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Spin Physics at RHIC PHENIX

Spin Physics at RHIC PHENIX. Atsushi Taketani RIKEN RIKEN Brookhaven Research Center. Physics Motivation Accelerator and Detector Result from Run2/Run3 What we can do?. Physics Motivation. Spin Structure of the Nucleon. What is the origin of the Nucleon Spin?

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Spin Physics at RHIC PHENIX

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

  2. Physics Motivation Atsushi Taketani RIKEN/RBRC

  3. Spin Structure of the Nucleon What 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 ~ ? q Polarized proton Collider Experiment Atsushi Taketani RIKEN/RBRC

  4. General Idea of Measurement C A a c X b B d UnPol. Case Asymmetry Structure Function pQCD Fragmentation Function measurement Atsushi Taketani RIKEN/RBRC

  5. Processes for Probes. signature Processes High-Pt prompt  Gluon Compton Charmonium e+e-, +- Open Heavy Quark Light Flavor e+e-, +-,e,e, ,, Jet(Charged Hadrons, pi0) High-Pt,e, e+e-, +- W boson (Z,Drell-Yan) W Many processes on P-P collision can be used. Atsushi Taketani RIKEN/RBRC

  6. Accelerator and Detectors Atsushi Taketani RIKEN/RBRC

  7. Polarized Proton Collider : RHIC • Accelerator (ZELENSKI) • Polarimeter (BRAVAR andJINNOUCHI) • Detector RHIC pC Polarimeters Local Polarimeter Test set up BRAHMS & PP2PP PHOBOS Absolute Polarimeter (H jet) PHENIX STAR Siberian Snakes Spin Rotators 2  1011 Pol. Protons / Bunch e = 20 p mm mrad Partial Siberian Snake LINAC BOOSTER Pol. Proton Source 500 mA, 300 ms AGS AGS Internal Polarimeter 200 MeV Polarimeter Rf Dipoles Atsushi Taketani RIKEN/RBRC

  8. PHENIX collaboration 12 Countries 57 Institutions 460 Participants Atsushi Taketani RIKEN/RBRC

  9. PHENIXPioneering High Energy Nuclear Interaction eXperiment PHENIX Detector 1 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 Atsushi Taketani RIKEN/RBRC

  10. Coverage of Detector PT XF 0.2 0.4 0.6 0.8 STAR TPC PHENIX CENTRAL PHENIX MUON STAR FPD pp2pp PHENIX BBC PHENIX/STAR 0o CAL 0 1 2 3 4 5 Rapidity Atsushi Taketani RIKEN/RBRC

  11. RHIC Run Summary at PHENIX Recorded on tape at PHENIX Atsushi Taketani RIKEN/RBRC

  12. ZDC BBC 2 IRs Extension: 180nb-1/wk, Pola- rization between 0.25 and 0.3. Extended periods with pola- rization above 0.35 earlier in the run. Goal: 500nb-1/week at P=0.4 Commissioning: 5+3 weeks STAR rotators pp2pp Begin of Physics Atsushi Taketani RIKEN/RBRC

  13. Result from RUN2 and RUN3 Atsushi Taketani RIKEN/RBRC

  14. Central Arm Detector Tracking Detectors 2m ~ 4m from vertex Particle Identification E.M. Calorimeter High granularity Atsushi Taketani RIKEN/RBRC

  15. Leading hadrons as jet tags Hard Scattering Process qg+gq qq gg Atsushi Taketani RIKEN/RBRC Pt [GeV/c]

  16. 0 preconstruction at RUN3 A. Bazilevsky will talk. 1-2 GeV/c Bckgr=45% 2-3 GeV/c Bckgr=17% 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 3-4 GeV/c Bckgr=7% 4-5 GeV/c Bckgr=5% Atsushi Taketani RIKEN/RBRC

  17. Gluon Polarization measurement by leading hadrons Estimate with 30pb-1, 70% Pol. Simulation ALL ALL h+ h+ A p0 B h- C for different charges for different DG Atsushi Taketani RIKEN/RBRC

  18. 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 Cross sections Polarization Relative yields (/ etc) In wide energy range Resolve production mechanism Atsushi Taketani RIKEN/RBRC

  19. Muon Arms North Muon Arm became operation in 2003 Run Muon Tracker (MuTr) Measurement of momentum Muon Identifier (MuID) Muon identification Trigger Counter μ Beam Geometry Acceptance North : 1.2 <η< 2.4 South: -2.2<η<-1.2 Muon range cut off ~ 2GeV/c m/prejection ~10^3 South Muon Arm 2001~ North Muon Arm: 2002~ Atsushi Taketani RIKEN/RBRC

  20. J/ Peaks at RUN2 • Clear J/ peaks with small background in both e+e- and +- pairs NJ/=46 NJ/=65 Atsushi Taketani RIKEN/RBRC

  21. J/ (s dependence) • 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 Atsushi Taketani RIKEN/RBRC

  22. 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/Mc2< 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 Atsushi Taketani RIKEN/RBRC

  23. Data Sample: Dimuon Trigger Integrated Luminosity: 143 nb (~50% of run3pp) Dimuon sample : 3M J/ψ: ~ 227 J/ψ’s Expected number of J/ψ: 600 (North and South) Almost 10 times Statistics -> s, Pt, and J/ψ polarization? 0 1 2 3 4 5 6 Invariant Mass (GeV) -1 J/ψat RUN3 First Detection J/ψ with North Muon Arm Atsushi Taketani RIKEN/RBRC

  24. FNAL E704 and Qiu-Sterman model AN Transverse Single Spin Asymmetry Physics of Forward Detectors 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! XF Atsushi Taketani RIKEN/RBRC

  25. Neutron Asymmetry at RUN2 Transverse single spin Asymmetry Atsushi Taketani RIKEN/RBRC

  26. ZDC (Zero Degree Calorimeter) at PHENIX RUN3 ZDC ZDC ～1800cm 10cm beam beam DX magnet DX magnet ±2mrad • -EM and HadronCalorimeter -> neutron, g • Sweep out all charged particles -> only neutron and g • Tungsten, Scintillation fiber, 2 layer of tungsten • X-Y from fiber, energy deposit from tungsten • 5.1λT 149X0 (3 ZDC) beam Atsushi Taketani RIKEN/RBRC beam

  27. Transeverse(Vert.) Transeverse(Horiz,) Longitudinal Raw Asy. / Beam Pol. -p/2 -p/2 -p/2 0 0 0 p/2 p/2 p/2 f p pT q pL Measure change of Polarization Vector Evaluate longitudinal component of beam by measuring transverse component of polarization. <pL/p> Blue= 0.993K K <pL/p> Yellow= 0.974K K 0.005 0.000 0.014 0.009 0.013 0.001 0.032 0.009 Atsushi Taketani RIKEN/RBRC

  28. South North ⊿φ = 2π 144.35 cm PHENIX BBC • 2 identical parts (BBC-north and -south) • Quartz Cherenkov counter • 64 segments each. Atsushi Taketani RIKEN/RBRC

  29. No finite AN was found with looking at charged particle. But Large AN was found in neutron. How about charged particle with neutron tag? Backward Charged Neutron Tag Forward Charged Forward AN = PHENIX preliminary Backward AN = Inclusive Charged Asymmetry in forward region (3<|h|<4)

  30. What’ next? Atsushi Taketani RIKEN/RBRC

  31. Prompt photon production • Gluon Compton Dominates • At LO no fragmentation function • Small contamination from annihilation A1 Atsushi Taketani RIKEN/RBRC

  32. GS95 prompt photon Gluon polarization measurement by Prompt photon • clear interpretation • gluon Compton process dominant statistics with full design luminosity and polarization Atsushi Taketani RIKEN/RBRC

  33. direct  bbeX cceX Physics from Open heavy flavors • Decay channels: • e+e-, m+m-, em, e, m, eD, mD X H. Sato • Provides more independent DG measurements in PHENIX • Helps control experimental and theoretical systematic errors • Different channels cover different kinematic regions Atsushi Taketani RIKEN/RBRC

  34. ALL in PHENIX using m-e coincidences • 320pb-1 data will provide us a lot of e-m coincidences event in PHENIX acceptance • 230K from charm and 142K from bottom are expected. • At high Pt region, bottom begins to dominate 70% polarization simulation 70% polarization simulation Atsushi Taketani RIKEN/RBRC W. Xie & H. Sato

  35. W production 1) Parity violation Good spin analyzer 2) Weak charge Flavor decomposition • W Asymmetry when V-A + helicity conservation when Physics from W production Atsushi Taketani RIKEN/RBRC

  36. W Z W dominates high Pt m (>20 GeV/c) Flavor decomposition Atsushi Taketani RIKEN/RBRC Note: W+ and W-- have a different acceptance In PHENIX.

  37. Summary • In RUN3 PHENIX took longitudinally polarized proton-proton collision data with integrated luminosity 350/nb and average beam polarization 0.3. We measured • ALL of inclusive p0 • AN from forward detectors • PHENIX is well suited to the study of spin physics with a wide variety of probes. • DG with prompt g, • heavy flavor via lepton tag • Leading particle from jet • Anti-quark helicity distribution via W decay Atsushi Taketani RIKEN/RBRC

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