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Measurement of the Gluon Polarization with the PHENIX Muon Arms

Measurement of the Gluon Polarization with the PHENIX Muon Arms. Hiroki Sato Kyoto University 10/20/00 SPIN2000, the 14th International Spin Physics Symposium, Osaka. Status of ΔG Measurement. proton spin. quark spin. gluon spin. 0.1～0.3. orbital angular moment.

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Measurement of the Gluon Polarization with the PHENIX Muon Arms

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  1. Measurement of the Gluon Polarization with the PHENIX Muon Arms Hiroki Sato Kyoto University 10/20/00 SPIN2000, the 14thInternational Spin Physics Symposium, Osaka

  2. Status of ΔG Measurement proton spin quark spin gluon spin 0.1～0.3 orbital angular moment 1/2 = (1/2) + G + L + LG Polarized Deep Inelastic Scattering ΔG SMC(1997) Q2=10GeV2 Altarelli. et.al (1997)Q2= E155(1999) Q2=5GeV2 Large uncertainty for indirect measurement Direct measurement with polarized p-p collisions （RHIC）

  3. simulation ALL G(x) ? Probes for ΔG Measurement Charmonium Production Di-leptons e+e-, +- • ALL is measured by the experiments. • Estimate how sensitive the obtained ALLis to G(x) by simulation Lepton decay channels Open Heavy Quark Production e+e-, +- ,e single e, eD, D Parton level asymmetry obtained by p-QCD calculation Experiment

  4. 1.5 2 ΔG（ｘ） 5 x T.Gehrmann and W.J.Stirling(1995) ALL Prediction aLL cos* M.Karliner and R.W.Robinett(1993) • One model of G(x, Q2) assuming a simple parameterized function • 3 sets of parameters ( GS-A, B. and C) • Leading order calculation • NLO calculation will be available soon

  5. ALL Experimental Errors PB1,2　Beam Polarization　～　0.7 (RHIC) 　　N++（N+－）Number of events +‐: Beam Helicity 　　L++（L+－）Luminosity • Statistical Error • Systematic Errors • PB１,2→ ALL/ALL ~ 20% • (L+－/L++) → ALL ~ 10ｰ4 • Nbg/Nsig ,ALLbg It’s necessary to know luminosity bunch by bunch

  6. RHIC/Spin Overview • 70% polarized proton beams in two independent rings • Two Siberian Snakes in each ring to keep polarization • CNI polarimeter and polarized jet target to measure polarization • 2000polarized proton commissioning in one ring • 2001 first physics runwith √s = 200 GeV, 32pb-1 luminosity • 2001√s = 200 GeV, 320pb-1 • 2002 ~√s = 500 GeV

  7. Lepton Measurement with PHENIX  (Muon Arms) • Tracking + MuID • 1.2 < || < 2.4 • p  2GeV/c e (Central Arms) • Tracking + RICH + EMCal • || < 0.35 • pT  0.2GeV/c

  8. South Arm North Arm collar PHENIX Muon Arms Acceptance 1.2 < || < 2.4 total absorber ~10λint Momentum cut ~ 2GeV/c Beam collar • Muon Tracker (MuTr) • Cathode readout chambers at three stations • x ~ 100m → Δp/p~3%@3~10GeV/c • Muon Identifier (MuID)　 • 　5 layers of Iarocci tubes (2-dimentional) sandwiched in steel • 　used as a trigger counter

  9. 320pb-1 p+p,s=200GeV ALLJ/ J/ （Color Singlet Model） pT()>2GeV/c Production Mechanism of J/ ? Yield per Bin(0.2GeV/c2) bottom /K G(x) M(GeV/c2) J/→ PYTHIA 5.7+GRV94-LO NJ/(pT>2GeV) ~120k → ALLJ/ (stat.) ~ 0.006 N/K/NJ/ ~ 0.15, ALL/K ~ 0.007→ ALLJ/(syst.) ~ 0.001 Experimentally it’s easier to measure, but it’s not straightforward to extract G(x) from ALL since production mechanism of J/ is still unknown

  10. 320pb-1 s=200GeV pTe,pT>1GeV/c total Yield per 1GeV/c2 _ cc→e /K→e _ bb→e Me(GeV/c2) Me(GeV/c2) e pairs • background of electrons (0Dalitz decay and  conversion) can be reduced using MVD →　studied by Ken Barish and Wei Xie • b/c separation is under studying → important because ALL is different • Mass selection • Use same sign pair Nbb→eμ~120k events Ncc→eμ~100k events N/K→eμ~60k events ALL(stat.)~ 0.006 ALL(syst.)~0.006 PYTHIA 5.7+GRV94-LO

  11. s=200GeV bbe (pTe,pT >1GeV/c) 0.031 ALL Stat. Error with 320pb-1 0.014 0.012 0.014 0.017 GS-A GS-B GS-C G(x) Sensitivity of e pairs • Sensitivity is enough to separate GS-A from other sets with 320pb-1

  12. bbe (pTe,pT >1GeV/c) log10 x1 Central Arm ｂ→e proton x1P x2 ｂ→ x2P Muon Arm log10 x2 Pz (GeV/c) e pairs x region Correlation is smeared by decay kinematics Regions of x1 and x2 are different because of different acceptance of electrons and muons

  13. G(x) Sensitivity of Single Electrons s=200GeV For detail, refer to the poster of Ken Barish Statistical error only With 320pb-1 statistical error only (with 32pb-1) preliminary log10x pT>2GeV/c 1<pT<2GeV/c log10x PYTHIA 5.7+GRV94-LO

  14. direct  bbeX cceX G(x) Sensitivity Summary Sensitive x:Q2 region Experimental uncertainties for ALL Together with theoretical predictions Our data covers large kinematical region including various processes *with color octet model **with 32pb-1 Experimental uncertainties are small compared to theoretical predictions.

  15. Z Y X MuID Commissioning with Au+Au Collisions • Limited Configuration • South Arm • 3 layers (out of 5) • 29 channels/layer • (out of 634) • Chambers are working well • Hit rate is consistent with simulation • Tracks are reconstructed

  16. MuTr Status and Plan • All chambers were installed in South Arm • Measured position resolution ~100μm → good enough to separate ψ’ from J/ψ • South Arm Roll in →　Dec. 2000 • North Arm →　2001 ~

  17. Polarized Proton Commissioning • Polarized protons were confirmed in one RHIC ring by measuring non-zero asymmetry with CNI polarimeter.. • Siberian snake worked as we expected. • Beam was accelerated up to p=29GeV/c withpolarization being kept. Preliminary For more detail, refer to Kazu Kurita’s poster (#3-7)

  18. Summary and Conclusions • We have estimated experimental uncertainties and theoretical predictions of ALL for charmonium and open heavy-flavor production measured at PHENIX. →　 ALL for leptonic decay channels of heavy-flavors will bring many inputs on gluon polarization in the proton. • Detectors and accelerator have been making significant progresses. → Ready for the first spin physics run (2001).

  19. J/ log10x2 bbeX ΔG（ｘ） cceX x log10x1 T.Gehrmann and W.J.Stirling(1995) Sensitive x region Electron and muon channels covers x range complementary. Direct photon cc->eX bb->eX J/

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