Measurements of Hadron Production in d+Au Collisions with the PHENIX Experiment at RHIC

Measurements of Hadron Production in d+Au Collisionswith the PHENIX Experiment at RHIC

12009 Winter Workshop on Nuclear Dynamics2009-02-06

Young Jin KimUniversity of Illinois at Urbana-Champaign

Contents


1. Introduction

2. Observables in d+Au Nuclear Modification Factor (RdA, Rcp) Angular Correlation (IdA)

3. PHENIX Detector MPC

4. 2008 RHIC Run with PHENIX

5. Summary

Introduction


F2D

/F2A

1.

1.

0.

0.

0.

0.

1.

1.

Structure functions are altered in nuclei x > 0.7: ratio increases, crosses 1.0(Fermi momentum smearing)0.2< x < 0.7: suppression(EMC Effect)0.05 < x < 0.2: small enhancement(anti-shadowing)x < 0.05: shadowingSaturation?

high x low x

Saturation or Color Glass Condensate (CGC)• At low-x there are so many gluons that 2 1 diagrams become important• Nuclear amplification: xAG(xA)=A1/3xpG(xp),

i.e. gluon density is ~6x higher in Gold than the nucleon

Nuclear Modification Factor (RdA) at RHIC


BRAHMS Collaboration, PRL 93, 242303 (2004)

PHENIX Collaboration, PRL 98, 172302 (2007)Central Arms: || < 0.35

STAR Collaboration,PRL 97, 152302 (2006)

Nuclear Modification Factor (Rcp) at RHIC


BRAHMS Collaboration,PRL 93, 242303 (2004)

PHENIX Collaboration, PRL 94, 082302 (2005)

PTH: Punch-through hadrons, HDM: Hadron decay methodBackward: -2.2 < < -1.2, Forward: 1.2 < < 2.4

Nuclear Modification Factor (Rcp) at RHIC


BRAHMS Collaboration, PRL 93, 242303 (2004)PHENIX Collaboration, PRL 94, 082302 (2005)

PTH: Punch-through hadronsHDM: Hadron decay methodBackward: -2.2 < < -1.2Forward: 1.2 < < 2.4

Observation of suppression in the forward direction. However, alternative explanations exist: Can correlation measurements distinguish between models?

Angular Correlation


D. Kharzeev, E. Levin, and L. McLerran, NPA 748, 627 (2005)

The evolution between the jets makes the correlations disappear.

STAR Collaboration, PRL 97, 152302 (2006)

π0: <η> = 4.0h±: |η| < 0.75, Pt > 0.5 GeV/c

IdA at PHENIX


PHENIX Collaboration, PRL 96, 222301 (2006)

|assoc| < 0.35

Measured two-particle distribution

Two-particle acceptance obtained by mixing trigger particles and associated particles from different events

PHENIX Detector


Deuteron Au

Central Arms:hadrons, photons, electrons |η| < 0.35 Δφ = π (2 arms x π/2)

Forward Rapidity Arms: muons 1.2 < |η| < 2.2 Δφ = 2π

Global Detectors:Beam-Beam Counter (BBC)Zero Degree Calorimeter (ZDC)Reaction Plane Detector (RxNP)

Moun Piston Calorimeter (MPC)


Electromagnetic calorimeter using PbWO4 crystal towersUse to detect neutral pions

South MPC: 196 towers, 3.1 < < 3.7North MPC: 220 towers, 3.1 < < 3.9 ~ 0.010.01(comparable to central arms)

PbWO4 Crystal and APD


Density 8.28 g/cm3

Size 2.2x2.2x18 cm3

Length 20 X0, 0.92

Weight 721.3 g

Moliere radius 2.0 cm

Radiation Length 0.89 cm

Interaction Length 22.4 cm

Light Yield ~10 p.e./MeV @ 20C

Temp. Coefficient -2%/C

Radiation Hardness 1000 Gy

Main Emission Lines 420-440, 500 nm

Refractive Index 2.16

PbWO4 crystal:For use in PHOS detector at ALICE/LHCBuilt by Kurchatov group

APD and PreAmp:From Hiroshima group

PreAmp

APD Holder

PbWO4 Crystal

Characteristics of PbWO4

APD

MPC 2006 - 2008


South North

2006 RHIC Run(200 GeV, 62 GeV polarized p+p):South MPC successfully installed

First Result: AN at 62 GeV

M. Chiu at Spin 2006

MPC has preformed nicelyFirst MPC result on neutral pion AN at 62 GeV

E.P.{2}BBC+MPC+RXN(SN)

E.P.{2}RXN(SN)

E.P.{2}RXN-IN(SN)

E.P.{2}RXN-OUT(SN)

E.P.{2}BBC+MPC(SN)

E.P.{2}MPC(SN)

E.P.{2}BBC(SN)

MPC 2006 - 2008


South North

2007 RHIC Run(200 GeV, Au+Au):North MPC successfully installed

Rea

ctio

n p

lan

e re

solu

tion

Centrality bin

MPC can help reaction plane reconstructionSeveral analyses are underway(e.g. di-hadron Ridge, Et distribution)

MPC 2006 - 2008


South North2008 RHIC Run(200 GeV, d+Au, polarized p+p):Upgraded Gain Monitoring System installed30 times more data taken than 2003 RHIC Run

200 GeV p+p

North South

Thin black: invariant massRed: background (by event mixing)Blue: signalThick black: Gaussian fit on signal

Neutral Pion Invariant Mass at MPC


200 GeV d+AuCentrality: 20-40%

Thin black: invariant massRed: background (by event mixing)Blue: signalThick black: Gaussian fit on signal

North MPCd moving out side

South MPCAu moving out side

Analyze MPC data of 200 GeV d+Au, p+p from 2008 RHIC RunCalibration and efficiency estimation are working in progressRdA, Rcp, IdA, MPC-Central arm correlation, MPC-MPC (back-to-back) correlation, etc.

PHENIX d+Au Analysis (working in progress)


0-20%/60-88%

North MPC (3.1 < < 3.9)d moving out side

Pt (GeV/c)

Projection statistical errors for 0+h angular correlation(0) = 3.1-3.9, |(h)| < 0.35Pt(0) = 1-2 GeV/c, Pt(h)=1-2 GeV/c

0-h

Projected statistical errors for Nuclear modification factor (Rcp)

Stay tuned, a lot of RHIC results at QM09 from PHENIX and STAR

Arb

itra

ry u

nit

Perspective on PHENIX IdA


South MPC

South Muon Arm

Central Arm

North Muon Arm

North MPC

Particle Detection 0 h+/- Identified

hadrons

h+/- 0

min

max

-3.7-3.1

-2.0-1.4

-0.35+0.35

1.42.0

3.13.9

PRL 96, 222301

PRL 96, 222301

Backward/Central

Forward/Central

Forward/BackwardRapidity scan is possibleForward/Backward correlation has largest ∆η

Summary


Search for saturation at low x is underway

Important input for initial state in HI-collisions!

RHIC results available for 2003 d+Au

•observed suppression in forward region•first exploratory correlation measurements

PHENIX and STAR have taken large d+Au data samples in 2008 with new forward detectors enabling correlation measurements with high statistics and over larger rapidity intervals

Documents

Measurements of Hadron Production in d+Au Collisions with the PHENIX Experiment at RHIC