Report

Azimuthal HBT measurement of charged pions With respect to 3rd event plane In Au+Au 200GeV collisions at RHIC-PHENIX Takafumi Niida for the PHENIX Collaboration JPS meeting, Mar. 2012 outline Introduction Motivation T . Niida Summary and Outlook 2 Current status JPS Mar. 2012 Analysis method What is HBT ? Quantum interference between identical two particles Powerful tool to explore space-time evolution in HI collisions 〜1/R JPS Mar. 2012 assuming gaussian source p1 detector p2 detector 3 P(p1) : Probability of detecting a particle P(p1,p2) : Probability of detecting pair particles q p1 p2 p1 p 2 kT 2 q side kT , qout // kT T . Niida HBT can measure the source size at freeze-out, Not whole size But homogeneity region in expanding source Azimuthal HBT measurement “Out-Side-Long” system 2 2 C2 =1+ l exp(-Rinv qinv ) 2 2 2 2 2 2 =1+ l exp(-Rside qside - Rout qout - Rlong qlong - 2Ros2 qside qout ) Rside Sensitive to “system lifetime” Related to “momentum anistropy” Beam T . Niida Source shape at freeze-out is measured relative to 2nd order event plane JPS Mar. 2012 Rout 4 Rlong: Longtudinal size Rside: Transverse size Rout: Transverse size + emission duration Ros: Cross term between Out and Side HBT and Triangular flow Can we measure triangularity by HBT ? Answer by Blast Wave model is “Yes” S.Voloshin at QM2011 Y3 Y2 Azimuthal HBT relative to Ψ3 will initial conditions and system evolution vn PRL.107, 252301(2011) v2 T . Niida How about triangularity at freeze-out ? v3 pT[GeV/c] 5 Centrality dependence of v3 is very weak unlike v2 Blast wave model calculation by S.Voloshin at QM11 JPS Mar. 2012 give us more detailed information of Analysis method for HBT Correlation function R(q): real pairs M(q): mixed pairs 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 correction by Sinykov‘s fit funcyion Including the effect of long lived resonance decay Ψ3 JPS Mar. 2012 q: relative momentum of pair T . Niida R(q) C2 = M (q) C 2 C 2core C 2halo 2 2 2 2 2 2 G exp( Rside q side Rout qout Rlong qlong 2 Ros2 q side qout ) 6 [ (1 G ) F ] [1 ] Ψ3 dependence for different mixing conditions side Data: Au+Au 200GeV in PHENIX if both Ψ2&Ψ3 mixing is applied, 10-20% 20-30% 30-60% Ψ2 mixing JPS Mar. 2012 - oscillation of Rside become strong - oscillation of Rout become weak 0-10% Δφ=φpair–Ψ3 - Similar to Ψ3 mixing - Is this mixing correct ? →How was Ψ2 dependence ? Ψ2&Ψ3 mixing T . Niida If Ψ3 mixing is not applied, Ψ3 mixing 7 Charged pion pairs are used “Ψn” mixing is applied here besides centrality and zvertex out How was Ψ2 dependence ? Ψ2 mixing If Ψ2 mixing is not applied, - oscillation of Rside become strong - oscillation of Rout become weak JPS Mar. 2012 Because flow(v2) will be included in mixed pairs for all azimuth angle ? Similar tendency with Ψ3 analysis T . Niida At least, Ψn mixing will be needed to see Ψn dependence without Ψn mixing out Δφ=φpair–Ψ2 8 side Ψ3 dependence for different mixing conditions side Data: Au+Au 200GeV in PHENIX Ψ3 mixing Pion pairs are used “Ψn” mixing is applied here besides centrality and zvertex 10-20% If Ψ3 mixing is not applied, 20-30% 0-10% 30-60% - oscillation of Rside become strong - oscillation of Rout become weak JPS Mar. 2012 Ψ2 mixing Δφ=φpair–Ψ3 - Similar to Ψ3 mixing - Is this mixing correct ? →How was Ψ2 dependence ? Ψ3 mixing wll be needed Ψ2&Ψ3 mixing T . Niida if both Ψ2&Ψ3 mixing is applied, out This is still “work in progress” 9 Mixed-pairs should be same condition with Real pairs, so Ψ2 mixing will be also needed Comparison with Model Ψ2&Ψ3 mixing result is compared vs AMPT AMPT S.Voloshin at QM11 n=2 Rs and Ro have the opposite sign in oscillation n=3 Rs and Ro have the same sign in oscillation Same tendency with current result out side T . Niida Blast wave model vs Blast wave model Side Different tendency in Rside But both model says “Need more study” Out S.Voloshin at QM11 T=100[MeV], ρ=r’ρmax(1+cos(nφ)) 10 JPS Mar. 2012 side out Summary Azimuthal HBT measurement w.r.t Ψ3 is in progress Tendency of Rside and Rout oscillation changes by Ψn mixing conditions. Ψ2 and Ψ3 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” Need more mixing study Acceptance study is ongoing T . Niida Outlook JPS Mar. 2012 Further study will be done 11 Any simulation may be needed 12 T . Niida JPS Mar. 2012 Back up PHENIX Detectors Vertex, Centrality Vertex, BBC, ZDC Event plane T . Niida Used all sectors in west arm 13 Drift Chamber, Pad Chamber PID by EMCal JPS Mar. 2012 Reaction Plane Detector(RxNP) Tracking 3D Correlation function for1D charged Out Inv Side pions Long R.P Raw C2 for 30-60% centrality Solid lines is fit functions T . Niida R.P JPS Mar. 2012 R.P 14 R.P 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? 15 in-plane T . Niida JPS Mar. 2012 out-of-plane