1

Measurements of 1st, 2nd and3rd azimuthal anisotropy in√sNN=200GeV Cu+Au collisions
at RHIC-PHENIX
RHIC-PHENIX実験における√sNN=200GeV
銅・金衝突での1次、2次、3次方位角異方性の測定

Pre-Defense
Oct. 28th 2016

Hiroshi Nakagomi
High Energy Nuclear Physics GroupOutline✓Introduction- Quark Gluon Plasma(QGP)- Azimuthal anisotropy- CuAu collisions✓Experiment/Analysis- PHENIX- centrality, event plane- Simulation✓Results/Discussions- vn at mid, forward/backward rapidities- Initial model study- Theory comparison✓Summary2

Introduction

Introduction3

Quark Gluon Plasma(QGP)

Introduction

4

QGP is a state of nuclear matter!
- extremely high temperature, density !
- consist of asymptotic free quarks and gluons!
- Almost perfect liquid
Predicted phase transition εc and Tc by Lattice QCD calculation!
Tc ~ 170 MeV!
εc ~ 1 [GeV/fm3]

Relativistic Heavy Ion Collider(RHIC)

PHENIX

Introduction

5

Species Energies
Au+Au 200, 130, 62.4GeV39, 27, 22.4GeV
19.6 14.6, 7.7GeV
Cu+Cu 200, 62.4, 22.4GeV
U+U
193GeVCu+Au 200GeV
3He+Au 200GeV
d+Au
200GeV
p+Au
200GeV
p+Al
200GeVp+p510, 500, 200GeV
62.4GeV
Wide range of species and energies
Relativistic heavy ion collision
is unique tool to form QGP
Au+Au 200GeV@RHIC- εBj ~ 5 [GeV/fm3] > εc

Azimuthal anisotropy:Elliptic flow
Initial spatial anisotropy:ε2

zz

y
y

Introduction

6

Momentum anisotropy:v2xx

converted thoughhydrodynamic expansion✓Particle production will have an elliptical azimuthal distribution.
- Initial spatial anisotropy ε2 -> Momentum anisotropy v2- Non-isotropic pressure gradientSensitive to-initial condition(Glauber(nucleon),KLN(gluon)..etc.)-viscosity of QGP (η/s)

Introduction

Azimuthal anisotropy:Directed,Triangular flow
Directed flow

7

Triangular flow

Elliptic flow

Ψ3
Ψ2

Ψ1

Event by event, initial participant fluctuation can lead to-Directed particle production anisotropy v1-Triangular particle production anisotropy v3-v4, v5, v6

vn constrain initial condition & viscosity

Introduction

8v2, v3 theory comparison
Au+Au 200GeVPRL 107. 252301

v2, v3 are sensitive to initial condition and viscosity of QGP- Theoretically, initial condition and viscosity have uncertainty->vn are good constraint of both of themIntroduction9

η dependence of v2 with different initial conditions
Glauber + Hydro

QGP only

Au+Au 200GeV

η=0(θ=π/2)

Rapidityη=-log(θ/2)

yη=-0.88(θ=3π/4)

η=0.88(θ=π/4)x

QGP+hadron fluid

KLN + Hydro

Au+Au 200GeV

Phys.Lett.B636:299-304✓v2(η) depends on initial condition- v2 with KLN > v2 with Glauber- v2 with Glauber reproduce dataz
in mid-central collision- v2 with KLN reproduce datain central collisionRapidity dependence of initial condition

Introduction 10

PhysRevC.90.034915

Pb+Pb 2.76TeV

εn,B<εn,F✓initial geometry has been considered to be
rapidity independent✓Initial conditions on target and projectile nuclei
are not same event
εn (+η) > εn (-η)
vn (+η) > vn (-η)✓ Initial geometry has strong rapidity dependenceεn (η) = αεn (+η) + βεn(-η)

Motivation: Why Cu+Au is analyzed ?

Introduction 11

Multiply-interacting!
nucleons

So far, vn have been studied in symmetric collision systems!
First asymmetric Cu+Au collisions were operated in 2012
Asymmetric initial condition provides!
- Intrinsic triangularity of overlap zone -> larger v3!
- Different left/right pressure gradient -> v1!
- Different Forward/Backward density and geometry-> Rapidity asymmetric vn!
-> Measurements of vn in asymmetric system could be good !
study of initial condition

12

My activity
M1~M2 (2011~2013)

D1(2013~2014)

Repair VTX @BNLJPS Spring & Fall (Talk)
QM2012 (poster)
ATHIC 2012 (Talk)
Au+Au flow analysis using VTX

Repair VTX @BNL
Shift taking & detector expert
for Run 13, Run14

D2(2014~2015)
D2(2014~2015)

D3(2015~2016)

QM2014(Talk)
JPS-DNP(Talk)
Shift taking & detector expert
for Run 14, Run15

D4(2016~)
D4 (2016~)
Cu+Au flow paper is
accepted by PRC

Cu+Au flow analysis

QM2015(Poster)TGSW2015 (Talk)
WWND2016(Talk)

Domestic conference
International conference
Hardware and shift
AnalysisExperiment/Analysis 13

Experiment
Analysis

PHENIX detectors

Experiment/Analysis 14

Trigger, centrality, collision vertex
Event plane-Beam Beam counter(BBC)(3<|η|<4)
Event plane-Zero degree calorimeter-Shower max detector
Charged particle Tracking-Drift Chamber(DC) (|η|<0.35)- Momentum-Pad Chamber(PC) (|η|<0.35)- Hit position-Electro magnetic
calorimeter(EMC) (|η|<0.35)- Hit position

Experiment/Analysis 15

Collision centrality
Spectator

Participant

Bbc

Bbc

✓Fraction of events in terms of
total geometrical cross section-Overlap zone of two nuclei∝ Multiplicity

Spectator✓ Experimentally, overlap zone isclassified by multiplicity in Bbc- Multiplicity in Bbc
Overlap zone∝

10-20%

5-10%
0-5%✓ Each percentile contains same
number of events- Most central collision 0 %- Most peripheral collisions 100%

Experiment/Analysis 16

Anisotropy measurement via Event Plane method
Event plane(EP) method- one of the flow measurement methods- produced particles are measured with respect to EP- EP is the azimuthal direction most particles are emitted to- observed vn is corrected by EP resolution< cos(n[vn =Res{

Elliptic moment

Directed momentyobsn ]) >
obs }
n

Ψ1
φi
x

Ψ2

y
φi

Triangular moment

Ψ3

y
φi

x

x

Experiment/Analysis 17

Event plane detectors and resolutions

PHENIX η acceptance

Event Plane detectors

Res{

obs
n } =< cos(n[

obs
n

-6.5

-4

-3

true
n ]) >-0.35 0.35

3

Smd η>6.5

Bbc 3<η<4

Cnt |η|<0.35-Estimated from EP
correlations(3sub method)

Bbc -4<η<-3

Event Plane resolutiondN/dη
Smd η<-6.5- 2nd, 3rd Event plane- Bbc, Cnt- 1st Event plane- Bbc, Smd

4 6.5

η

vn measurement at Bbc(3<|η|<4 )✓vn is measured using 64 Bbc pmts

Experiment/Analysis 18

pmt- Bbc can not reconstruct tracks- Measured vn include back ground✓Full Geant simulation with PHENIX configuration- Measured vn -> True vn
mes
v
n
true
vn =
Rn

Sim
vn,output
Rn = Simvn,input✓Correction factor Rn- R2 : 0.74
- R3 : 0.66

Simvn,input

Input vn from particle simulationSimvn,output

Output vn from Geant simulation✓Systematic study-dN/dη
- pT spectra- vn (pt)- vn (eta)Systematic sources✓vn at mid-η- East and West arm difference- CNT track cut- Event Plane difference- Event Plane resolution difference✓vn at F/B-η
- Event Plane difference- Geant simulation- dN/dη distribution- pT distribution- pT dependence of vn- η dependence of vn

19

Results/Discussions 20

Results
Discussions-

v1,v2,v3 at mid-η
v2,v3 at F/B -η
Initial condition study
v1,v2,v3 theory comparison

Results/Discussions 21

Charged hadron v1(pT) in Cu+Au collisions✓v1 at mid-rapidity is observed for 10-50%✓Negative v1 indicates high pT particle are
emitted to Au side
-Magnitude decreases from central tomore peripheral events-In peripheral events, Left/Right path
length becomes similar

high pT

low pT ?

Results/Discussions 22

Charged hadron v2(pT) in Cu+Au collisions✓Similar pT and centrality dependence of v2 as seenin symmetric collisions- Strong centrality dependence, magnitude increase from
central to peripheral- Cu+Au v2 is between symmetric Au+Au and Cu+Cu
collisions

Results/Discussions 23

Charged hadron v3(pT) in Cu+Au collisions✓Similar pT and centrality dependence of v3 as seenin symmetric collisions- Weak centrality dependence, magnitude slightly increase
from central to peripheral- Cu+Au v3 shows larger values than Au+Au restuls

24

System size dependence of vn(Npart)

1/ε2✓Cu+Au v2/ε2 is consistent with Au+Au and Cu+Cu results✓Unlike v2, Cu+Au v3 is slightly larger than Au+Au v3- Cu+Au v3 arises from not fluctuations but also intrinsic
triangularity of overlap zone ?
✓Cu+A v3/ε3 is not consistent with Au+Au results- MC-Glauber might not reproduce ε3 correctly

1/ε3Results/Discussions 25

Results
Discussions-

v1,v2,v3 at mid-η
v2,v3 at F/B-η
Initial condition study
v1,v2,v3 theory comparison

Results/Discussions 26

Rapidity dependence of vn in Cu+Au collisions✓In Cu+Au collisions, F/B asymmetry of vn is observed.!
-v2(Au-going) > v2(Cu-going)!
-v3(Au-going) > v3(Cu-going)->caused by different initial geometries in Au and Cu ?
✓Unlike v2 , Au-going v3 in Cu+Au show similar values of Au+Au v3

Results/Discussions 27

System size dependence of vn(Npart) at F/B rapidity

ΨPP
ΨPP

?

✓F/B asymmetry of v2 is consistent that of ε2-εn,Au and εn,Cu are estimated from
Au and Cu participants separately

εn,Au > εn,Cu

vn,Au > vn,Cu ?

Results/Discussions 28

Eccentricity scaling of v2 at F/B rapidityv2/ε2,A(B)

dN/dη

Npart

v2/ε2,A+B✓In both cases, v2/ε2 (Npart) in Au-going side and Cu-going side
are not consistent ->Need take into account different energy ?
✓dN/dη(Au-going) > dN/dη(Cu-going) ->vn(Au-going) >vn(Cu-going)✓Scaled v2/ε2,A+B are consistent between Au-going and Cu-goingResults/Discussions 29

Eccentricity scaling of v3 at F/B rapidity
v3/ε3,A(B)

dN/dη

Npart

v3/ε3,A+B✓In both cases, v3/ε3 (Npart) in Au-going side and Cu-going side
are not consistent✓Scaled v3/ε3,A+B are consistent between Au-going and Cu-going✓F/B asymmetry of vn arise from F/B asymmetry of density(dN/dη)Results/Discussions 30

Results
Discussions-

v1,v2,v3 at mid-η
v2,v3 at large-ηInitial condition study
v1,v2,v3 theory comparison

Results/Discussions 31

v2/ε2 scaling with Glauber and IPGlasma
Mid-η

nucleon basegluon base

F/B-η

✓At-mid η, the v2 scaled with nucleon base model areconsistent among three collision systems✓At-F/B η, the v2/ε2 with gluon base model in Cu+Au is
closer to that in Au+Au

v3/ε3 scaling with Glauber and IPGlasma
Mid-η

nucleon basegluon base

F/B-η

✓At-mid η, the v3 scaled with gluon base model in Cu+Au
is closer to that in Au+Au✓At-F/B η, the v3/ε3 with gluon base model in Cu+Au is
closer to that in Au+Au

32

Results/Discussions 33

Results
Discussions-

v1,v2,v3 at mid-η
v2,v3 at F/B-η
Initial condition study
v1,v2,v3 theory comparison

Parton cascade and hydro vn(pT)Results/Discussions 34

20-30%- Hydro(Bozek):Glauber + hydro- Hydro(Hirano):Glauber + hydro+ hadron cascade- AMPT:Glauber + parton cascade + hadron cascade✓Hydrodynamic reproduce vn✓AMPT model well reproduce v2 and v3 , but shows
opposite sign of v1

Parton cascade and hydro vn(η)!
✓AMPT and Hydro predict the magnitude of v2 at F/B rapidity well
✓AMPT reproduce the magnitude of v3 at F/B rapidity well✓Hydro overestimate the magnitude of v3 at F/B rapidity-Hydro:Smooth longitudinal density+hydro-AMPT:Fluctuated longitudinal density+parton cascade

35

Summary36✓v1 at mid-ηHigh pT particles are emitted to Au side✓v2, v3 at mid-η- Similar centrality and pT dependence as seen in symmetric collisions- Cu+Au v3 is larger than Au+Au results, which might arise from intrinsic
triangularity of overlap zone

✓v2, v3 at F/B-η

- Forward/Backward asymmetry of vn in Cu+Au arise from
Forward/Backward asymmetry of density (dN/dη)✓Initial model study-Glauber model describes mid-rapidity v2 well
-IPGlasma model describes mid-rapidity v3 and preferred at F/B η, whichmight indicate different initial conditions between central and F/B η✓Theory comparison-Parton cascade (AMPT) does not well describe sign of v1

Back Up37

Introduction 38

ηs dependence of εnarXiv:12004.5814v2

Glauber
Pb+Pb✓Longitudinal structure is less understood-Transverse direction can be described by Glauber, CGC…
✓Initial spatial geometry εn(η) are η symmetric- Smooth longitudinal density profile, streak-like structurevn measurement at Bbc(3<|η|<4 )✓vn is measured using 64 Bbc pmts

Experiment/Analysis 39

pmt- Bbc can’t reconstruct tracks- pmt based vn include back ground✓Full Giant simulation with PHENIX configuration- pmt based vn -> track based vn

Sim
v
track
pmt
n,inputvn= Rn ⇤ v n
Rn = Simvn,output✓Correction factor Rn- R2 : 0.73
- R3 : 0.65

✓Systematic study-dN/deta- pT spectra- vn(pt)- vn(eta)Simvn,input
Input vn from particle simulationSimvn,output
Output vn from Giant simulation

Initial spatial anisotropy
Glauber Monte Carlo simulation-Wood Saxon density profile p- collision is occurred, if d < ( nn /⇡)d:distance between nucleons
σnn:total cross section(pp collision)⌦ 2
r cos[n(
✏n =
hr2 i

n,P P )]

↵

⌦ 2
↵
1
1 r sin(n )
[tan
+ ⇡]
n,P P =
2n
hr cos(n )iCentrality dependence of εnε2:CuCu>CuAu~AuAu
ε3:CuAu>AuAu

Experiment/Analysis 40

Results/Discussions 41

System size dependence of v2(Npart) and ε2(Npart)✓v2(Npart) and ε2(Npart) are similar system size dependence- Npart:Number of participants from MC-Glauber- v2(AuAu)>v2(CuAu)>v2(CuCu) ~ ε2(AuAu)>ε2(CuAu)>ε2(CuCu)

Results/Discussions 42

System size dependence of v3(Npart) and ε3(Npart)✓Unlike v2(Npart), no significant system size dependence ofv3(Npart) and ε3(Npart)-The ordering of the magnitude of v3 is reversed with that of ε3- v3 in Cu+Au are almost same or slightly larger than those in
Au+Au-> intrinsic triangularity of asymmetric overlap zone?

Results/Discussions 43

System size dependence of v2 at F/B✓In Cu+Au collisions, F/B asymmetry of v2 is observed.!
-central & peripheral collisions: v2(Au-going) ~ v2(Cu-going) !
-mid-central collisions :v2(Au-going) > v2(Cu-going)!
->caused by different initial geometries in Au and Cu ?

Results/Discussions 44

System size dependence of v3 at F/B✓Weak centrality dependence of v3 is seen for all collision systems- AuAu:same centrality dependence as seen mid η- CuAu: v3 decrease as centrality decrease!
✓In CuAu collisions, v3(Au-going) > v3(Cu-going) for all centrality bins-> Like v2, the different initial geometry cause the different v3 ?

F/B asymmetry of dN/dη

Results/Discussions 45✓Like the vn, the dN/dη in Au-going side is higher✓In 50-60%, the dN/dη in Au-going side andCu-going side are almost same due to similar Npart.

Initial geometry model

Results/Discussions 46

Glauber nucleon

IPGlasmaSmooth structure

Fine structure✓Glauber Monte Carlo model:nucleon base✓Glauber Monte Carlo model:Constituent quark base
PRC 93 024901✓IPGlasma Model : gluon base(CGC), PRC 89, 064908->fineness: gluon base>quark base > nucleon baseModel dependence of 2nd and 3rd Eccentricity

47

v2/e2 at f/b rapidity vs dN/dy

v3/e3 at mid rapidity vs dN/dy

v3/e3 at f/b rapidity vs dN/dyvn vs Npartv2/ε2 scaling at mid-rapidity
Glauber nucleon

Glauber quark

Results/Discussions 52

IPGlasma✓v2 scaled with Glauber model(nucleon,quark) areconsistent among three collision systems✓The deviation is seen in central for IPGlasma model

53

v3/ε3 scaling at mid-rapidity
Glauber nucleon

Glauber quark

IPGlasma✓In Glauber model(nucleon,quark), the deviation isseen at central bin✓In IPGlasma model, AuAu v3/ε3 and CuAu v3/ε3 are close
to each other54v2/ε2 scaling at f/b-rapidity
Glauber nucleon

Glauber quark

IPGlasma✓In Glauber model(nucleon,quark), the deviations
between CuAu and AuAu are seen at central bin✓In IPGlasma model, AuAu v2/ε2 and CuAu v2/ε2 are close
to each other55

v3/ε3 scaling at f/b-rapidity
Glauber nucleon

Glauber quark

IPGlasma✓In Glauber model(nucleon,quark), the deviationis seen from central to mid-central✓In IPGlasma model, AuAu v3/ε3 and CuAu v3/ε3 are close
to each otherParton cascade and hydro v2(η)!
✓AMPT and Hydro predict magnitude ofv2 at F/B rapidity well-Hydro:Smooth longitudinal density+hydro-AMPT:Fluctuated longitudinal density+partoncascade✓Hydro reproduces the ratio of F/B v2- In peripheral collisions, the F/B ratio
becomes constant✓AMPT model over-estimate the ratio

56

Parton cascade and hydro v3(η)✓AMPT show the F/B asymmetry of v3- v3 (Au-going) > v3(Cu-going)->Fluctuated longitudinal density show
larger F/B asymmetry of vn✓Hydrodynamics show weak F/Basymmetry of v3-v3(Au-going) ~ v3(Cu-going)->Smooth longitudinal density show
weaker F/B asymmetry of vn

57

58

Directed flow in comparison to STAR and ALICEPRL 111 232302

PRL 101 252301

Results/Discussions 59

MC-Glauber E-by-E hydro v2, v3 at mid-ηFor both centrality, both value of η/s agree with data

vn:AMPT and Hydrodynamics

60

61

62

Azimuthal anisotropy:Elliptic flow
Initial spatial anisotropy:ε2

zz

y
y

x

Introduction 63

momentum anisotropy:v2

xconverted thoughhydrodynamic expansion

particle production will havean elliptical azimuthal distribution.
- Non-isotropic pressure gradientSensitive to-initial condition(Glauber,KLN..etc.)-viscosity(η/s)

PRL 106.192301

pi, K, p flow

Introduction 64

arXiv:1412.1038

v2,v3 have similar particle dependence
v3 scaled with nq3/2

Introduction 65

Scaling property : quark number scaling

arXiv:1412.1038

v2,v3 have similar particle dependence
v3 scaled with nq3/2

Track identification at CNT(|η|<0.35)

Experiment/Analysis 66

TOF.E and TOF.W are used
-TOF.E : Scintillation counter 130ps-TOF.W : MRPC 95ps

Time of flight method
2

m =p

2

✓

ct
L

◆2

!

1

TOF.E positive particles

Charged pi,K,p-pi/K up to 3GeV
-K/p up to 4GeV

Mass square

m:particle mass, p:momentum, L:flight passc:light velocity, t:time of flight

protonKaon
pion
momentumResults/Discussions
67

Results&
Discussions-

System size dependence
PID vnRapidity dependence
Theory comparison

Identified particle v2 in Cu+Au

Results/Discussions 68

arxiv:1509.07784

Mass ordering at low pT for v2 for all centralities
Baryon and meson splitting at mid-pT is seen

Identified particle v1, v3 in Cu+Au

Results/Discussions 69

arxiv:1509.07784

Same particle dependence of v3 is seen as seen in v2
Mass ordering is also seen for v1- At 1<pT<2.5GeV, Mass ordering is seen
- At low and high pt region, baryon v1 ~ meson v1-Not same trend as seen in v2, v3

Quark Number Scaling of v2

Quark Number Scaling works v2 in CuAu
70

Quark Number Scaling for v3

Quark Number Scaling work v3 in CuAu
71

Comparison to AMPT v2
arxiv:1509.07784

AMPT with 3mb reproduce v2-In 0-30%, up to 2GeV-In 30-60%, up to 1GeVMarch 2nd 2016 WWND H.Nakagomi

72

Comparison to AMPT v3
arxiv:1509.07784

AMPT with 3mb reproduce v3-In 0-30%, up to 2GeV
March 2nd 2016 WWND H.Nakagomi

73

Azimuthal anisotropic flow
In relativistic heavy ion collisions, the azimuthal distributionof produced particles is anisotropic

Anisotropic initial overlap region(εn)
If λ≪R, pressure gradient ΔP becomes anisotropic.
λ=Mean free path R=Size of the system
Less particle production
Smaller pressure gradientAnisotropic particle emission(vn)Expansion to short axis direction
by anisotropic pressure gradientMagnitude of azimuthal anisotropic !
particle emission is evaluated asΨnLarger pressure gradientMore particle emission

vn=<cos(n[ϕ-Ψn])> ellipticity with respect to Ψn74

Flow in symmetric collisions system

PRL 107,252301 

H-31 Poster, Reynollds 75

Experiment/Analysis 76

3sub method

PHENIX η acceptance

Event Plane detectors< cos(n[

obs
n,A

obs
obs
n,B ]) >=< cos(n[ n,Aobs=< cos(n[ n,A= Res{

3

true
true
obs
n + n
n,B ]) >true
truen ]) >< cos(n[ nn,A }Res{n,B }Smd η>6.5-Estimated from EP-6.5 -4-3-0.35 0.35
correlations(3sub method)s
obsobs ]) >< cos(n[ obs<cos(n[
n,A
n,B
n,A
obs
Res{ n,A } =obs ]) >< cos(n[ obsn,Bn,CBbc 3<η<4

Cnt |η|<0.35

Bbc -4<η<-3

Event Plane resolutiondN/dη
Smd η<-6.5- 2nd, 3rd Event plane- Bbc, Cnt- 1st Event plane- Bbc, Smd

4 6.5

η

obs ]) >n,C

obs
n,B ]) >Comparison to PHOBOS:v2

My results are consistent with PHOBOS’s results

77

dNch/dη measurements at Bbc
Like vn measurements, correction factors is estimated fromsingle particle simulationdNch/dη = R * Bbc Charge sum(real)
R = (2/3) / Bbc Charge sum(simulation)+-π/(+-π,π0)

R ~0.5
Systematic source:Different η, pT distributions

Comparison to PHOBOSMy results are consistent with PHOBOS’s results

78

Average vn at Mid-rapidity
How to integrate vn(pT)
Weighted average using pT spectra as weights-pT spectra: PHENIX AuAu
(ppg023)-vn: PHENIX AuAu,CuAu,CuCu(ppg124,132,183)
P< vn >=

dN
i dpT ,i vn (pT,i )P dN
i dpT ,i-vn(pT,i) and dN/dpT,i values are obtained from fitting functionsp0
f (pT ) = A()np 0 + pT

79

Determination of pT spectra in Cu+Cu and Cu+Au
Cu+Cu and Cu+Au spectra are assumed using Au+Au spectra-There no published Cu+Cu and Cu+Au spectra-dNch/dη and <pT> depends on Npart
Procedure

p0
n
f
(p
)
=
A(
)
1. Fit Au+Au spectra withT
p 0 + pT

p0 and n are free parameter
2. Obtain p0 and n as a function of Npart
3. Make pT spectra for Cu+Cu and Cu+Au
using p0(Npart) and n(Npart) for corresponding Npart bins
p0(Npart)n(Npart)p0 (Npart )f (pT , Npart ) = ()n(Npart )p0 (Npart ) + pT

80

Comparison to PHOBOS
|η|<1

|η|<1

My results are consistent with PHOBOS within the error-η range is different, PHOBOS’s results are obtained wider range

pT integration is successfully done81