Spin-05 Dubna, Sep 28, 20051Dave Kawall (RIKEN-BNL and UMass) Title High Energy Spin Physics with...

Spin-05 Dubna, Sep 28, 2005 1Dave Kawall (RIKEN-BNL and UMass)

Title

High Energy Spin Physics with the PHENIX detectorAt RHICDave Kawall, RIKEN-BNL and UMass, for PHENIX

Collaboration


Outline

• Physics motivation• Introduction to RHIC

• Polarized Source• pC Polarimeters• Hydrogen Gas Jet Target

• Introduction to PHENIX• PHENIX detectors• Local Polarimeters• Run History• Relative Luminosity

• Physics Analyses and Results• Neutral Pion ALL, Direct Photons, Charged Pions, Muons, Jets, Lamdbas ….• Single Spin Asymmetries

• Summary


Motivation for the RHIC Spin Program

• Proton spin sum rule :

• Polarized DIS experiments EMC, SMC, SLAC (E80,E131, E142-E155x), HERMES, COMPASS, JLAB - suggest

• Gluon contribution may be large, currently not well constrained

• accessible in pDIS from NLO pQCD analysis of scaling violations, and from high-pT hadron pair production in photon-gluon fusion, open charm production

• Photons don’t couple to gluons - but polarized hadron collisions can involve at leading order - a new approach

• RHIC Spin can run with transverse polarization : investigate transversity/ orbital angular momentum/quark-gluon correlations in proton

• Parity violation in W production : allows flavor separation

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1

2=

1

2Σ(Δq + Δq ) + ΔG + L

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Σ(Δq + Δq ) ≈ 0.25

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ΔG

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ΔG

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ΔG

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Δu,Δu ,Δd,Δd


Hard Scattering Process

2P22xP

1P

11xP

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Δfa (xa )

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Δfb (xb )

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Δ ˆ σ ab →cX

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Dcπ (zc )

a

b

c

X

RHIC Spin : Colliding beams of polarized partons

• Collide beams of polarized protons, 50+% polarization, sqrt(s)=200 GeV• At high pT, sqrt(s), can factorize as beams of polarized partons a,b

• Helicity conservation in cross-section Δ(ab-cX) can imply large analyzing power for some processes• We acquire sensitivity to polarized parton distributions, including gluon• Different processes -> different combinations of a,b,cross-section --> can cross-check our results and interpretation

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ALL ≈Δa

a⊗

Δb

b⊗Δ ˆ σ (

r a +

r b → c + X)



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ALL =1

P 2

N++ − N+−R

N++ + N+−R

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R =L++

L+−

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ALL =ΔG(x1)

G(x1)

Δq(x2)

q(x2)ˆ a LL

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≈ΔG(x1)

G(x1)A1

P (x2) ˆ a LL

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≈ΔG(x1)

G(x1)× 0.3× 0.6

g+q->g+q

• Need to measure helicity dependent yields, N, Polarization, P, and Relative Luminosity, R



• Interpretation of results relies on pQCD

• high pT and sqrt(s) help to reduce

dependence on unphysical scales M. Stratmann, W. Vogelsang)


PHENIX (and STAR) data well described by pQCD

• cross-section at mid-rapidity well described by NLO pQCD

• cross-section at mid-rapidity well described by NLO pQCD


RHIC : The World’s only polarized proton collider

• Luminosity ~ 1x1031 cm-2sec-1 at Sqrt(s) = 200 GeV, P ~ 50% • L ~ 2x1032 cm-2s-1, P ~ 70% in the future

BRAHMS & PP2PP

STAR

PHENIX

AGS

LINAC BOOSTERPol. H- Source

Spin Rotators(longitudinal polarization)

Solenoid Partial Siberian Snake

Siberian Snakes

200 MeV Polarimeter AGS Internal Polarimeter

Rf Dipole

RHIC pC PolarimetersAbsolute Polarimeter (H jet)

AGS pC PolarimetersStrong AGS Snake

Helical Partial Siberian Snake

PHOBOS

Spin Rotators(longitudinal polarization)

Spin flipper

Siberian Snakes

installed and commissioned during in 2004 runinstalled in 2005 and to be commissionedto be commissioned

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s

€

≈

€

≈

€ €

≈

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≈


Rb cellRb cell

SCS solenoidSCS solenoid

Probelaser

CryopumpsCryopumps

RHIC Optically Pumped Polarized Ion Source (OPPIS)

Pumplaser

28 GHz ECR Proton Source Na jet ionizer cell

• Polarized proton blowtorch : 80+ % polarization, ~1 mA H-, 200 microsecond pulses at 7.5 Hz -> 4x1011 protons at 200 MeV after RFQ and Linac


Proton Beam Polarimetry : pC CNI Polarimeter

• CNI : analyzing power, AN, from interference of hadronic non-spin flip and EM spin flip amplitudes• In p-Carbon, AN ~ 1-2%• Need 107 events - but cross section large - just takes a few minutes• AN absolute calibration from elastic pp scattering from polarized H gas jet target

•

• PB measured several times per store

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PB = −1

AN

NLeft − NRight

NLeft + NRight


Absolute polarimetry with Polarized Hydrogen Gas Jet Target Absolute polarimetry with Polarized Hydrogen Gas Jet Target

• Polarized hydrogen jet target

for calibration of pC polarimeters

•Thickness : ~ 1.3 x 1012 atoms/cm2

• Polarization : 93% +1/-2%

(uncertainty from H2 fraction )

• Located at IR 12

• Event rates of a few Hz


• University of São Paulo, São Paulo, Brazil• Academia Sinica, Taipei 11529, China• China Institute of Atomic Energy (CIAE), Beijing, P. R. China• Peking University, Beijing, P. R. China• Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 12116

Prague, Czech Republic• Czech Technical University, Faculty of Nuclear Sciences and Physical

Engineering, Brehova 7, 11519 Prague, Czech Republic• Institute of Physics, Academy of Sciences of the Czech Republic, Na

Slovance 2, 182 21 Prague, Czech Republic• Laboratoire de Physique Corpusculaire (LPC), Universite de Clermont-

Ferrand, 63 170 Aubiere, Clermont-Ferrand, France• Dapnia, CEA Saclay, Bat. 703, F-91191 Gif-sur-Yvette, France• IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406 Orsay, France• Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de

Saclay, F-91128 Palaiseau, France• SUBATECH, Ecòle des Mines at Nantes, F-44307 Nantes France• University of Muenster, Muenster, Germany• KFKI Research Institute for Particle and Nuclear Physics at the Hungarian

Academy of Sciences (MTA KFKI RMKI), Budapest, Hungary• Debrecen University, Debrecen, Hungary• Eövös Loránd University (ELTE), Budapest, Hungary• Banaras Hindu University, Banaras, India• Bhabha Atomic Research Centre (BARC), Bombay, India• Weizmann Institute, Rehovot, 76100, Israel• Center for Nuclear Study (CNS-Tokyo), University of Tokyo, Tanashi, Tokyo

188, Japan• Hiroshima University, Higashi-Hiroshima 739, Japan• KEK - High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba,

Ibaraki 305-0801, Japan• Kyoto University, Kyoto, Japan• Nagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki, Japan• RIKEN, The Institute of Physical and Chemical Research, Wako, Saitama 351-

0198, Japan• RIKEN – BNL Research Center, Japan, located at BNL• Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima,

Tokyo 171-8501, Japan• Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan• University of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi Ibaraki-ken 305-8577,

Japan• Waseda University, Tokyo, Japan• Cyclotron Application Laboratory, KAERI, Seoul, South Korea• Kangnung National University, Kangnung 210-702, South Korea• Korea University, Seoul, 136-701, Korea• Myong Ji University, Yongin City 449-728, Korea• System Electronics Laboratory, Seoul National University, Seoul, South

Korea• Yonsei University, Seoul 120-749, Korea• IHEP (Protvino), State Research Center of Russian Federation "Institute for

High Energy Physics", Protvino 142281, Russia• Joint Institute for Nuclear Research (JINR-Dubna), Dubna, Russia• Kurchatov Institute, Moscow, Russia• PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region,

188300, Russia• Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State

University, Vorob'evy Gory, Moscow 119992, Russia• Saint-Petersburg State Polytechnical Univiversity, Politechnicheskayastr, 29,

St. Petersburg, 195251, Russia

Map No. 3933 Rev. 2 UNITED NATIONSAugust 1999

Department of Public InformationCartographic Section

• Lund University, Lund, Sweden• Abilene Christian University, Abilene, Texas, USA• Brookhaven National Laboratory (BNL), Upton, NY 11973, USA• University of California - Riverside (UCR), Riverside, CA 92521, USA• University of Colorado, Boulder, CO, USA• Columbia University, Nevis Laboratories, Irvington, NY 10533, USA• Florida Institute of Technology, Melbourne, FL 32901, USA• Florida State University (FSU), Tallahassee, FL 32306, USA• Georgia State University (GSU), Atlanta, GA, 30303, USA• University of Illinois Urbana-Champaign, Urbana-Champaign, IL, USA• Iowa State University (ISU) and Ames Laboratory, Ames, IA 50011, USA• Los Alamos National Laboratory (LANL), Los Alamos, NM 87545, USA• Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA• University of New Mexico, Albuquerque, New Mexico, USA• New Mexico State University, Las Cruces, New Mexico, USA• Department of Chemistry, State University of New York at Stony Brook (USB),

Stony Brook, NY 11794, USA• Department of Physics and Astronomy, State University of New York at Stony

Brook (USB), Stony Brook, NY 11794, USA• Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA• University of Tennessee (UT), Knoxville, TN 37996, USA• Vanderbilt University, Nashville, TN 37235, USA

13 Countries, 62 Institutions, 550 People


PHENIX Detector

• High resolution, limited acceptance

• DAQ can record 5 K events/sec

• Triggers for rare events • Central tracking : Pad

chamber (PC), drift chamber (DC), time expansion chamber (TEC)

• Central Arm Calorimeters : PbSc and PbGl, finely segmented

• Forward tracking: Muon tracker

• Particle ID : Muon ID, RICH, TOF, TEC

• Global Detectors: Beam-Beam Counter (BBC) , Zero-Degree-Calorimeter (ZDC)


PHENIX Polarized Proton Runs

Run Date Polarization Recorded Luminosity

LP4 Fig. of Merit

Comments

1,2 2001,2002

15%Transverse

0.15 pb-1

20 TB

First polarized proton run !

3 2003(4 wks)

27%Longitudinal

0.35 pb-1

35 TB1.5 nb-1 Spin rotators

commissioned, pC CNIpolarimeters used

4 2004(4 days)

40%Longitudinal

0.12 pb-1 3.3 nb-1 AGS warm snake com.,H jet abs. polarimeter

5 2005(9 wks)

49%, 44%Long & Tran

3.8 pb-1

262 TB205 nb-1

Largest dataset by far !

AGS cold snake com.,Few days at 410 GeV


• Same bunches from each ring collide with each other at 78 kHz

• Spin pattern alternates with every bunch crossing• Collecting ++,+-,--,-+ simultaneously reduces systematics• 56 crossings in 2001-2004, up to 106 colliding pairs in

2005

How the Bunches Collide in RHIC

• Spins can be flipped and colliding pairs can be altered

• bunch-by-bunch differences in luminosity and vertex distribution are investigated carefully


PHENIX Local Polarimeter

• Stable spin direction vertical - spin rotators enable longitudinal collisions

• PHENIX discovered analyzing power in neutron production at low pT

and high xF in pp collisions at Sqrt(s)=200 GeV

• Neutrons identified in ZDC + Shower Max Detector~18 m

10cm (±2mrad)Blue beam Yellow beam

Blue Yellow

Blue Yellow

ZDC

ZDC

Spin Rotators Off

Spin Rotators On


PHENIX Specialty : ALL of in Central Arms

• ALL of has contributions from ΔgxΔg, ΔgxΔq, and ΔqxΔq

Fractional contributions to production

• (Δg x Δg) and (Δg x Δq) dominate below pT of ~ 7GeV/c• At low pT, ALL of depends on (Δg)2



• Identify from invariant mass peak, extract ALL (0 + BG1) and ALL(BG2)

• Fit 0 peak and get combinatorial background fraction

• Subtract ALL(BG2) from ALL(0 + BG1) to get ALL(0)


Bunch shuffling

ALL

2-3 GeV/c

• All <2/NDF> are ~1• Consistent with stat. distribution of 2/NDF

2/NDF

3-4 GeV/c 4-5 GeV/c

1-2 GeV/c

• Widths are consistent with stat.

errors (ALL) (Y.Goto)

2-3 GeV/c

3-4 GeV/c 4-5 GeV/c

1-2 GeV/c

• Check for systematic effects by randomly assigning bunch helicity

• Expect ALL of shuffled bunches to be zero, width consistent with errors


PHENIX PRELIMINARY


confidence level

PHENIX Data Comparison with Theory

->15% ->15%

• GRSV-std : best fit to pDIS results

• GRSV-max : ΔG(x)=G(x) at Q20=0.4 GeV2

€

ΔG(x,Q2 =1GeV 2)dx ≈ 0.70

1

∫



• Run 3 and Run 4 data distinguished between GRSV-max and GRSV-std

• Run 5 data should be able to distinguish GRSV-std from ALL = 0

4 pb-1, 50% pol.


Other Measurements : Cross-section and AN of Charged Hadrons

• Mid-rapidity neutral pion and charged hadron single transverse spin asym.• AN consistent with zero• Cross section consistent with pQCD• 0.15 pb-1, Pol ~15 +/- 5%


Upcoming Measurements : ALL of Jets, J/

• ALL of jet-like cluster• trigger on photon, sum energy in central arm - get most of a jet• Potential for high statistics, relatively clean theoretical interpretation

• ALL of J/ e+/-, ….• Spin transfer with • using many channels provides cross checks to reduce uncertainties, can extend x region we probe Δg


Upcoming Results from 2005 Run 5 : ALL of Charged Pions

• ALL of charged pions from 5-15 GeV/c • Charged pions identified by RICH and EMCal hadronic shower• Sensitive to sign of (M. Stratmann)

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ΔG


Upcoming Measurements : ALL of Direct Photons

• direct production dominated by gluon-Compton process : q+g -> q+• theoretically clean extraction of Δg, sensitive to sign of Δg• small cross-section (~1 nb at pT=5 GeV) -> need high luminosity & polarization


Summary

• Spin program well underway : have first measurements of ALL of

neutral pions, and AN of neutral pions and charged hadrons

• Cross-sections consistent with NLO pQCD

• Expect to be able to extract polarized gluon dist. func.

• Upcoming results : ALL of neutral pions, direct photons,

etas, J/Psi, jets, charged hadrons, spin transfer in

• Collider improvements : Cold snake in AGS -> polarization and

luminosity should increase

Spin-05 Dubna, Sep 28, 20051Dave Kawall (RIKEN-BNL and UMass) Title High Energy Spin Physics with...

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