Spin Physics at RHIC PHENIX 1.Physics Motivation 2.Accelerator and Detector 3.Result from Run2/Run3 4.What we can do? Atsushi Taketani RIKEN RIKEN Brookhaven

Spin Physics at RHIC PHENIX

1. Physics Motivation

2. Accelerator and Detector

3. Result from Run2/Run3

4. What we can do?

Atsushi Taketani

RIKEN

RIKEN Brookhaven Research Center

2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 2

Physics Motivation


Spin Structure of the Nucleon

q

q

g

u

u

d

pWhat is the origin of the Nucleon Spin?

1/2=(1/2)+G+LQ+LG

By Deep Inelastic Scattering Experiment : Quark Spin ~ 0.2-0.3 G : Gluon Spin~ 0 - 2

LQ,LG : Orbital angular momentum ~ ?

Polarized proton Collider Experiment


General Idea of Measurement

A

B

a

b

c

d

C

G Aa / D cC /

G Bb / D dD /

dt

dX

~3

3

dp

dE

)()(

)(

)(

)(~

/

/

/

/3

3

3

3

cdabaxG

xG

xG

xG

dpEd

dpEd

A LLbBb

bBb

aAa

aAa

UnPol. Case abcd

cC

abcd

bBbaAa zDdt

dxGxG )()()( ///

measurement

Structure Function pQCD Fragmentation Function

Asymmetry


Processes for Probes.

Gluon Compton

Charmonium

Open Heavy QuarkLight Flavor

　High-Pt prompt

e+e-, +-

e+e-, +- ,e,e, ,,Jet(Charged Hadrons, pi0)

Ah

Bh

q

q

l

lW boson (Z,Drell-Yan) High-Pt , e,

e+e-, +-

signature

Processes

W

Many processes on P-P collision can be used.


Accelerator and

Detectors


Polarized Proton Collider : RHIC

AGS

LINACBOOSTER

Pol. Proton Source500 A, 300 s

1232max scm102 L

Spin Rotators

Partial Siberian Snake

Siberian Snakes

200 MeV Polarimeter AGS Internal PolarimeterRf Dipoles

RHIC pC Polarimeters

Absolute Polarimeter (H jet)

2 1011 Pol. Protons / Bunch = 20 mm mrad

PHENIX

PHOBOSBRAHMS & PP2PP

STAR

onPolarizati Beam%70GeV50050 s

•Accelerator (ZELENSKI)

•Polarimeter (BRAVAR and JINNOUCHI)

•DetectorLocal Polarimeter Test set up


PHENIX collaboration

12 Countries 57 Institutions 460 Participants


PHENIXPioneering High Energy Nuclear Interaction eXperiment

PHENIX Detector1 Central Arm

e, g, Charged Hadrons detection |h|<0.35, Df=p

2, Muon Arm m detection 1.2<|h|<2.4, 2p in f

3, Forward detectors Luminosity Monitoring Local polarimetery

Good particle identification

High Rate and High Detector granularity.

Limited geometrical coverage


Coverage of Detector

0 1 2 3 4 5 Rapidity

STARFPD

PHENIX/STAR0o CAL

PHENIXBBC

PHE

NIX

MU

ON

PH

EN

IX C

EN

TR

AL

STA

R T

PC

pp2pp

XF 0.2 0.4 0.6 0.8PT


RHIC Run Summary at PHENIX

RUN Species EnergyLuminosi

tyPolarization

RUN 12000

Au + Au 130 GeV 1.0/mb 　

RUN 22001-2002

Au + Au 200 GeV 24/mb 　

P + P 200 GeV 150/nb Transverse

RUN 32002-2003

Au + Au 200 GeV 2.7/nb 　

P + P200 GeV 17/nb Transverse

200 GeV 350/nbLongitudina

l

Recorded on tape at PHENIX


pp-run-03 PHENIX integrated luminosity

352 nb-1 from 6.6x109 BBCLL1 triggers

0.00

100.00

200.00

300.00

400.00

500.00

600.00

700.00

800.00

900.00

1000.00

Date in proton run

Inte

grat

ed L

umin

osity

[nb

-1]

Integ. BBCLL1 Integ. ZDC

ZDC

BBC

STARrotators

pp2pp

Begin of Physics

2 IRsExtension: 180nb-1/wk, Pola-rization between 0.25 and 0.3.

Extended periods with pola-rization above 0.35 earlier inthe run.

Goal: 500nb-1/week at P=0.4

Commissioning: 5+3 weeks


Result from

RUN2 and RUN3


Central Arm Detector

)(GeV/ %0.1%7.0/ cppp

Tracking Detectors

2m ~ 4m from vertex

GeV)(

%2.8%9.1/

EEE

01.001.0~

Particle Identification

E.M. Calorimeter

High granularity


Leading hadrons as jet tags

ˆ

Hard Scattering Process

2P2 2x P

j 2f x

i 1f x1P

1 1x P

zhqD

s

1ps

2ps

gggg

G

G

G

G

gqgq

G

G

q

q

qqqq

q

q

q

q

qg+gq

qq

gg

0

Fraction

's produced

Pt [GeV/c]


p reconstruction at RUN3

2-3 GeV/c Bckgr=17%

3-4 GeV/c Bckgr=7%

4-5 GeV/c Bckgr=5%

1-2 GeV/cBckgr=45%

Results obtained for four pt bins from 1 to 5 GeV/c

Pi0 peak width varies from 12 to 9.5 MeV/c2 from lowest to highest pt bins

Background contribution under pi0 peak for 25 MeV/c2 mass cut varies from 45% to 5% from lowest to highest pt bins

0

A. Bazilevsky will talk.


Gluon Polarization measurement by leading hadrons

Estimate with 30pb-1, 70% Pol. Simulation

for different charges for different G

h+

h-

A

B

C

0

h+

AL

L

AL

L


Physics of J/• Better understanding of Quantum Chromo-

dynamics (QCD) charmonium production includes perturbative QCD aspects non-perturbative QCD aspects

• (Un-polarized) p+p data are important as reference for heavy ion collision

In wide energy rangeCross sectionsPolarizationRelative yields (/ etc)

Resolve production mechanism


Muon Arms

Geometry Acceptance North : 1.2 <η< 2.4 South: -2.2<η<-1.2 Muon range cut off ~ 2GeV/c

m/prejection ~10^3

Muon Tracker (MuTr) Measurement of momentum

Muon Identifier (MuID) Muon identification Trigger Counter

North Muon Arm:2002~

South Muon Arm

2001~

North Muon Arm became operation in 2003 Run

Beam

μ


J/ Peaks at RUN2

• Clear J/ peaks with small background in both e+e- and +- pairs

NJ/=46 NJ/=65


J/ (s dependence)sm

xgxgx

dxs

c

J

/2

)/()()(1

/

• Energy dependence of J/ is sensitive to gluon distribution function and its scale Q

• Our new result and lower-energy results are consistent with typical gluon distribution functions with a reasonable choice of Q confirms the gluon fusion picture of J/ production in hadron-hadron collisions in a wide energy range


J/ (absolute value)

• Absolute normalization for J/ is sensitive to production model – Color-evaporation model (CEM)

can explain J/ using J/ (fraction of J/ to all produced cc pairs) ~ 0.06 determined by photo-production data

– Color-singlet model (CSM)

Color singlet production underestimate J/ by a large (~10) factor– Color-octet model (COM)

Consistent using the color octet matrix element <OJ/8(1S0)>+7/Mc

2< OJ/

8(3P0)> = 0.02 GeV3 from photo-production data, but has large uncertainties from

• Extraction of color-octet matrix element• Charm quark mass• Factorization and renormalization scales


J/ψ　 at RUN3

Invariant Mass (GeV)0 31 2 4 5 6

First Detection J/ψ with North Muon Arm

Data Sample: Dimuon TriggerIntegrated Luminosity: 143 nb (~50% of run3pp)Dimuon sample : 3MJ/ψ: ~ 227 J/ψ’s

Expected number of J/ψ: 600 (North and South) Almost 10 times Statistics -> Pt, and J/ψ polarization?

-1


XF

Physics of Forward DetectorsFNAL E704 and Qiu-Sterman model

Tra

nsve

rse

Sin

gle

Spi

n A

sym

met

ryA

N

FNAL E704 measured large transverse single spin asymmetry AN

Instead Zero expectation from lowest order pQCD calculation

Possible origins

Initial state interaction

Final state fragmentation

Higher twist effect

Can we use as “Polarimeter”?

Let’s measure at RHIC!


Neutron Asymmetry at RUN2

RL

RLNA

onPolarizati Beam

1

Transverse single spin Asymmetry


ZDC (Zero Degree Calorimeter) at PHENIX RUN3

beam beam

～ 1800cm

10cm

±2mrad

beam beam

-EM and Hadron　 Calorimeter -> neutron, •Sweep out all charged particles -> only neutron and •Tungsten, Scintillation fiber, 2 layer of tungsten•X-Y from fiber, energy deposit from tungsten　　　　•5.1λT 149X0 (3 ZDC)

DX magnet

5||3

ZDC ZDC

DX magnet


Measure change of Polarization VectorR

aw A

sy.

/ B

eam

Pol

.

f-p/2 0 p/2-p/2 0 p/2-p/2 0 p/2

Transeverse(Vert.) Transeverse(Horiz,) Longitudinal

Evaluate longitudinal component of beam by measuring transverse component of polarization.

p

pT

pL

2

1cos

pT

p

pL

p

<pL/p> Blue = 0.993

<pL/p> Yellow = 0.974

0.005 0.0000.014 0.0090.013 0.0010.032 0.009


PHENIX BBC

• 2 identical parts (BBC-north and -south)

• Quartz Cherenkov counter• 64 segments each.

NorthSouth

144.35 cm

⊿φ = 2π

9.3||0.3

29

Inclusive Charged Asymmetry in forward region (3<||<4)

• No finite AN was found with looking at charged particle.

• But Large AN was found in neutron.

• How about charged particle with neutron tag?

Neutron Tag

Forward Charged

Backward Charged

210)22.050.050.4( 210)10.055.028.2(

Forward AN =

Backward AN =PHENIX preliminary


What’ next?


Prompt photon production• Gluon Compton Dominates

– At LOLO no fragmentation function– Small contamination from annihilation

•

2i i 2

i u,d,s

2i i 2

i u,d,s

LL1

1LL

e f (xg(

)

e f (A

x )a (gq

x )

g(x )q )

A1


–clear interpretation• gluon Compton

process dominant

statistics with full design luminosity and polarization

prompt photon

GS95

x

G x

Gluon polarization measurement by Prompt photon


Physics from Open heavy flavors

Provides more independent DG measurements in PHENIXHelps control experimental and theoretical systematic errorsDifferent channels cover different kinematic regions

bbeX

direct

cceX

H. Sato

gg QQA BLL LL

A B

G(x ) G(x ) ˆA aG(x ) G(x )

Decay channels: e+e-, +-, e, e, , eD, D

X


ALL in PHENIX using -e coincidences

320pb-1 data will provide us a lot of e- coincidences event in PHENIX acceptance

230K from charm and 142K from bottom are expected.

At high Pt region, bottom begins to dominate

W. Xie & H. Sato

simulation

simulation

70% polarization

70% polarization


Physics from W production

Au x M d x M d x M u x M

u x M d x M d x M u x MLW a W b W a W b W

a W b W a W b W

( , ) ( , ) ( , ) ( , )

( , ) ( , ) ( , ) ( , )

2 2 2 2

2 2 2 2

• W Asymmetry

V-A + helicity conservation

),(

),(2

2

Wa

WaWL Mxu

MxuA

),(

),(2

2

Wa

WaWL Mxd

MxdA

when ba xx

ba xx when

ud

• W production1) Parity violation Good spin analyzer2) Weak charge Flavor decompositionu

d W


Flavor decomposition

W

Z

W dominates high Pt m (>20 GeV/c)pb 1-800Ldt GeV, 500 s


In RUN3 PHENIX took longitudinally polarized proton-proton collision data with integrated luminosity 350/nb and average beam polarization 0.3. We measuredALL of inclusive 0

AN from forward detectors

PHENIX is well suited to the study of spin physics with a wide variety of probes.G with prompt , heavy flavor via lepton tagLeading particle from jet Anti-quark helicity distribution via W decay

Summary

Documents

Spin Physics at RHIC PHENIX 1.Physics Motivation 2.Accelerator and Detector 3.Result from Run2/Run3 4.What we can do? Atsushi Taketani RIKEN RIKEN Brookhaven