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Measurement of Direct photon v Measurement of Direct photon v 2 2 in in √ √ s s NN NN =200GeV Au+Au collisions at RHIC-PHENIX =200GeV Au+Au collisions at RHIC-PHENIX 1 do we measure Direct photon ? Why prompt photon thermal photon photon form jet fragmentation hadron decay inclusive photon direct photon 2 the result of v2 analysis ? What Kentaro Miki for the PHENIX Collaboration Univ. of Tsukuba thermal photon v 2 >0 prompt photon v 2 =0 hadron decay photon v 2 >0 p K e Space (z) Time A A Jets 0.6fm/c 4fm/c 16fm/c 8fm/c hadron gas equilibrated QGP thermalization R=N inc / N BG 00 to 92 % R=N inc / N BG 00 to 20 % lead scintillator (PbSc) ・ energy resolution 2.1 8.1 %/ E 1/2 [GeV] lead glass (PbGl) ・ energy resolution 0.76 5.95 %/ E 1/2 [GeV] || < 0.375 =902 inclusive photon direct photon neutral hadron which have decay mode to photon ( 0 ,,…) hadron decay photon 1.0~3.0 3.0~5.0 5.0~10.0 3 do we measure Direct photon ? How estimate the 0 v 2 direct photon v 2 hadron decay simulation estimate the inclusive photon v 2 annihilati on compton scattering Bremsstrahlung (energy loss) negative v 2 positive v 2 v 2 of direct photon is positive ? negative? or 0 ?? Energy cut (E core >0.2 GeV) shower shape cut ( 2 < 3) EMCal TOF ( TOF < 1.2 ns) charged veto ( pc3hit > 6.5 cm) probe of initial state of collision photon mixed phase R=N inc / N BG 20 to 40 % R=N inc / N BG 40 to 60 % work in progress work in progress work in progress work in progress direct photon v 2 is … almost zero within the range of error bars. -> prompt photon is most effective. direct photon v 2 has … centrality dependence. -> but still need to reduce errors more. If we can reduce these errors especially low p T region, estimation of thermal photon v 2 becomes possible. photon from jet is …
