Spin-05 Dubna, Sep 28, 20051Dave Kawall (RIKEN-BNL and UMass) Title High Energy Spin Physics with the PHENIX detector At RHIC Dave Kawall, RIKEN-BNL and UMass, for PHENIX Collaboration

Spin-05 Dubna, Sep 28, 20052Dave Kawall (RIKEN-BNL and UMass) 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 A LL, Direct Photons, Charged Pions, Muons, Jets, Lamdbas …. Single Spin Asymmetries Summary

Spin-05 Dubna, Sep 28, 20053Dave Kawall (RIKEN-BNL and UMass) 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-p T 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

Spin-05 Dubna, Sep 28, 20054Dave Kawall (RIKEN-BNL and UMass) Hard Scattering Process a b c X RHIC Spin : Colliding beams of polarized partons Collide beams of polarized protons, 50+% polarization, sqrt(s)=200 GeV At high p T, sqrt(s), can factorize as beams of polarized partons a,b Helicity conservation in cross-section  (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

Spin-05 Dubna, Sep 28, 20055Dave Kawall (RIKEN-BNL and UMass) RHIC Spin : Colliding beams of polarized partons g+q->g+q Need to measure helicity dependent yields, N, Polarization, P, and Relative Luminosity, R

Spin-05 Dubna, Sep 28, 20056Dave Kawall (RIKEN-BNL and UMass) RHIC Spin : Colliding beams of polarized partons Interpretation of results relies on pQCD high p T and sqrt(s) help to reduce dependence on unphysical scales   M. Stratmann, W. Vogelsang)

Spin-05 Dubna, Sep 28, 20057Dave Kawall (RIKEN-BNL and UMass) 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

Spin-05 Dubna, Sep 28, 20058Dave Kawall (RIKEN-BNL and UMass) RHIC : The World’s only polarized proton collider Luminosity ~ 1x10 31 cm -2 sec -1 at Sqrt(s) = 200 GeV, P ~ 50% L ~ 2x10 32 cm -2 s -1, P ~ 70% in the future installed and commissioned during in 2004 run installed in 2005 and to be commissioned to be commissioned

Spin-05 Dubna, Sep 28, 20059Dave Kawall (RIKEN-BNL and UMass) Rb cell SCS solenoid Probe laser Cryopumps RHIC Optically Pumped Polarized Ion Source (OPPIS) Pump laser 28 GHz ECR Proton Source Na jet ionizer cell Polarized proton blowtorch : 80+ % polarization, ~1 mA H -, 200 microsecond pulses at 7.5 Hz -> 4x10 11 protons at 200 MeV after RFQ and Linac

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) Proton Beam Polarimetry : pC CNI Polarimeter CNI : analyzing power, A N, from interference of hadronic non-spin flip and EM spin flip amplitudes In p-Carbon, A N ~ 1-2% Need 10 7 events - but cross section large - just takes a few minutes A N absolute calibration from elastic pp scattering from polarized H gas jet target P B measured several times per store

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) Absolute polarimetry with Polarized Hydrogen Gas Jet Target Polarized hydrogen jet target for calibration of pC polarimeters Thickness : ~ 1.3 x atoms/cm 2 Polarization : 93% +1/-2% (uncertainty from H 2 fraction ) Located at IR 12 Event rates of a few Hz

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) 13 Countries, 62 Institutions, 550 People

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

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) PHENIX Polarized Proton Runs RunDatePolarizationRecorded Luminosity LP 4 Fig. of Merit Comments 1,22001, % Transverse 0.15 pb TB First polarized proton run ! (4 wks) 27% Longitudinal 0.35 pb TB 1.5 nb -1 Spin rotators commissioned, pC CNI polarimeters used (4 days) 40% Longitudinal 0.12 pb nb -1 AGS warm snake com., H jet abs. polarimeter (9 wks) 49%, 44% Long & Tran 3.8 pb TB 205 nb -1 Largest dataset by far ! AGS cold snake com., Few days at 410 GeV

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

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

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

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

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) PHENIX Local Polarimeter Stable spin direction vertical - spin rotators enable longitudinal collisions PHENIX discovered analyzing power in neutron production at low p T and high x F in pp collisions at Sqrt(s)=200 GeV Neutrons identified in ZDC + Shower Max Detector ~18 m 10cm (± 2mrad ) Blue beamYellow beam BlueYellow BlueYellow ZDC Spin Rotators Off Spin Rotators On

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) PHENIX Specialty : A LL of   in Central Arms A LL of   has contributions from  gx  g,  gx  q, and  qx  q Fractional contributions to   production (  g x  g) and (  g x  q) dominate below p T of ~ 7GeV/c At low p T, A LL of   depends on (  g) 2

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) PHENIX Specialty : A LL of   in Central Arms Identify   from  invariant mass peak,  extract A LL (  0 + BG1) and A LL (BG2) Fit  0 peak and get combinatorial background fraction Subtract A LL (BG2) from A LL (  0 + BG1) to get A LL (  0 )

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) Bunch shuffling A LL 2-3 GeV/c All 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  (A LL ) (Y.Goto) 2-3 GeV/c 3-4 GeV/c4-5 GeV/c 1-2 GeV/c Check for systematic effects by randomly assigning bunch helicity Expect A LL of shuffled bunches to be zero, width consistent with errors

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) PHENIX PRELIMINARY PHENIX Specialty : A LL of   in Central Arms confidence level PHENIX Data Comparison with Theory ->15% GRSV-std : best fit to pDIS results GRSV-max :  G(x)=G(x) at Q 2 0 =0.4 GeV 2

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) PHENIX Specialty : A LL of   in Central Arms Run 3 and Run 4 data distinguished between GRSV-max and GRSV-std Run 5 data should be able to distinguish GRSV-std from A LL = 0 4 pb -1, 50% pol.

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) Other Measurements : Cross-section and A N of Charged Hadrons Mid-rapidity neutral pion and charged hadron single transverse spin asym. A N consistent with zero Cross section consistent with pQCD 0.15 pb -1, Pol ~15 +/- 5%

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) Upcoming Measurements : A LL of Jets, J/  A LL 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 A LL of J/  e +/-, …. Spin transfer with  using many channels provides cross checks to reduce uncertainties, can extend x region we probe  g

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) Upcoming Results from 2005 Run 5 : A LL of Charged Pions A LL of charged pions from 5-15 GeV/c Charged pions identified by RICH and EMCal hadronic shower Sensitive to sign of (M. Stratmann)

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) Upcoming Measurements : A LL of Direct Photons direct   production dominated by gluon-Compton process : q+g -> q+   theoretically clean extraction of  g, sensitive to sign of  g small cross-section (~1 nb at p T =5 GeV) -> need high luminosity & polarization

Spin-05 Dubna, Sep 28, Dave Kawall (RIKEN-BNL and UMass) Summary Spin program well underway : have first measurements of A LL of neutral pions, and A N of neutral pions and charged hadrons Cross-sections consistent with NLO pQCD Expect to be able to extract polarized gluon dist. func. Upcoming results : A LL 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