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Abhay Deshpande RIKEN BNL Research Center

APS-DNP 2003, Tucson AZ. Measurement of single transverse spin asymmetry A N in forward neutron production at PHENIX (Experimental confirmation of longitudinally polarized proton beams at PHENIX). Abhay Deshpande RIKEN BNL Research Center. RHIC Spin Physics Program. Transverse

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Abhay Deshpande RIKEN BNL Research Center

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  1. APS-DNP 2003, Tucson AZ Measurement of single transverse spin asymmetry AN in forward neutron production at PHENIX(Experimental confirmation of longitudinally polarized proton beams at PHENIX) Abhay Deshpande RIKEN BNL Research Center

  2. RHIC Spin Physics Program Transverse single/double spin physics Quark Flavor polarization Gluon Polarization p0 Production: A. Bazilevsky Sivers vs. Collins effects & physics of higher twists W physics Separate du/u , dd/d from Dubar/u and ddbar/d Longitudinal single spin physics Heavy Flavors Transverse single spin physics Phenix-Local Polarimetry Prompt Photon

  3. Relativistic Heavy Ion Collider BRAHMS & PP2PP (p) PHENIX (p) STAR (p) RHIC pC Polarimeters Absolute Polarimeter (H jet) 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 RHIC accelerates heavy ions to 100 GeV/A and polarized protons to 100 GeV (250 GeV in future)

  4. Plan of rest of this talk…… • RHIC Spin Program • Relativistic Heavy Ion Collider (RHIC) 2001-2002 • PHENIX local polarimetry R&D Run 2 2002-2003 • PHENIX local polarimeter Run 3 • Spin rotator commissioning • Spin monitoring during Run 3 • Summary

  5. Local Polarimeter at IP12 2001/2 • RUN-2: Neutron asymmetry observed in IP12 while testing a local polarimeter designed to look for p0, g asymmetries: • “Left-Right” asymmetry measured for different slices in F:

  6. RUN 2 Neutron Asymmetry IP12 • Successful measurement of forward neutron asymmetry. • Large asymmetry gives good figure of merit for local (PHENIX) polarimetry. • Do not understand physics origin but large analyzing power Y. Fukao et al., "Proceedings of the 15th International Spin Physics Symposium (SPIN2002)

  7. PHENIX Local Polarimeter 2003 PHENIX Collision Point ～1800cm 10cm (±2mrad) Blue beam Yellow beam Dx magnet Zero Degree Calorimeter (ZDC) Tungsten-Fiber Sandwich 5.1 lT, 149 X0 3 ZDCs each side Shower Max Detector (SMD) Plastic Scint. strips (0.5cm x 3) 10 and 15 cm long 7 x 1.5cm columns 8 x 1.5cm rows Read by Hamamatsu M16 SMD beam

  8. Run 3: Loc.Pol. Operation • Energy/SMD strip  Energy Deposit Profile  hit position  determine left/right and up/down & on the F plot • Max Amplitude at F = p/2, –p/2 Left/Right asymmetry  Transverse • Max Amplitude at F = 0 Up/Down asymmetry  Transverse radial • Flat curve  No asymmetry  Longitudinal

  9. Spin Rotator Commissioning (I) Max at F = +/- p/2  Transverse BLUE YELLOW (Raw Asymmetry) / (beam pol.) F F Max at F = 0  Transverse Radial ! Spin Rot PS wired wrong! YELLOW BLUE F F

  10. Longitudinal at last! (Raw Asymmetry) / (beam pol.) (Raw Asymmetry) / (beam pol.) Pbeam = 36% Pbeam = 37% BLUE YELLOW ø ø

  11. How longitudinal were the beams? PHENIX Local Polarimeter measures ST Left-Right vs. Fill No. Up-Down vs. Fill No.

  12. Summary 2002 • Employing the accidental discovery of neutron asymmetry (IP12, 2001-2) PHENIX local polarimetry was designed, constructed 2003 • PHENIX spin rotators were commissioned • Longitudinal orientation of spin monitored • Stay tuned to A. Bazilevsky’s talk on p0 ALL Future Understanding the physics origins of this asymmetry

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