Measurement of azimuthal anisotropy
and quark number scalingon AuAu200GeV at RHIC-PHENIX
Yoshimasa Ikeda
for the PHENIX collaboration(University of Tsukuba)Azimuthal anisotropy
Spatial anisotropy in noncentral collision provides
azimuthal anisotropy ofparticle emission.

ΦThe large anisotropy is anevidence of the formation ofa hot and dense partonicmatter.

dN∝12 v 2 cos 2Φ−Ψ dΦΨ : reaction plane angle2

Motivation of v2 measurement
Large v2 was observed inRHIC.
The values agreed withhydro-dynamical models.
It suggests rapid
thermalization and quarkflow.
The v2 values aredifferent for each particle.
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v2 on PHENIX-Run7

Run7

Centrality 0 - 60%

Better resolution of “RxP” (< 0.75)
Higher statistical (3.5 billion)

PHENIX. PRL. 99, 052301 (2007)

Run4

Centrality 20 - 60%

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PID in PHENIX
πKp

TOF.W
pT = 1 – 2 GeV

dm2 [GeV2]

EMC + TOF.E
KK continuum

EMC + TOF.E
p-π continuum
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Invariant mass [GeV]

Invariant mass [GeV]Hadron v2 on Run7●●

D v2 is higher than p v2
at pT> 3 GeVΛ v2 is consistent to p v2

Φ v2 is near to meson(π or K) rather thanbaryon (p or Λ) at midpT range (pT= 2 – 5GeV).
arXiv:0710.5795●

arXiv:nucl-th/0308051
PHENIX
PreliminaryCentraity 20 - 60%
●Λ
＊Φ

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KET scaling●●●

KE T =M T −M 0= M P −M 0202
T

They are consistent
between mesons orbaryons.
The values are
determined bycentrality, KET andquark number.
Meson line and baryon
line approach at highKET.
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Quark number and KET scaling●●●Consistent for allparticles on KET andquark number scalingat KET/nq<0.8GeV.
They deviate at highKET/nq
This indicate a changeof particle and v2
production mechanism.
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Nucleon number scalingd2p2dTp
Tv ~2 v , p ~2 p●●

arXiv:nucl-th/0312081●

Run7
preliminaryCentrality 0-60%)■d●

D v2 and p v2 areconsistent on pT/Ascaling.
p v2 and n v2 areconsistent.
The peak of d v2 isexpected at pT=6GeV/c.
Coalescence of p-n or 69quarks?

Summary●The new reaction plane detector worked well.
– We can see rare particles by the good resolution.

●.v2 is depend on nq on KET scaling.
– Consistent for all particles on KET and nq scaling atKET/nq<0.8GeV.

– Φ v2 is same to other meson on KET.
●v2 have no depend on the quark number at high pT range.
– Production

mechanism is different.
● d v and p v are consistent on parton number scaling
22d2
dT

p
2p
Tv ~2 v
p ~2 p10

Back up11

Heavy flavor and J/ψ v2(Run4)(Run7)●●●(Run7)

The data at low pT favor
the models that include
quark level elliptic flow ofcharm.
It could not be judged
whether J/Psi succeeds
the charm flow Because
the poor statistics.
B meson decay becomesa significant source
above 2.5 GeV/c.
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Reaction Plane Detector (RxP)
The reaction plane detector wasinstalled just before Run7 (2007).

35cm

Collision piont

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Correlation effectv2 is over estimated bycorrelation effect.
According toHIJING+PYTHIA, the effectby jet does not have any
problem with η>1.516

Design and Geant simulation
resolution

Detector parameters
were optimized withGeant simulation
Thickness
Scintillator 2cm
Converter 2cm
Φ division

Φ division into 12

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π0 → 2γ (98.8%) cτ=25.1[nm]Acceptance of “RxP”
PHOBOS, PRL. 91, 052303 (2003) RxP measure more particles

and the particles with morelarge v2.
RxP : η = ±1~2.8(blue)
BBC : η = ±3.1~4(red)

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19

Configuration of RxP

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Reaction Plane Detector (RxP)
The reaction plane detector wasinstalled just before Run7 (2007).

35cm

Collision piont

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Reaction Plane Resolutioncos2ΔΨ

●Reaction planeresolution was ~0.4
before the introductionof the reaction plane
detector.
– The observed v2v 2 observe=v 2 real×〈cos2  real−observe 〉11
 v 2~×〈cos 2 real−observe 〉  N

strength is only
less than 40% of
its real value.

– statistical power lessthan 1/6.

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Reaction Plane Resolution on Run7
RxPv2 plane|η| = 1.0 – 2.8 New!

RxPinner |η| = 1.5 – 2.8 New!
RxPouter |η| = 1.0 – 1.5 New!
MPC|η| = 3.0 – 4.0 New!

BBC|η| = 3.1 – 3.9

CNT|η| = 0 – 0.35

SMD|η| > 6v 2 observe=v 2real×〈cos 2real−observe 〉11
 v 2~×〈 cos 2  real− observe 〉 N

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KET and quark number scaling
PHENIX. PRL. 99, 052301 (2007)●●●The values of v2 arein proportion to thenumber of quarks
heavy particle shifts
to high pT
These agree very wellby KET/nq scaling at
low pT range.

KE T = M 2 P 2T −M24