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Two-Pion Correlations with @ RHIC Chia-Ming, Kuo National Central University, Taiwan for PHOBOS Collaboration Collaboration Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Abigail Bickley, Richard Bindel, Wit Busza (Spokesperson), Alan Carroll, Zhengwei Chai, Patrick Decowski, Edmundo Garcia, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Stephen Gushue, Clive Halliwell, Joshua Hamblen, Adam Harrington, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta Iordanova, Erik Johnson, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Michael Ricci, Christof Roland, Gunther Roland, Joe Sagerer, Iouri Sedykh, Wojtek Skulski, Chadd Smith, Peter Steinberg, George Stephans, Andrei Sukhanov, Marguerite Belt Tonjes, Adam Trzupek, Carla Vale, Siarhei Vaurynovich, Robin Verdier, Gábor Veres, Edward Wenger, Frank Wolfs, Barbara Wosiek, Krzysztof Woźniak, Alan Wuosmaa, Bolek Wysłouch, Jinlong Zhang ARGONNE NATIONAL LABORATORY INSTITUTE OF NUCLEAR PHYSICS, KRAKOW NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF MARYLAND BROOKHAVEN NATIONAL LABORATORY MASSACHUSETTS INSTITUTE OF TECHNOLOGY UNIVERSITY OF ILLINOIS AT CHICAGO UNIVERSITY OF ROCHESTER Motivation Prediction : First order phase transition leads to a prolonged hadronization time Expectation : Large HBT radii Y (side) 2 Rout (~ x xt ) 2 2 Rside ~ y2 X (out) 2 2 Rout Rside 2 ( )2 if x-t correlation is absent & x～y PHENIX and STAR results show that Rout/Rside ~ 1 at 130 GeV STAR “ The HBT Puzzle “ DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo PHENIX Detector @ 2001 Spectrometer Vertex 1m Octagon Paddle Trigger Counter Ring Counters Cerenkov Counter 137000 Silicon Pad Channels ZDC 12 meters of Beryllium beampipe ZDC DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo Spectrometer & Tracking Reversible 2T magnetic field Two symmetric spectrometer arms Tracking within 10 cm of interaction point – providing a small two-particle inefficiency (~ 25x50 mrad in θ and ψ space) Phi acceptance of 3% each arm Ghost tracks ~ 0.3% p/p is better than 1.5% for p<0.7GeV DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo PID & Spec. Acceptance -- DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo Coulomb Correction “E866” Approximate Coulomb Correction (PRC 66, 54906 (2002)) “Partial” Coulomb Correction Gamow λ = 1 Rinv = 5 fm λ = 1 Rinv = 10 fm Coulomb Correction Coulomb Correction Full-Wave Coulomb Correction Gamow λ = 1 Rinv = 5 fm λ = 0.5 Rinv = 5 fm λ = 0.1 Rinv = 5 fm Qinv (GeV/c) Qinv (GeV/c) 2 3 d r S( r ) ψ ( Coulomb r ) FFull (Q, R) 2 3 d r S( r ) ψ ( Plane r ) 1 λ λ(1 e Q R )FFull (Q, R) 2 FPart (Q, R, λ) DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo 2 (1 λe Q R ) 2 2 Data Sample Cut off the area that two-particle acceptance < 95 % Apply “Partial” Coulomb (λ≠1) correction to mixed pairs PHOBOS 200 GeV preliminary DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo HBT Results C 1 e 2 2 2 2 2 2 2 QO RO QL RL QS RS 2QOQL ROL 0.2<y<1.5 0.15<kT<0.35 15 % most central events Phobos preliminary 200 GeV Au-Au - - Rout 0.540.02 ++ 0.570.03 Rside Rlong R2out-long 5.80.2 5.10.4 6.80.3 4.91.7 5.80.2 4.90.4 7.30.3 4.51.9 Systematic error on radii of 1 fm, on of 0.06 DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo Scaling with Energy -- data ● E895 ○ E866 ■ NA49 ▼ NA44 ◆ WA98 ▲ STAR ● PHOBOS Prelim. Preliminary 200 GeV results are agreed between PHOBOS, STAR & PHENIX DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo Conclusions Using RHIC 2001 run data (Au+Au @ 200 GeV) to analyze HBT correlations HBT radii are similar to RHIC 130 GeV results The HBT puzzle still goes on ….. More Kt bins will come Systematic studies are underway DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo Trigger & Event Selection Negative Negative Cerenkov ZDC Positive Paddles Negative Paddles Au PN Au x Positive Positive Cerenkov ZDC z PP Peripheral • Coincidence between Paddle counters at t = 0 defines a valid collision • Paddle + ZDC timing reject background • Trigger sensitive to 97% of inelastic cross section for Au+Au at 200 GeV ZDC Signal (a.u.) 200 GeV Data Central Paddle signal (a.u.) Npart Analyzing 15% most central events -12 < Vertex Z < 10 cm Two-Particle Acceptance TPA is parameterized by (Δθ,ΔYA) ΔYA = 0 ΔYA = 1 ΔYA = 2 ΔYA = 3 Cut off two-particle acceptance < 95 % Rout/Rside @ 200GeV ● PHOBOS 200 GeV preliminary ★ STAR 200 GeV preliminary ▲ PHENIX 200 GeV preliminary Systematic errors are not shown DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo