Event anisotropy measurement in highenergy

1

• Event anisotropy measurement in high-energy
• heavy-ion collisions at RHIC
• 
  ShinIchi Esumi
• 
  Univ. of Tsukuba
• Contents
• flow measurements in PHENIX
• identified hadron v2
• charmed and photon v2
• relation of v2 and jets
• azimuthal angle dependent HBT

2
AuAu collisions in sqrt(sNN)200GeV
with Relativistic Heavy Ion Collider (RHIC) at
BNL
PHENIX
mid-rapidity hadron/electron/ photon
spectrometer Forward-rapidity muon
spectrometer
3
BBC/ZDC centrality Dch/PC1,2,3 tracking Tof
hadron PID Rich electron PID Emcal
electron/photon PID
4
AA
pp
Experimentally, the R.P. is defined by the event
anisotropy by itself, when one uses participants.
5
Reaction plane definition
y
y
Reaction plane
Reaction plane
?i
?2
?1
x
x
?i
plane with the directed moment
plane with the elliptic moment
S wisin(?i)
S wisin(2?i)
tan(?1)
tan(2?2)
S wicos(?i)
S wicos(2?i)
(wi 1 or pT or ET)
6
reaction plane based analysis (geometrical
origin / smeared by resolution) dN / d(?-?true)
C (1 S 2vncos(n(?-?true))) ? azimuthal
angle for particles ?true (or meas.) true
(or measured) reaction plane angle vn
measured anisotropy
parameter vn vn/sR.P.
corrected anisotropy parameter sR.P.
reaction plane
resolution pair wise correlation analysis
(no resolution / larger non-flow effect) Nreal
(Df) / Nmixed(Df) C (1 S 2vn2cos(n(D?)))
Df fi-fj F(Df) A exp(-0.5(Df /swidth)2)
B (12v22cos(2Df)) Gauss term is to account
for some of the non-flow contribution.
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Reaction plane detectors in PHENIX
CNT
Beam-beam counter (BBC) h34 64pmts in each
BBC charged particles
Muon arm Silicon multiplicity (MVD) endcap
MVD
BBC
ZDC/ SMD
collision point
South
North
beam line
Zero Degree Calorimeter Shower-Max
Detector Spectator neutron energy Beam position
two central arms (CNT) h tracking, momentum, PID
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Beam-Beam counter
MIP calibration for each pmt Ring gain
correction Average sin/cos shift
correction removing 4 special pmts Normalized
sumx/y distribution correction Conventional
flattering (shifting angle) correction
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Measurement with the MVD

• The MVD is currently configured as a silicon pad
  detector covering a 1.8z0. Effective h range (with vertex smearing)
  is 1.1

• Geometry
• Each end (North/South) has 12 wedges.
• Each wedge has 12 columns of 21 pads. (6048
  channels total)

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ZDC location in RHIC tunnel
South
North
FHC
ZDC Zero Degree Calorimeter BBC Beam Beam
Counters FHC Forward Hadron Calorimeter
SMD
South tunnel
ZDC
Beams eye view of ZDC
PHENIX here
Blue Beam
Yellow Beam
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Schematic of ZDC module assy
LED flasher
16ch. PMT M16
Shower Maximum Detector (SMD)
Zero Degree Calorimeter (ZDC)
WLS fibers
Naked ZDC module
Clear PPMA fibers
Scintillator strips
Tungsten absorber plates
horizontal-strips vertical-strips
12
SMD1 (South)
SMD2 (North)
Y (cm)
beam spot distribution
X (cm)
X (cm)
FSMD1
FSMD2
(Y-CY)/sY
(X-CX)/sX
(X-CX)/sX
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FSMD1-p vs FSMD2
FBBC1-p vs FBBC2
FSMD-p vs FBBC
back-to-back
back-to-back
spectator neutrons vs ps from participants are
flowing opposite.
directed plane
-p,p
F2BBC1 vs F2BBC2
F2MVD1 vs F2MVD2
F2BBC vs F2MVD
elliptic plane
-p/2,p/2
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mid-rapidity hadron, electron, and photon
spectrometer
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STAR
large acceptance hadron tracking
chamber secondary vertex
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large acceptance with full tracking
reaction plane method 2 particle correlation
method 4th order cumulant method
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pT cut
-p 0 p fparticle-FR.P. (rad)
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indication of v2 saturation at RHIC energy
PHOBOS nucl-ex/0406021
PHENIX Preliminary
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Thermal model with blast-wave
hydro is really good to be truth!! What will
happen with resonances?
Resonance effects are important in single
spectra, but not too much in v2, because of pT
shift of heavy particles having smaller v2 and
linear pT dependence of v2.
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pT shift is the dominant effect compared to the
smearing given by the opening angle.
Phys.Lett. B597 (2004) 328-332, X. Dong
et.al. Phys.Rev. C70 (2004) 024901, V. Greco et.al
Pion deviation is explained by resonance decays
21
stat. error only sys. error 15 (200GeV)
v2 /nquark
62.4 GeV AuAu preliminary 200 GeV AuAu,
charged p,K,p PRL91, 182301 (2003)
p0
preliminary
pT /nquark GeV/c
22
Data prefer quark coalescence / recombination
based picture rather than hydro jet picture
at intermediate pT.
quark coalescence
QGP
hydro jet
recombination fragmentation
23
minimum bias AuAu at ?sNN 200 GeV
Almost NO mass ordering
PHENIX preliminary
Similar effect from the time-difference is seen
in v2
quark hadron flow
SPS
PHENIX preliminary
early freeze-out
some remaining mass ordering
Tfo
24
Hadronic cascade fails in magnitude (too small,
it needs a big push from QGP), but it shows clear
meson / baryon difference.
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hydro jet
recombination fragmentation
Jets dominate the high pT part of spectra.
And they (jets) are suppressed.
v2
PHENIX
STAR
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Converter method
Cocktail subtraction method
Charm quarks are binary scaled (lower pT) or
suppressed (high pT) w.r.t light quarks, but it
could be enhanced and suppressed (looked like
binary scaled). The v2 of charm would give a hint
for the answer to the question.
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Converter method
PHENIX Preliminary
Nuclear modification factor
Cocktail subtraction method
pT (GeV/c)
RAA (2.5 28
nucl-ex/0502009
inclusive ee- v2
charmed ee- v2
If charm quarks also flow, charm quarks are
thermalized and / or suppressed (interact with
matter) similarly to the light quarks.
STAR SQM04
29
run2 AuAu 10 J/ys in PHENIX central arm (ee-)
run4 AuAu 100 times in statistics compared with
run2
Single muon and muon pair in PHENIX muon arm
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Direct photons are enhanced w.r.t. p0 production,
but its just because p0 is suppressed, and the
direct photons are in fact binary scaled.
31
vertical bar stat. error curves, gray box
sys. error
Note Inclusive photon including all of the
decay effect from hadrons
, 200 GeV AuAu
, 200 GeV AuAu
, 200 GeV AuAu
phenix preliminary
phenix preliminary
phenix preliminary
The difference here and the g/p0 ratio will give
us a measure of direct g v2.
pT GeV/c
Direct photons should not have any flow by
definition, but Alternatively g/p0 ratio can be
measured by assuming v2g0.
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The difference here is given by the real flow
(v2).
STAR
2 particle correlation (v2 non-flow)
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charged particle v2
STAR nucl-ex/0409033 non-flow
reduced
v22
v2RP
v2RP
v22
v24
STAR Preliminary
If jet suppression ends somewhere, should v2 go
to zero?
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PHENIX Preliminary
Reac. plane v2 does have less non-flow because of
the h gap. Non-flow are removed in 2 part. corr.
2nd cumulant
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recombination fragmentation
old STAR data
semi-old STAR data
no jet-quenching
36
AuAu 200 GeV
v2 reduction of charged particles in the previous
page could be enlarged by the baryon/meson ratio.
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hadron-hadron correlation (full pT reference)
QM04
1.1 1.0 0.9
AuAu 200GeV PHENIX preliminary
1Another way to get the v2 (v2)2 is given by the
pair correlation
harmonic function fixed to the measured v2
harmonic near-side Far-side Gauss function
fit
harmonic near-side Gauss function fit
pure harmonic function fit
1.1 1.0 0.9
2.5Ways to reduce the jet correlation with
additional Gauss terms
f1-f2 (rad)
0. p
0. p
0. p
A12 (v2)2 cos(2Df) Gauss term
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Is the away-side jet-like? Away-side looks jet
like in pp, but not in central AuAu.
nucl-ex/0404010 0501016
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Associated particles pT distributions
nucl-ex/0501016
STAR preliminary
4 GeV/c
re-distributed lost energy
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Q Are jets source of v2? Q Does reaction zone
make flowing jets?
leading parton
hadrons
Proof of the jet quenching and the source of v2
at high pT
4 pT(asso.) 43
trigger hadron pT3GeV/c
associated hadron pT window
QM04
0in-plane middle out-of-plane
c(Df) arb. unit
0-20
Fitted line shape is given by with
fixed (1)v2(trigger) (2)v2(associated) (3)R.P.
resolution (4)in/out bin width
(nucl-ex/0311007) and one free normalization
parameter fit is done in a limited range shown
20-40
40-90
AuAu 200GeV PHENIX preliminary
hadron-hadron correlation
44
trigger hadron pT3GeV/c
associated hadron pT window
QM04
0c(Df) arb. unit
0-20
20-40
flow subtracted hadron-hadron correlation data
40-90
AuAu 200GeV PHENIX preliminary
hadron-hadron correlation
45
associated hadron pT window
trigger photon pT2GeV/c
QM04
0in-plane middle out-of-plane
c(Df) arb. unit
0-20
Fitted line shape is given by with
fixed (1)v2(trigger) (2)v2(associated) (3)R.P.
resolution (4)in/out bin width
(nucl-ex/0311007) and one free normalization
parameter fit is done in a limited range shown
20-40
40-90
AuAu 200GeV PHENIX preliminary
photon-hadron correlation
46
associated hadron pT window
trigger photon pT2GeV/c
QM04
0c(Df) arb. unit
0-20
20-40
flow subtracted photon-hadron correlation data
40-90
AuAu 200GeV PHENIX preliminary
photon-hadron correlation
47
three curves are fixed by measured v2 and
resolution
coalescence of jet-fragmentation could be one of
the source of v2
flow subtracted pTtrigger(h) 3GeV/c 1pTassociated(h) in-plane pair in between pair out-of-plane pair
h - h
real/mixed
PHENIX preliminary
PHENIX preliminary
0 p
0 p
Df (rad)
Df (rad)
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• The correction for R.P was applied
• Sinyukovs fit
• Fitting by cos and sin function

expected tendencies of sin or cos are seen !
49
geo.
geo. time
cross term
(geo. time)/geo.

• Rs,2/Rs,0, Ro,2/Rs,0 and Ros,2/Rs,0 are larger at
  mid-central than at central.
• Ro,2/Rs,0 , Ros,2/Rs,0 seem to be larger than
  Rs,2/Rs,0
• Rl,2/Rl,0 and the difference (Ro,2/Rs,0 -
  Rs,2/Rs,0 ) seem to be possitive?
• anisotropy in geometry or (maybe more) in
  time/expansion

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Summary quark number scaling in v2 and Rcp quark
degree of freedom / partonic flow jet quenching
/ away side jet suppression binary scaling of
direct photon / heavy quark? chemical
equilibrium in hadron yield strangeness
saturation factor gs 1 thermal equilibrium in
momentum spectra large hadronic expansion and
cooling
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RCP for ? and K0s in d-Au
STAR preliminary
52
?
53
STAR preliminary
3 dAu, 40-100
STAR preliminary
AuAu, 0-5
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• Pairs are divided into 4 ?fbins (width45degree)

q_other
qa(GeV/c)