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RHIC SPIN: recent progress and future prospects

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RHIC SPIN: recent progress and future prospects

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    1. RHIC SPIN: recent progress and future prospects Alessandro Bravar

    2. Physics @ RHIC Study of QCD in extreme conditions heavy ion physics - hot and dense limit spin physics - high Q2 with spin d.o.f. Heavy Ion Physics search for a new state of matter – the Quark Gluon Plasma characterize its properties Spin Physics elucidate the spin structure of the nucleon search for physics beyond standard model

    3. Proton Spin “puzzle”

    4. Program

    5. Hadron – Hadron Collisions

    6. Spin Asymmetries

    7. RHIC: the “Polarized” Collider

    8. The RHIC Experiments

    9. Spin Running in RHIC

    10. A typical RHIC store

    11. RHIC Polarization Run ‘04

    12. Detector

    13. Detector: New Elements

    14. TPC Event

    15. STAR Beam-Beam Counters

    16. Spin Asymmetry Measurements

    17. Relative Luminosity Measurements

    18. Spin Rotators and Longitudinal Polar.

    19. DG from Inclusive Jets Mixture of gg / gq / qq scatterings sensitive to gluon polarization large “-section ® high statistics with low L STAR reconstructs jets via TPC pT for charged hadrons + EMC ET for EM showers

    20. ……- - - p0 “-section @ mid rapidity

    21. First ALL measurement from

    22. Prompt Photon Production

    23. Forward ?0 Production: s & AN Spin dependent initial partonic transverse momentum - Sivers Spin dependent transverse momentum kick in fragmentation - CollinsSpin dependent initial partonic transverse momentum - Sivers Spin dependent transverse momentum kick in fragmentation - Collins

    24. Spin Dynamics

    25. AGS Polarization during acceleration

    26. Imperfection Resonances: Gg = n

    27. Intrinsic Resonances: Gg = nP + n

    28. Siberian Snake Operation Partial Snake (AGS) rotate around beam direction compensate for imperfections use an RF dipole to compensate for intrinsic resonances Full Snake (with 2 rotators - RHIC) rotate around two orthogonal axes in the accelerator plane (i.e. x and y comp. separately) compensate for imperfections and intrinsic resonances

    29. New Helical Snake in AGS

    30. Polarimetry : Impact on Spin Physics measured spin asymmetries normalized by PB to extract Physics Spin Observables RHIC Spin Program requires DPbeam / Pbeam ~ 0.05 normalization Ž scale uncertainty polarimetric process with large s and known AN pC elastic scattering in CNI region, AN almost calculable, but small ~ 1 – 2 % fast measurements requires absolute calibration ® polarized gas jet target

    31. Elastic pC ® pC scattering at low t

    32. AN: from where does it come?

    33. RHIC pC Polarimeters

    34. Performance

    35. Si Detector and Energy Loss

    36. DAQ and WFD

    37. p­C raw asymmetry at 24.3 GeV

    38. RHIC polarization profile large polarization profile in vertical direction (small profile in horizontal) observed position dependent fluctuation in polarization measurements an issue for “calibration”: the JET integrates over the full beam profile the pC CNI polarimeter measures the beam center

    39. The Absolute pp Polarimeter

    40. The Atomic H Beam Source

    41. JET target polarization

    42. The Road to Pbeam with the JET target Requires several independent measurements 0 JET target polarization Ptarget (Breit-Rabi polarimeter) 1 AN for elastic pp in CNI region: AN = - 1 / Ptarget eN’ 2 Pbeam = 1 / AN eN” 1 & 2 can be combined in a single measurement: Pbeam / Ptarget = - eN’ / eN” “self calibration” works for elastic scattering only 3 CALIBRATION: ANpC for pC CNI polarimeter in covered kinematical range: ANpC = 1 / Pbeam eN”’ (1 +) 2 + 3 measured simultaneously with several insertions of carbon target 4 BEAM POLARIZATION: Pbeam = 1 / ANpC eN”” to experiments at each step pick-up some measurement errors:

    43. Recoil spectrometer

    44. pp elastic data collected

    45. Energy - Position correlations

    46. Event selections

    47. “ONLINE” polarization & Results

    48. Summary and outlook: accelerator RHIC Spin Program well under way Successfully demonstrated accelaration, storage, and collisions of polarized protons up to 100 GeV All accelerator components for spin in place and commissioned Expect cold snake in AGS next year (last missing piece) Substantial progress has been made in improving PBeam: PBeam = 40% in both rings almost no loss during acceleration in RHIC Luminosity: ~ 1 pb-1 / week (equivalent) achieved Polarimetry fast and reliable, < 30 sec. measurement time steady progress in understanding and addressing systematic issues JET target operated beautifully in 2004, absolute calibration under way High Polarization (PBeam ~ 70%) and Luminosity (several pb-1 / week) in a few years

    49. Summary and Outlook: experiments All spin experiments work beautifully Major – 1st generation upgrades (almost) completed for Spin Physics New Spin Physics results already extracted from the first p + p collisions in 2002 and 2003 Plan for a long (10 weeks) Spin Run in ’05: L ~ 10 pb-1 with PBeam > 40% DG from inclusive JET and p0 production Long term plan: (continuous effort for luminosity and polarization development needed) Measurements with rare probes: ALL(? + jet), ALPV(W±) and transversity via mid-rapidity jet fragmentation

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