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Takafumi Niida for the PHENIX Collaboration JPS meeting, Mar. 2012

Azimuthal HBT measurement of charged pions W ith respect to 3 rd event plane In Au+Au 200GeV collisions a t RHIC-PHENIX. Takafumi Niida for the PHENIX Collaboration JPS meeting, Mar. 2012 . outline. Introduction Motivation Analysis method Current status Summary and Outlook.

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Takafumi Niida for the PHENIX Collaboration JPS meeting, Mar. 2012

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  1. Azimuthal HBT measurement ofcharged pionsWith respect to 3rd event plane In Au+Au 200GeV collisions at RHIC-PHENIX TakafumiNiida for the PHENIX Collaboration JPS meeting, Mar. 2012

  2. outline • Introduction • Motivation • Analysis method • Current status • Summary and Outlook

  3. What is HBT ? • Quantum interference between identical two particles • Powerful tool to explore space-time evolution in HI collisions • HBT can measure the source size at freeze-out,Not whole size But homogeneity region in expanding source P(p1) : Probability of detecting a particle P(p1,p2) : Probability of detecting pair particles assuming gaussian source detector 〜1/R detector

  4. Azimuthal HBT measurement • “Out-Side-Long” system • Source shape at freeze-out is measured relative to 2nd order event plane • Sensitive to “system lifetime” • Related to “momentum anistropy” Rlong: Longtudinal size Rside: Transverse size Rout: Transverse size + emission duration Ros: Cross term between Out and Side Rlong Beam Rside Beam Rout

  5. HBT and Triangular flow • Can we measure triangularity by HBT ? • Answer by Blast Wave model is “Yes” • S.Voloshin at QM2011 • Azimuthal HBT relative to Ψ3 will give usmore detailed information of initial conditions and system evolution • Centrality dependence of v3 is very weak unlike v2 • How about triangularity at freeze-out ? Blast wave model calculation by S.Voloshin at QM11 PRL.107, 252301(2011) vn v2 v3 pT[GeV/c]

  6. Analysis method for HBT R(q): real pairs M(q): mixed pairs q: relative momentum of pair • Correlation function • 3 directions of Ψ3 are not distinguished • Mixed pairs are made by event mixing • Events with similar centrality, zvertex, Ψ2 are used • In this analysis, Should we consider Ψ3 for mixed pairs? • Correction of event plane resolution (U.Heinz et al, PRC66, 044903 (2002)) • Coulomb correctionbySinykov‘s fit funcyion • Includingtheeffectoflonglivedresonancedecay Ψ3

  7. Ψ3 dependence for different mixing conditions side out Ψ3 mixing • Data: Au+Au 200GeV in PHENIX • Charged pion pairs are used • “Ψn” mixing is applied here besides centrality and zvertex • If Ψ3 mixing is not applied, - oscillation of Rside become strong - oscillation of Rout become weak • if both Ψ2&Ψ3 mixing is applied, - Similar to Ψ3 mixing - Is this mixing correct ? →How was Ψ2 dependence ? Ψ2 mixing Δφ=φpair–Ψ3 0-10% 10-20% Ψ2&Ψ3 mixing 20-30% 30-60%

  8. How was Ψ2 dependence ? Ψ2 mixing • If Ψ2 mixing is not applied, - oscillation of Rside become strong - oscillation of Rout become weak • Because flow(v2) will be included in mixed pairs for all azimuth angle ? • Similar tendency with Ψ3 analysis • At least, Ψn mixing will be needed to see Ψn dependence without Ψn mixing out side Δφ=φpair–Ψ2

  9. Ψ3 dependence for different mixing conditions side out Ψ3 mixing • Data: Au+Au 200GeV in PHENIX • Pion pairs are used • “Ψn” mixing is applied here besides centrality and zvertex • If Ψ3 mixing is not applied, - oscillation of Rside become strong - oscillation of Rout become weak • if both Ψ2&Ψ3mixing is applied, - Similar to Ψ3 mixing - Is this mixing correct ? →How was Ψ2 dependence ? • Ψ3mixing wll be needed • Mixed-pairs should be same condition with Real pairs, so Ψ2mixing will be also needed • This isstill “work in progress” Ψ2 mixing Δφ=φpair–Ψ3 0-10% 10-20% Ψ2&Ψ3 mixing 20-30% 30-60%

  10. Comparison with Model AMPT S.Voloshin at QM11 out • Ψ2&Ψ3 mixing result is compared • vs AMPT • n=2Rs and Ro have the opposite sign in oscillation • n=3Rs and Ro have the samesign in oscillation • Same tendency with current result • vs Blast wave model • Different tendency in Rside • But both model says “Need more study” side out side Blast wave model Side Out S.Voloshin at QM11 T=100[MeV],ρ=r’ρmax(1+cos(nφ))

  11. Summary • Azimuthal HBT measurement w.r.t Ψ3 is in progress • Tendency of Rside and Rout oscillation changes by Ψn mixing conditions. • Ψ2 andΨ3 mixing will be needed to see “Ψ3” dependence of HBT radii • Current result is similar to AMPT, and different from Blast wave model. • This is still ”work in progress” • Further study will be done Outlook • Need more mixing study • Acceptance study is ongoing • Any simulation may be needed

  12. Back up

  13. PHENIX Detectors • Vertex, Centrality • Vertex, • BBC, ZDC • Event plane • Reaction Plane Detector(RxNP) • Tracking • Drift Chamber, Pad Chamber • PID by EMCal • Used all sectors in west arm

  14. Out 1D Inv 3D Side Long R.P R.P R.P R.P Correlation function for charged pions • Raw C2 for 30-60% centrality • Solid lines is fit functions

  15. Azimuthal HBT radii for pions • Observed oscillation for Rside, Rout, Ros • Rout in 0-10% has oscillation • Different emission duration between in-plane and out-of-plane? out-of-plane in-plane

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