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Two-Pion Correlations withTwo-Pion Correlations with @ RHIC @ RHICChia-Ming, KuoChia-Ming, KuoNational Central University, TaiwanNational Central University, Taiwanfor PHOBOS Collaborationfor PHOBOS Collaboration
CollaborationCollaboration
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 BROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGYNATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGO
UNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER
MotivationMotivationPrediction : First order phase transition leads to a prolonged hadronization time Expectation : Large HBT radii
“ “ The HBT Puzzle “The HBT Puzzle “
STARPHENIX
PHENIX and STAR results show that Rout/Rside ~ 1 at 130 GeV
X (out)
Y (side)
22
22
~)~(
yR
txR
side
xout
2222 )( sideout RRif x-t correlation is absent & x ~ y
DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo
Detector @ 2001Detector @ 2001
137000 Silicon Pad Channels
1m
Spectrometer
Octagon
Vertex
Ring CountersPaddle Trigger Counter
Cerenkov Counter
12 meters of Beryllium beampipeZDC
ZDC
DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo
Spectrometer & TrackingSpectrometer & 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. AcceptancePID & Spec. Acceptance
--
DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo
Coulomb CorrectionCoulomb Correction
Gamowλ = 1 Rinv = 5 fmλ = 1 Rinv = 10 fm
Gamowλ = 1 Rinv = 5 fmλ = 0.5 Rinv = 5 fmλ = 0.1 Rinv = 5 fm
Cou
lom
b C
orre
ctio
n
Cou
lom
b C
orre
ctio
n
Qinv (GeV/c) Qinv (GeV/c)
Full-Wave Coulomb Correction “Partial” Coulomb Correction
“E866” Approximate Coulomb Correction
)λe(1R)(Q,)Feλ(1λ1λ)R,(Q,F 22
22
RQFull
RQ
Part
2
Plane3
2Coulomb
3
Full)r(ψ)rS(r d
)r(ψ)rS(r dR)(Q,F
DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo
(PRC 66, 54906 (2002))
Data SampleData Sample
PHOBOS 200 GeV preliminary
Cut off the area that two-particle acceptance < 95 % Apply “Partial” Coulomb (λ≠1) correction to mixed pairs
DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo
HBT ResultsHBT Results
2222222 21 OLLOSSLLOO RQQRQRQRQeC
- - 0.540.02 5.80.2
5.10.4 6.80.3
Rout Rside Rlong
++ 0.570.03 4.90.4 7.30.3
5.80.2
R2out-long
4.91.74.51.9
Phobos preliminary
200 GeV Au-Au0.15<kT<0.35
0.2<y<1.5
Systematic error on radii of 1 fm, on of 0.06
15 % most central events
DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo
Scaling with EnergyScaling with Energy-- data
DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo
Preliminary 200 GeV results are agreed between PHOBOS, STAR & PHENIX
● E895○ E866■ NA49▼ NA44
WA98◆▲ STAR● PHOBOS Prelim.
ConclusionsConclusions
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 SelectionTrigger & Event SelectionNegativ
e Paddles
Positive Paddles
Au Aux
zPPPN
Positive ZDC
Negative ZDC
NegativeCerenkov Positive
Cerenkov
• 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
Paddle signal (a.u.)ZD
C S
igna
l (a.
u.)
Npart
Nsp
e cta
tor=
2 A-N
par t
Central
Peripheral
200 GeV Data
Analyzing 15% most central events -12 < Vertex Z < 10 cm
Two-Particle AcceptanceTwo-Particle Acceptance
ΔYA = 0 ΔYA = 1
ΔYA = 2 ΔYA = 3
TPA is parameterized by (Δθ,ΔYA)
Cut off two-particleacceptance < 95 %
Rout/Rside @ 200GeV Rout/Rside @ 200GeV
Systematic errors are not shown
● PHOBOS 200 GeV preliminary STAR 200 GeV preliminary★
▲ PHENIX 200 GeV preliminary
DNP, APS 2003 Fall Meeting / Chia-Ming, Kuo