Measurement of Direct photon vMeasurement of Direct photon v22

in in √√ssNNNN=200GeV Au+Au collisions at RHIC-PHENIX=200GeV Au+Au collisions at RHIC-PHENIX

1do we measure Direct photon ?

Why

prompt photon

thermal photon

photon formjet fragmentation hadron decay

inclusive photon

direct photon

2 the result of v2 analysis ?

What

Kentaro Miki for the PHENIX Collaboration

Univ. of Tsukubathermal photon v2>0

prompt photon v2=0

hadron decay photon v2>0

p K e

Space (z)

Tim

e

A A

Jets

0.6fm/c

4fm/c

16fm/c

8fm/c

hadron gas　

equilibrated QGP　

thermalization

R=Ninc / N BG

00 to 92 %

R=Ninc / N BG 00 to 20 %

lead scintillator (PbSc)・ energy resolution 　 2.1 8.1 %/ E1/2 [GeV]

lead glass (PbGl)・ energy resolution 0.76 5.95 %/ E1/2 [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

3do we measure Direct photon ?

How

estimate the 0 v2 　

direct photon v2

hadron decay simulation

estimate the inclusive photon v2

annihilationcompton scattering

Bremsstrahlung (energy loss)

negative v2

positive v2

v2 of direct photonis

positive ? negative?or 0 ??

Energy cut (Ecore >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=Ninc / N BG 20 to 40 %

R=Ninc / N BG 40 to 60 %

work in progress

work in progress work in progress work in progress

direct photon v2 is … almost zero within the range of error bars. -> prompt photon is most effective.

direct photon v2 has … centrality dependence. -> but still need to reduce errors more.

If we can reduce these errors especially low pT region,estimation of thermal photon v2 becomes possible.

photon from jet is …