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Elliptic flow of identified hadrons (  /K/p/d) in Au + Au collisions at s NN = 200 GeV

Elliptic flow of identified hadrons (  /K/p/d) in Au + Au collisions at s NN = 200 GeV. Hiroshi Masui for the PHENIX collaboration. Outline. Introduction v 2 (p T ) of identified hadrons  /K/p Centrality dependence Quark Coalescence picture Deuteron v 2 . Summary.

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Elliptic flow of identified hadrons (  /K/p/d) in Au + Au collisions at s NN = 200 GeV

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  1. Elliptic flow of identified hadrons (/K/p/d) in Au + Au collisions at sNN = 200 GeV Hiroshi Masui for the PHENIX collaboration Hiroshi Masui University of Tsukuba

  2. Outline • Introduction • v2(pT) of identified hadrons • /K/p • Centrality dependence • Quark Coalescence picture • Deuteron v2. • Summary Hiroshi Masui University of Tsukuba

  3. Azimuthal anisotropy - Elliptic flow (v2) - Y • Sensitive probe for early stage of heavy ion collisions. • Initial asymmetry in coordinate space  final asymmetry in momentum space. X Py v2 = <cos2>  = tan-1(py/px) Px Hiroshi Masui University of Tsukuba

  4. Analysis methodReaction plane analysis  : azimuthal angle of charged particles  : azimuthal angle of reaction plane v2 : strength of elliptic flow pattern Target Projectile Reaction plane b:impact parameter Hiroshi Masui University of Tsukuba

  5. Reaction plane determination • Reaction plane is determined at BBC (3<||<4). • 3 units of rapidity away from the mid-rapidity. Less non-flow contribution  : azimuthal location of each PMT w : weight  : azimtuthal angle of reaction plane Hiroshi Masui University of Tsukuba

  6. Hadron identification • Time of flight •  = /8, || < 0.35 • Timing resolution TOF ~ 115 ps • PID in m2 vs momentum space •  : 0.2 < pT < 3.0 GeV/c • K : 0.4 < pT < 3.0 GeV/c • P : 0.6 < pT < 4.0 GeV/c Hiroshi Masui University of Tsukuba

  7. v2(pT) of identified hadrons Minimum bias sNN = 200 GeV • pT < 2.0 GeV/c • v2() > v2(K) > v2(p) • Consistent with calculation of hydrodynamical model. • pT > 2.0 GeV/c • v2(p) > v2(), v2(K) • Clear departure from hydrodynamical behavior is observed. • Saturation at intermediate pT. Hiroshi Masui University of Tsukuba

  8. Centrality dependence of v2(pT) • Same trend can be seen in all centrality bins. • v2(baryon) > v2(meson) @ intermediate pT. Hiroshi Masui University of Tsukuba

  9. Model predictionQuark Coalescence Model D. Molnar, S.A. Voloshin, nucl-th/0302014 Hiroshi Masui University of Tsukuba

  10. Quark Coalescence picture • Scaled by the number of constituent quarks. • v2 v2/nquark • pT  pT/nquark • Remove mass dependence @ intermediate pT. • Mass dependence @ low pT. • Hydro.,  feed down. More studies are needed @ higher pT. Minimum bias sNN = 200 GeV Hiroshi Masui University of Tsukuba

  11. Deuteron v2(pT) PHENIX PRELIMINARY PHENIX PRELIMINARY • v2(/K/p) > v2(d) at pT = 1 – 2 GeV/c. Quark Coalescence works for d, dbar • But statistical error is too large. Need more statistics. Minimum bias sNN = 200 GeV Hiroshi Masui University of Tsukuba

  12. High pT upgrade @ PHENIX Integration Volume PMT Aerogel (11x22x11 cm^3) • Aerogel Cherenkov Counter (n=1.0114) • Aerogel together with TOF can extend the PID capability up to 10 GeV/c !. 160 Cells PMT Rφ Ｚ Hiroshi Masui University of Tsukuba

  13. Summary • Elliptic flow (v2) of identified hadrons (/K/p/d) has been measured at PHENIX. • Different behavior for different particle species. • Consistent with hydrodynamical model (pT < 2.0 GeV/c). • Deviate hydro. and saturation (pT > 2.0 GeV/c). • Qualitatively agreement with Quark Coalescence scenario in intermediate pT region. • An indication that v2 of measured hadrons is already established in a quark-matter phase. • Higher pT data will be available in the next Run. • Detailed study at intermediate to high pT region. Hiroshi Masui University of Tsukuba

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