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Shengli Huang Vanderbilt University for the PHENIX Collaboration

High p T identified charged hadron v 2 and v 4 in 200GeV AuAu collisions by the PHENIX experiment. Shengli Huang Vanderbilt University for the PHENIX Collaboration. Outline:. Observables and Motivation Analysis methods Results and Discussion Conclusions. reaction plane. beam. x. y.

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Shengli Huang Vanderbilt University for the PHENIX Collaboration

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  1. High pT identified charged hadron v2 and v4 in 200GeV AuAu collisions by the PHENIX experiment Shengli Huang Vanderbilt University for the PHENIX Collaboration

  2. Outline: • Observables andMotivation • Analysis methods • Results and Discussion • Conclusions S.L. Huang QM08

  3. reaction plane beam x y Anisotropic flow v2 and v4 Peter Kolb, PRC 68, 031902 momentum space asymmetry Spatial space asymmetry • Azimuthal correlation with the reaction plane • Built up in the early stage and self-quenched, therefore supply the early information of matter generated in the collision S.L. Huang QM08

  4. Partonic Flow PHENIX,PRL. 99, 052301 (2007) baryon meson • Baryon and meson elliptic flow follow the number of constituent quark scaling as a function of KET. This indicates that partonic flow builds up at RHIC • Where is the break point where the hydro interfaces with jet fragmentation • The medium density and strength of interactions The dynamic range of the • global partonic flow • How about the higher order anisotropic flow such as v4? SL Huang QM08

  5. Star Preliminary V4/(v2)2 ratio • v4 /v22 is a probe of ideal • hydro behavior and related to • the degree of thermalization! • Peter Kolb, PRC 68, 031902 • R.S.Bhalerao et.al PLB 627,49; • Borghini and Ollitrault, PLB642,227 • Hydro dynamics predicts • v4 /v22 ~0.5 • The identified particles • v4/v22 ratio should provide more • detailed information than • that of charged hadron Y.T. Bai QM06 S.L. Huang QM08

  6. How to Coalesce? b) Different momentum space a) Similar momentum space Meson Meson Baryon Baryon : modification factor L.W. Chen, C.M. Ko nucl-th 0602025 • The measurement of meson and baron v4 /v22 ratio • will allow us to extract the partonic v4,q /v2,q2 ratio • To test whether the partons in different momentum • space also can recombine with each other SL Huang QM08

  7. PHENIX in Run 7 • Run 7: • ~4.5B events and around 50% have been used • A new Time of Flight detector (TOFw) has been installed in • the west arm of PHENIX • A new reaction plane detector (RxNP) has been installed in • the 38 cm < |z| < 42 cm alone the beam SL Huang QM08

  8. TOFw and Aerogel Detectors • TOFw intrinsic timing resolution is ~ 75ps • /K can be separated to 2.8 GeV/c and K/p can be separated • to 4.5 GeV/c • 3. Together with Aerogel detector(ACC), we can identify the K to • pT~4 GeV/c and , p to 7 GeV/c SL Huang QM08

  9. Reaction plane Measurements • RxNP: • Two sets of plastic • scintillators positioned • on either side of the • collision vertex • 12 segments in  • 2 segments in  • 1.0 < || < 1.5 • 1.5 < || < 2.8 • BBC: • 3.1<||<3.9 • Both detectors are away from mid-rapidity. Smaller non-flow effect • on the reaction plane measurements • New RxNP detector resolution is around 74% at mid-centrality Sqrt(2*cos(2*(N-S))) SL Huang QM08

  10. Mass ordering of v2 and v4 • V4 has been measured as a • function of pT in different centrality bins for the , K and p • Mass ordering has been observed for both v2 and v4 • Consistent with the hydrodynamics • Poster 166 A.Taranenko S.L. Huang QM08

  11. KET Scaling of v4 P166 A.Taranenko • The v4 follows the KET scaling well for KET < 1 GeV • The number of constituent quark scaling holds for v4 when • KET/nq < 1 GeV. This confirms that matter with partonic degrees • of freedom has been generated at RHIC S.L. Huang QM08

  12. V4/(v2)2 ratio • The ratio of v4/(v2)2 is close to • 0.9 for the , K and p • Mesons and baryons have similar • v4/(v2)2 ratio What can we extract from this measurement? S.L. Huang QM08

  13. Partonic Thermalization ! • Parton v4,q/(v2,q)2~0.5 Perfect Partonic Liquid! • Partons in different momentum space also can • recombine with each other • 3. Interact more frequently and strongly with each • other S.L. Huang QM08

  14. Charged  v2 • Charged  v2 can be measured to • 6 GeV/c. • The results are consistent with • 0 results in the overlap pT region. • All  v2 start to drop at pT ~ 2.5 GeV/c • in the different centrality bins! S.L. Huang QM08

  15. Kaon and Proton v2 • Kaon v2 can be measured to 4 GeV/c and protons v2 can be measured to 6 GeV/c • Proton v2 starts to drop at pT ~ 4 GeV/c SL Huang QM08

  16. Break Point? KET/nq(GeV) KET/nq(GeV) • In the centrality of 20~60%, the , K and p KET scaling seemly begins to • break at KET/nq ~ 1 GeV • More statistics are required for the further investigation • A factor 2 of Run 7 data will come after QM08 SL Huang QM08

  17. Conclusions New time of flight detector(TOFw) of PHENIX runs successfully in Run 7 with 75 ps intrinsic timing resolution. With new TOFw and RxNP detectors, we can measure the identified charged hadrons v2 to pT~6 GeV/c and v4 to 3 GeV/c The number of constituent quark scaling has been observed for v4 for KET/nq < 1 GeV. Mesons and bayrons have similar v4/(v2)2 ratio which is close to 0.9 The parton v4,q/(v2,q)2 ~ 0.5 : perfect partonic liquid Partonic Thermalization The number of constituent quark scaling seemly begins to break for v2 as KET/nq~1GeV at 20~60% centrality: a)The interface between hydro and jet fragmentation b)Quantitative information about density and interaction strength SL Huang QM08

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