/d(  R ) = N 0 (1 + 2V 1 cos (  R ) + 2V 2 cos (2(  R ) +... ) Higher terms Flow quantified

21. May, 2004 - LANLS. Manly - Univ. of Rochester20 b (reaction plane)

22. May, 2004 - LANLS. Manly - Univ. of Rochester21 Flow as an experimental probe  Sensitive to interaction length/cross section/degree of thermalization  Sensitive to very early times and particle velocities since asymmetry is self-quenching  Probes longitudinal uniformity

23. May, 2004 - LANLS. Manly - Univ. of Rochester22  Subevent technique: correlate reaction plane in one part of detector to  asymmetry in track pattern in other part of detector  Correct for imperfect reaction plane resolution -2.0 <  < -0.1 SubE (a)SubE (b) nana nbnb 0.1 <  < 2.0  dependence of the multiplicity Flow: basic method Poskanzer and Voloshin, Phys. Rev. C58 (1998) 1671

24. May, 2004 - LANLS. Manly - Univ. of Rochester23 The PHOBOS Detector (2001) Ring Counters Time of Flight Spectrometer 4  Multiplicity Array - Octagon, Vertex & Ring Counters Mid-rapidity Spectrometer TOF wall for high-momentum PID Triggering - Scintillator Paddles Counters - Zero Degree Calorimeter (ZDC) Vertex Octagon ZDC z y x   Paddle Trigger Counter Cerenkov 1m 137000 silicon pad readout channels

25. May, 2004 - LANLS. Manly - Univ. of Rochester24 Au-Au event in the PHOBOS detector

26. May, 2004 - LANLS. Manly - Univ. of Rochester25 Flow in PHOBOS

27. May, 2004 - LANLS. Manly - Univ. of Rochester26   coverage  Data at 19.6, 62.3, 130 and 200 GeV 1m 2m 5m 01234512345  coverage for vtx at z=0

28. May, 2004 - LANLS. Manly - Univ. of Rochester27 Pixelized detector Hit saturation, grows with occupancy Sensitivity to flow reduced Can correct using analogue energy deposition –or- measure of occupied and unoccupied pads in local region assuming Poisson statistics Poisson occupancy correction

29. May, 2004 - LANLS. Manly - Univ. of Rochester28 Acceptance (phase space) weighting Octagonal detector Require circular symmetry for equal phase space per pixel Pixel’s azimuthal phase space coverage depends on location Relative phase space weight in annular rings = -1

30. May, 2004 - LANLS. Manly - Univ. of Rochester29  z Dilutes the flow signal  Remove Background  Estimate from MC and correct flow signal Non-flow background + Non-flow Backgrounds

31. May, 2004 - LANLS. Manly - Univ. of Rochester30 Background suppression Works well in Octagon  dE (keV) cosh  Background! Technique does not work in rings because angle of incidence is ~90  Beampipe Detector Demand energy deposition be consistent with angle

32. May, 2004 - LANLS. Manly - Univ. of Rochester31   RingsN OctagonRingsP Spec holes Vtx holes

33. May, 2004 - LANLS. Manly - Univ. of Rochester32 Determining the collision point High Resolution extrapolate spectrometer tracks Low Resolution octagon hit density peaks at vertex z position

34. May, 2004 - LANLS. Manly - Univ. of Rochester33   RingsN OctagonRingsP Spec holes Vtx holes Detector symmetry issues where SPEC vertex efficiency highest Most data taken with trigger in place to enhance tracking efficiency

35. May, 2004 - LANLS. Manly - Univ. of Rochester34   RingsN Octagon RingsP Offset vtx method Limited vertex range along z Subevents for reaction plane evaluation  Good azimuthal symmetry  Fewer events, no 19.6 GeV data  Gap between subevents relatively small Technique used for published elliptic flow signal at 130 GeV

36. May, 2004 - LANLS. Manly - Univ. of Rochester35   RingsN OctagonRingsP Full acceptance method Vertex range -10<z<10 Subevents for reaction plane evaluation vary with analysis  Good statistics, 19.6 GeV data available  Gap between subevents large  Requires “hole filling” Technique used for elliptic and directed flow signal at all energies (only directed flow released to date, elliptic flow coming soon)

37. May, 2004 - LANLS. Manly - Univ. of Rochester36 Dealing with the holes   RingsN Octagon RingsP Inner layer of vertex detector fills holes in top and bottom. Must map hits from Si with different pad pattern and radius onto a “virtual” octagon Si layer

38. May, 2004 - LANLS. Manly - Univ. of Rochester37 Dealing with the holes   RingsN Octagon RingsP Fill spectrometer holes by extrapolating hit density from adjoining detectors onto a virtual Si layer. (Actual spec layer 1 is much smaller than the hole in the octagon.)

39. May, 2004 - LANLS. Manly - Univ. of Rochester38   RingsN OctagonRingsP Track-based method Vertex range -8<z<10 Subevents for reaction plane  Momentum analysis  200 GeV data  Gap between tracks and subevents large  Little/no background

40. May, 2004 - LANLS. Manly - Univ. of Rochester39 Elliptic Flow at 130 GeV Phys. Rev. Lett. 89 222301 (2002) (PHOBOS : Normalized Paddle Signal) Hydrodynamic limit STAR: PRL86 (2001) 402 PHOBOS preliminary Hydrodynamic limit STAR: PRL86 (2001) 402 PHOBOS preliminary Thanks to M. Kaneta

41. May, 2004 - LANLS. Manly - Univ. of Rochester40 STAR 130 GeV 4-cumulant STAR 130 GeV 2-cumulant STAR 130 GeV Reaction Plane 5-53% central Preliminary PHOBOS 200 GeV 0-55% central p t (GeV/c) v2v2 Elliptic flow vs p T

42. May, 2004 - LANLS. Manly - Univ. of Rochester41 Elliptic flow vs p T at low p T PRL 91 (2003) 182301 PRL 87 (2001) 182301  Asymmetry largest at early time, expect v 2 to grow with p T  Expect growth to be less for heavier particles … move slower.

43. May, 2004 - LANLS. Manly - Univ. of Rochester42 Jet-quenching: hard parton interacts with medium, which softens the momentum spectrum in A-A relative to pp

44. May, 2004 - LANLS. Manly - Univ. of Rochester43 Slow partons down, sample smaller asymmetry and elliptic flow saturates Elliptic flow vs p T at high p T

45. May, 2004 - LANLS. Manly - Univ. of Rochester44 Molnar and Voloshin, nucl-th/0302014 Partonic energy loss alone leads drop at very large pT and does not account for meson/baryon differences Quark coalescence vs. fragmentation nucl-ex/0306007 nucl-ex/0305013

46. May, 2004 - LANLS. Manly - Univ. of Rochester45 Xhangbu Xu, Quark Matter 2004 Quark coalescence-NCQ scaling  ’s affected by resonance decays? Dong, Esumi, Sorensen, N.Xu, Z,Xu, nucl-th/0403030

47. May, 2004 - LANLS. Manly - Univ. of Rochester46 Elliptic flow vs  width of  bin PHOBOS Preliminary central 3-15% midcentral 15-25% peripheral 25-50% Hit-based method h±h± M. Belt-Tonjes, Quark Matter 2004 Ben’s MVD analysis

48. May, 2004 - LANLS. Manly - Univ. of Rochester47 Track-based Hit-based peripheral 25-50% h ± v2v2  PHOBOS Preliminary Track-based Hit-based midcentral 15-25% h ± v2v2  PHOBOS Preliminary central 3-15% h ± Track-based Hit-based v2v2  PHOBOS Preliminary v2 vs.  200 GeV method comparison

49. May, 2004 - LANLS. Manly - Univ. of Rochester48 T. Hirano Hydro does not model the  dependence well

50. May, 2004 - LANLS. Manly - Univ. of Rochester49 Energy Energy y-y T y Feynman/Bjorken vs. Landau?? P. Steinberg Nucl-ex/0403050

51. May, 2004 - LANLS. Manly - Univ. of Rochester50 Directed flow Charged hadrons 6-55% central AuAu

52. May, 2004 - LANLS. Manly - Univ. of Rochester51 v1v1 PHOBOS Preliminary PHOBOS AuAu √s NN =19.6 GeV NA49 PbPb √s NN =17.2 GeV Phys.Rev.C68, 034903, 2003 6-55% Minimum Bias h±h± ±± 19.6 GeV AuAu & 17.2 GeV PbPb 19.6 GeV AuAu & 17.2 GeV PbPb 

53. May, 2004 - LANLS. Manly - Univ. of Rochester52 Xhangbu Xu, Quark Matter 2004 Directed Flow comparison at 200 GeV Ben’s MVD flow analysis!

54. May, 2004 - LANLS. Manly - Univ. of Rochester53 Examine energy dependence by going into frame of reference of target

55. May, 2004 - LANLS. Manly - Univ. of Rochester54 “Limiting fragmentation” of elliptic flow PHOBOS Preliminary v 2 200 PHOBOS v 2 130

56. May, 2004 - LANLS. Manly - Univ. of Rochester55 Scaled by “Kolb factor” PHOBOS Preliminary v 2 200 PHOBOS v 2 130 “Limiting fragmentation” of elliptic flow

57. May, 2004 - LANLS. Manly - Univ. of Rochester56 Energy y-y T

58. May, 2004 - LANLS. Manly - Univ. of Rochester57 Conclusions P. Steinberg ?  Interaction length is short - early thermalization likely  Hydro/Bjorken/Feynman works well at mid-   Flow gives evidence for partonic energy loss in medium and quark coalescence  Hydro/Bjorken/Feynman(  ) inconsistent with multiplicity and elliptic flow data. Maybe not with directed flow?  Landau(  ) consistent with multiplicity and elliptic flow  No indication of major change in nature of particle production as function of  RHIC results/flow are exciting … and a bit puzzling!

59. May, 2004 - LANLS. Manly - Univ. of Rochester58

60. The end Backup slides follow

61. May, 2004 - LANLS. Manly - Univ. of Rochester60 quarks leptons Gauge bosons u c t d s b e   W, Z, , g, G g Hadrons Baryons qqq qq mesons p = uud n = udd K = us or us  = ud or ud Strong interaction nuclei e atoms Electromagnetic interaction

62. May, 2004 - LANLS. Manly - Univ. of Rochester61 What forces exist in nature? What is a force? How do forces change with energy or temperature? How has the universe evolved? How do they interact?

63. May, 2004 - LANLS. Manly - Univ. of Rochester62 Cumulant Method Measure the Generating function G, event-by-event Statistical average of G,, gives Cumulants generating function % M is charged Multiplicity

64. May, 2004 - LANLS. Manly - Univ. of Rochester63 Cumulant Method Expansion of Cumulants generation function is interesting, especially diagonal terms (See more details in J-Y. Ollitrault) because they are related to flow (global correlation) two-particle correlation, 4-particle, 6-particle correlation, etc..

65. May, 2004 - LANLS. Manly - Univ. of Rochester64 (  ) PHOBOS Preliminary v 2 200 (  ) PHOBOS v 2 130 Minimum Bias h±h± v 2 vs.  at 130 and 200 GeV AuAu (  ) PRL 89, 222301 (2002) Hit-based method (  ) Nucl.Phys. A715 (2003) 611-614

66. May, 2004 - LANLS. Manly - Univ. of Rochester65 y vs.  Get a suppression in the spectra which is largest at low p t and small |  |. It vanishes at large |  | and high p t. Gives the famous dip in multiplicity distribution. If integrating v 2 over pt, get suppression of the lower pt part (where v 2 is small) and the signal should rise.

67. May, 2004 - LANLS. Manly - Univ. of Rochester66 Transformation of spectra from  to y leads to suppression of multiplicity at low p t and low |  | This leads to an enhancement of inclusive v 2 at mid-  P. Kolb, Proc. of 17 th Winter Workshop on Nuclear Dynamics (2001) T. Hirano, BNL-Riken Workshop on Collective Flow and the QGP (Nov. 2003) ~10%

68. May, 2004 - LANLS. Manly - Univ. of Rochester67 Relativistic heavy ions  Two concentric superconducting magnet rings, 3.8 km circum.  A-A (up to Au), p-A, p-p collisions, eventual polarized protons  Funded by U.S. Dept. of Energy $616 million  Construction began Jan. 1991, first collisions June 2000  Annual operating cost $100 million  AGS: fixed target, 4.8 GeV/nucleon pair  SPS: fixed target, 17 GeV/nucleon pair  RHIC: collider, 200 GeV/nucleon pair  LHC: collider, 5.4 TeV/nucleon pair

69. May, 2004 - LANLS. Manly - Univ. of Rochester68 The view from above

70. May, 2004 - LANLS. Manly - Univ. of Rochester69 STAR

71. May, 2004 - LANLS. Manly - Univ. of Rochester70 Au-Au collision in the STAR detector

72. May, 2004 - LANLS. Manly - Univ. of Rochester71 Isometric of PHENIX Detector

73. May, 2004 - LANLS. Manly - Univ. of Rochester72 Brahms experiment From F.Videbœk

74. May, 2004 - LANLS. Manly - Univ. of Rochester73 Central Part of the Detector (not to scale) 0.5m

75. May, 2004 - LANLS. Manly - Univ. of Rochester74 Beamline Terminology: angles

76. May, 2004 - LANLS. Manly - Univ. of Rochester75 Beamline Terminology: angles Pseudorapidity =  = Lorentz invariant angle with repect to the beampipe 0 +1 +2 +3 -2 -3

77. May, 2004 - LANLS. Manly - Univ. of Rochester76 Terminology: angles  = azimuthal angle about the beampipe Beamline

78. May, 2004 - LANLS. Manly - Univ. of Rochester77 “Spectators” Zero-degree Calorimeter “Spectators” Paddle Counter peripheral collisions central collisions N ch N part 6% Terminology: centrality Thanks to P. Steinberg for constructing much of this slide “Participants”

79. May, 2004 - LANLS. Manly - Univ. of Rochester78