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p 0 and Photon v 2 Study in  s NN = 200GeV Au+Au Collisions

p 0 and Photon v 2 Study in  s NN = 200GeV Au+Au Collisions. KANETA, Masashi for the PHENIX Collaboration RIKEN-BNL Research Center. Hisayuki Torii ShinIchi Esumi Saskia Mioduszewski Edouard Kistenev. Overview. Introduction PHENIX Analysis p 0 v 2 Photon v 2 Summary Outlook.

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p 0 and Photon v 2 Study in  s NN = 200GeV Au+Au Collisions

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  1. p0 and Photon v2 Studyin sNN = 200GeV Au+Au Collisions KANETA, Masashi for the PHENIX Collaboration RIKEN-BNL Research Center Hisayuki Torii ShinIchi Esumi Saskia Mioduszewski Edouard Kistenev Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  2. Overview • Introduction • PHENIX • Analysis • p0 v2 • Photon v2 • Summary • Outlook Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  3. Why Event Anisotropy? y z x • Because of sensitive to collision geometry • In low pT(~<2 GeV/c) • Pressure gradient of early stage • Hydrodynamical picture is established • In high pT(>~2 GeV/c) • Energy loss in dense medium (Jet Quenching) • Partonic flow(?) Here we focus on ellipticity of azimuthal momentum distribution, v2 (second Fourier coefficient) Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  4. PHENIX Experiment • Lead Scintillator and Lead Glass EMCs • Gamma measurement (p0gg) • BBCs and ZDCs • Collision centrality determination • BBCs • Reaction plane determination and • Its resolution correction Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  5. BBC in PHENIX South North ⊿η = 3.1 ~ 4.0 ⊿φ = 2π 144.35 cm • inner ring • middlering • outer ring BBC 64 elements Quartz Cherenkov radiator meshed dynode PMT Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  6. PbGl and PbSc EMC’s • 1 Sector = 6x3 Supermodules (SM) • 1 PbSc SM = 12x12 towers • PbSc towers: 5.52 x 5.52 x 33 cm3 (18 X0) • 15552 blocks total • 1 PbSc tower: • 66 sampling  cells • 1.5 mm Pb,  4 mm Sc • Ganged together by penetrating wavelength shifting  fibers for light collection • Readout: FEU115M phototubes • 2 Sectors PbGl • 1 PbGl Sector • 16x12 supermodules (SM) • 1 PbGl SM • 6x4 towers • Separate reference system • 1 FEM • Reads out 2x3 supermodules or 12x12 towers Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  7. Method of p0 and Photon v2 Measurement • Define reaction plane by charged multiplicity on Beam-Beam Counters • Photon • Obtained second harmonic coefficient from <cos[2(f-Fr)]> • p0 • p0 reconstruction and subtract background (combinatorial and the others) • For each pT, azimuthal angle, centrality • Commbine both information • Counting number of p0 as a function of f-Fr and fit by the formula reaction plane angle event anisotropy parameter measured azimuthal angle of the particle vnreal = vnmeasured/ (reaction plane resolution)n Note: the detail of reaction plane definition will be found in nucl-ex/0305013 Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  8. Reaction Plane Defined by BBC’s - p /2 p/2 - p /2 p/2 • BBC north and south (h=3.1-4.0) are used • Resolution calculation • Two sub-events are selected • North and south Correlation of two BBC’s Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  9. Photon and p0 Identification • Requirement for photon • Dead and noisy EMC towers are removed for the analysis • PID cuts: c2<3 for photon probability to shower shape • |TOF| cut to reject hadron • No charged track hit within cluster isolation window • For p0 • Photon ID, plus • Asymmetry cut: |E1–E2| / ( E1+E2) < 0.8 • Combinatorial background is estimated by event mixing • Classes categorized for event mixing • centrality : every 10% • BBC Z Vertex : every 10cm in ±30cm • reaction plane direction in PHENIX detector : 24 bins in ±p Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  10. Example Plots from the p0 v2 Analysis Procedure Invariant mass of gg from same event and mixed event (classed by reaction plane, centrality, vertex position) 200GeV Au+Au After subtraction, there is 2nd component of B.G. in pT<2GeV/c region normalization range for combinatorial B.G. subtraction shape assumed as linear+asym. Gauss 0 0.2 0.4 0.6 mgg [GeV/c2] 0 0.2 0.4 0.6 mgg [GeV/c2] count number of p0 in a range after 2nd B.G. subtraction (not used the fit function) Fit function: (average of p0 count)  ( 1 + 2 v2 cos[2(f - FR)]) Green lines : deviation by error of v2 0 1.0 2.0 3.0 f-FR [rad] Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  11. <v2> vs. Centrality from 200GeV Au+Au Npart 26 46 74 114 167 235 325 Npart 26 46 74 114 167 235 325     phenix preliminary phenix preliminary Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  12. v2 vs. pTvs. Centrality from 200GeV Au+Au The charged p and K v2 are shown only with statistical errors phenix preliminary phenix preliminary }nucl-ex/0305013 Statistical error is shown by error bar Systematic error from p0 count method and reaction plane determination is shown by gray box • Charged p+K v2 consistent with p0v2 in pT<4GeV/c Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  13. v2 vs. pT (Minimum Bias) from 200GeV Au+Au phenix preliminary }nucl-ex/0305013 phenix preliminary • Identified particle v2 up to pT=10GeV/c 36.3106 [events] = 5.3+0.5-0.4 [(mb)-1] Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  14. Comparison with K0S and L (STAR) STAR data from nucl-ex/0306008 Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  15. Quark Coalescence? - - - - • Phys. Rev. Lett. 91 (2003) 092301, D.Molnar and S.A. Voloshin • qqmeson, qqq(qqq)Baryon • How data looks like? • Non-strange and strange meson and baryon seems to be merged around pT/nquark 1-3GeV/c • But we need more statistics to conclude it Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  16. Photon v2 from 200 GeV Au+Au phenix preliminary Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  17. Photon v2 and Hadron v2 • Photon v2 shows similar tendency with p0 • need more statistics to see photon v2 after p0 (and also h) decay effect Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  18. p0 Decay Effect for Photon v2 • Tool is ready Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  19. Summary • p0 v2 at RHIC • First measurement • In pT=1-10 GeV/c • v2 of the highest pT from identified particle • Charged p v2 consistent with p0v2 • In pT=1-3GeV/c • Minimum bias data shows non-zerop0v2 • Up topT~8 GeV/c • Photon v2 • increasing with pT up to ~2GeV/c • and saturated then decreasing(?) • We hope to see photon v2 after decay effect subtraction with more data Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

  20. Outlook • Feature plan of analysis • Using high pT gamma trigger in run2 Au+Au data • We will have about twice statistics in high pT • need to study trigger bias • therefore, present analysis results are from minimum bias trigger events • h v2 will be also available by same method • PHENIX has photon v2 also • Photon v2 after hadron decay effect, especially low pT! • RHIC run4 Au+Au, it will be • Much more statistics • Detail study of v2 shape around pT=2-4GeV/c • Much higher pT • We want to know where is the end of finite v2 in very high pT • Also capability of photon measurement in low pT by conversion finding Masashi Kaneta, RBRC, BNL Collective flow and QGP properties, RIKEN-BNL workshop (2003/11/17-19)

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