Post on 24-Feb-2016
description
transcript
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 CollaborationJPS meeting, Mar. 2012
T . N
iida
J
PS M
ar. 2
012
outline
Introduction Motivation Analysis method Current status Summary and Outlook
2
T . N
iida
J
PS M
ar. 2
012
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
21 ppq
detector
detector
1p
2p
ToutTside
T
kqkq
ppk
//,2
21
)exp(1)(~1
)()(),(
222
21
212
invinvqRq
pPpPppPC
P(p1) : Probability of detecting a particle
P(p1,p2) : Probability of detecting pair particles
3
〜 1/R
assuming gaussian source
T . N
iida
J
PS M
ar. 2
012
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”
4
Rlong: Longtudinal sizeRside: Transverse sizeRout: Transverse size + emission durationRos: Cross term between Out and Side
R longBeam
Rside
Rout
Beam
T . N
iida
J
PS M
ar. 2
012
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 us more detailed information of initial conditions and system evolution
Centrality dependence of v3 is very weak unlike v2
How about triangularity at freeze-out ?
5pT[GeV/c]
vn v2
v3
PRL.107, 252301(2011)
Blast wave model calculationby S.Voloshin at QM11
T . N
iida
J
PS M
ar. 2
012
Analysis method for HBT 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 correction by Sinykov‘s fit funcyionIncluding the effect of long lived resonance decay
6)2exp(
]1[])1([2222222
222
outsideoslonglongoutoutsideside
halocore
qqRqRqRqRG
FGCCC
Ψ3
R(q): real pairs M(q): mixed pairs q: relative momentum of pair
T . N
iida
J
PS M
ar. 2
012
Ψ3 dependence for different mixing conditions
7
Data: Au+Au 200GeV in PHENIXCharged 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
Ψ3 mixing
Ψ2&Ψ3 mixing
side out
0-10%
10-20%
20-30%
30-60%
Δφ=φpair–Ψ3
T . N
iida
J
PS M
ar. 2
012
How was Ψ2 dependence ?
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
side out
Ψ2 mixing
8
without Ψn mixingΔφ=φpair–Ψ2
T . N
iida
J
PS M
ar. 2
012
Ψ3 dependence for different mixing conditions
9
Ψ2 mixing
Ψ3 mixing
Ψ2&Ψ3 mixing
side out 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&Ψ3 mixing is applied,
- Similar to Ψ3 mixing
- Is this mixing correct ?
→How was Ψ2 dependence ?
Ψ3 mixing wll be needed Mixed-pairs should be same condition
with Real pairs, so Ψ2 mixing will be also needed
This is still “work in progress”
0-10%
10-20%
20-30%
30-60%
Δφ=φpair–Ψ3
T . N
iida
J
PS M
ar. 2
012
Ψ2&Ψ3 mixing result is compared vs AMPT
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
vs Blast wave model Different tendency in Rside
But both model says “Need more study”
Comparison with Model
S.Voloshin at QM11
side
out
side out
SideOut
AMPT
Blast wave model
S.Voloshin at QM11T=100[MeV], ρ=r’ρmax(1+cos(nφ)) 10
T . N
iida
J
PS M
ar. 2
012
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”Further study will be done
11
Outlook Need more mixing study Acceptance study is ongoing Any simulation may be needed
T . N
iida
J
PS M
ar. 2
012 Back up
12
T . N
iida
J
PS M
ar. 2
012
13
PHENIX Detectors Vertex, Centrality
Vertex, BBC, ZDC
Event planeReaction Plane Detector(RxNP)
TrackingDrift Chamber, Pad Chamber
PID by EMCalUsed all sectors in west arm
T . N
iida
J
PS M
ar. 2
012
Correlation function for charged pions
Raw C2 for 30-60% centrality Solid lines is fit functions
R.P
R.P
R.P
R.P
1DInv
3DSide Out Long
14
T . N
iida
J
PS M
ar. 2
012
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
out-of-plane
in-plane