1 P. Chung Nuclear Chemistry, SUNY, Stony Brook Evidence for a long-range pion emission source in Au+Au Collisions at
P. Chung, SUNY Stony Brook 2 Outline 1. Motivation 2. Brief Review of Correlation analysis methods 3.Data Analysis & Results Correlation functions Source functions Source parameters & dependence (centrality, mT, etc) 4.Conclusion/s
P. Chung, SUNY Stony Brook 3 initial state pre-equilibrium QGP and hydrodynamic expansion hadronization hadronic phase and freeze-out Conjecture of collisions at RHIC : Motivation Which observables & phenomena connect to the de-confined stage? Courtesy S. Bass
P. Chung, SUNY Stony Brook 4 QGP and hydrodynamic expansion One Scenario : Motivation Expectation: A de-confined phase leads to an emitting system characterized by a much larger space-time extent than would be expected from a system which remained in the hadronic phase Increased System Entropy that survives hadronization
P. Chung, SUNY Stony Brook 5 Experimental Setup PHENIX Detector Several Subsystems exploited for the analysis Excellent Pid is achieved
P. Chung, SUNY Stony Brook 6 Cuts Dphi (rad) Dz (cm)
P. Chung, SUNY Stony Brook 7 Cuts Dz (cm) Dphi (rad)
P. Chung, SUNY Stony Brook 8 Analysis Summary Image analysis in PHENIX Follows three basic steps. I. Track selection II. Evaluation of the Correlation Functions (with pair-cuts etc.) III. Imaging of Correlation functions Fits to correlation function Dphi >0.02 dz < 5 cm Dphi >0.01 dz > 5 cm
P. Chung, SUNY Stony Brook 9 Analysis Technique Correlation Function Direct Fits to the Correlation Functions Imaging SourceFunction
P. Chung, SUNY Stony Brook 10 Imaging Technique Technique Devised by: D. Brown, P. Danielewicz, PLB 398:252 (1997). PRC 57:2474 (1998). Inversion of Linear integral equation to obtain source function Source function (Distribution of pair separations) Encodes FSI Correlationfunction Inversion of this integral equation == Source Function Emitting source 1D Koonin Pratt
P. Chung, SUNY Stony Brook 11 Imaging Inversion procedure
P. Chung, SUNY Stony Brook 12 ResultsResults Non Gaussian tail observed in source function PHENIX Preliminary
P. Chung, SUNY Stony Brook 13 Non Gaussian tail observed in source function ResultsResults PHENIX Preliminary
P. Chung, SUNY Stony Brook 14 Non Gaussian tail NOT observed at the AGS ResultsResults PHENIX Preliminary E895
P. Chung, SUNY Stony Brook 15 Correlation Fits Parameters of the source function Minimize Chi-squared [Parameterized form for S(r)] + convolution with kernel calculated C(q) Measured correlation function
P. Chung, SUNY Stony Brook 16 Extraction of Source Parameters Fit Function (Pratt et al.) This fit function allows extraction of both the short- and long-range components of the source image This fit function allows extraction of both the short- and long-range components of the source image Bessel Functions Radii Pair Fractions
P. Chung, SUNY Stony Brook 17 Input source function recovered Procedure is Robust ! Quick Test - 1
P. Chung, SUNY Stony Brook 18 Fitting correlation functions Kinematics “Spheroid/Blimp” Ansatz Brown & Danielewicz PRC 64, (2001) “spheroid/Blimp” parameters
P. Chung, SUNY Stony Brook 19 Fix R T = R and vary a Source parameters Recovered Sensitivity Tests
P. Chung, SUNY Stony Brook 20 Fix a and vary R Source parameters Recovered Sensitivity Tests
P. Chung, SUNY Stony Brook 21 Spheroid source function yield excellent fits to data ResultsResults PHENIX Preliminary
P. Chung, SUNY Stony Brook 22 Same source functions from different parameterization Comparison of Source Functions
P. Chung, SUNY Stony Brook 23 Short and long-range components of the source Short-range Long-range T. Csorgo M. Csanad
P. Chung, SUNY Stony Brook 24 Short and long-range components of the source T. Csorgo M. Csanad
P. Chung, SUNY Stony Brook 25 Short and long-range components of the source T. Csorgo M. Csanad Core Halo assumption Expt
P. Chung, SUNY Stony Brook 26 Next Steps; 3D imaging/moment fitting Higher l moments angular deformation of source
P. Chung, SUNY Stony Brook 27 Next Steps; 3D imaging/moment fitting Solid proof of principle Simulation results
P. Chung, SUNY Stony Brook 28 First Extensive study of two-pion 1D source First Extensive study of two-pion 1D source images in Au+Au collisions at RHIC Results indicate evidence for non-Gaussian tail Results indicate evidence for non-Gaussian tail Long-range behavior of source function ~ 3x short-range Long-range behavior of source function ~ 3x short-range Centrality dependence of radius parameters and lambda Centrality dependence of radius parameters and lambda Fraction in compatible with simple estimate of omega decay Further detailed 3D analysis in progress to pin-down origin of long-range behavior SummarySummary