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The First Measurement of the Elastic pp-scattering Spin Parameters at  s =200 GeV

The First Measurement of the Elastic pp-scattering Spin Parameters at  s =200 GeV. S. Bűeltmann, I. H. Chiang, B. Chrien, A. Drees, R. Gill, W. Guryn*, D. Lynn, J. Landgraf, T.A. Ljubi čič, C. Pearson, P. Pile, A. Rusek, M. Sakitt, S. Tepikian, K. Yip: Brookhaven National Laboratory, USA

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The First Measurement of the Elastic pp-scattering Spin Parameters at  s =200 GeV

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  1. The First Measurement of the Elastic pp-scattering Spin Parameters at s=200 GeV S. Bűeltmann, I. H. Chiang, B. Chrien, A. Drees, R. Gill, W. Guryn*, D. Lynn, J. Landgraf, T.A. Ljubičič, C. Pearson, P. Pile, A. Rusek, M. Sakitt, S. Tepikian, K. Yip: Brookhaven National Laboratory, USA J. Chwastowski, B. Pawlik: Institute of Nuclear Physics, Cracow, Poland M. Haguenauer: Ecole Polytechnique/IN2P3-CNRS, Palaiseau, France A. A. Bogdanov, S.B. Nurushev, M.F Runtzo, M.N.Strikhanov: Moscow Engineering Physics Institute (MEPHI), Moscow, Russia I. G. Alekseev, V. P. Kanavets, L.I. Koroleva, B. V. Morozov, D. N. Svirida: ITEP, Moscow, Russia A.Khodinov, M. Rijssenbeek, L. Whithead, S. Yeung: SUNY Stony Brook, USA K. De, N. Guler, J. Li, N. Őztűrk: University of Texas at Arlington, USA A. Sandacz: Institute for Nuclear Studies, Warsaw, Poland *spokesperson I.G. Alekseev for pp2pp Collaboration SPIN 2006, Kyoto, October 2 - 7, 2006

  2. Helicity amplitudes for spin ½ ½ → ½ ½ Matrix elements: Useful notations: Formalism is well developed, however not much data ! At high energy only AN measured to some extent. Observables: cross sections and spin asymmetries spin non–flip double spin flip spin non–flip double spin flip single spin flip also ASS, ASL, ALL Igor Alekseev (ITEP) for pp2pp

  3. AN & Coulomb nuclear interference The left – right scattering asymmetry AN arises from the interference of the spin non-flip amplitude with the spin flip amplitude (Schwinger) In absence of hadronic spin – flip Contributions AN is exactly calculable (Kopeliovich & Lapidus) Hadronic spin- flip modifies the QED ‘predictions’. Hadronic spin-flip is usually parametrized as: µ(m-1)pµspptot needed phenomenological input: σtot, ρ, δ (diff. of Coulomb-hadronic phases),also for nuclear targets em. and had. formfactors Igor Alekseev (ITEP) for pp2pp

  4. Polarized cross-sections and spin parameters - single spin asymmetry.  - cross-section for one beam fully polarized along normal to the scattering plane. - double spin asymmetry. + - cross-section for both beams fully polarized along the unit vector normal to the scattering plane. ASS has the same definition as ANN, but + is a cross-section for both beams fully polarized along the unit vector in the scattering plane along axis : , where - beam momentum. Cross-section azimutual angular dependence for transversely polarized beams: - blue beam polarization vector - yellow beam polarization vector Igor Alekseev (ITEP) for pp2pp

  5. ANmeasurements in the CNI region pp Analyzing Power pC Analyzing Power E950@BNL p = 21.7 GeV/c PRL89(02)052302 E704@FNAL p = 200 GeV/c PRD48(93)3026 no hadronic spin-flip with hadonic spin-flip no hadronic spin-flip Re r5 = 0.088 ± 0.058 Im r5 = -0.161 ± 0.226 highly anti-correlated Igor Alekseev (ITEP) for pp2pp

  6. AN@ 100 GeV from RHIC HJet Re r5 = -0.0008 ± 0.0091 Im r5 = -0.015 ± 0.029 highly anti-correlated p = 100 GeV/c PLB638(06)450 Igor Alekseev (ITEP) for pp2pp

  7. The setup of PP2PP Igor Alekseev (ITEP) for pp2pp

  8. Si detector package Al strips: 512 (Y), 768 (X), 50µm wide100 µm pitch • 4 planes of 400 µm Silicon microstrip detectors: • 4.5 x 7.5 cm2 sensitive area; • 8 mm trigger scintillator with two PMT readout behind Silicon planes. • Run 2003: new Silicon manufactured by Hamamatsu Photonics. • Only 6 dead strips per 14112 active strips. implanted resistors SVX chips Trigger Scintillator bias ring Detector board guard ring Si 1st stripedge: 490 µm LV regulation Michael Rijssenbeek Igor Alekseev (ITEP) for pp2pp

  9. Elastic events selection Only inner roman pots were used. “OR” of X and Y silicon pairs in each roman pot was used. A match of hit coordinates (x,y) from detectors on the opposite sides of the IP was used to select elastic events. Elastic events loss due to selection criteria < 3.5% Total number of elastic events selected 2.3·106 Note: the background appears enhanced because of the “saturation” of the main band Hit correlations before the cuts t-range Igor Alekseev (ITEP) for pp2pp

  10. Calculation of asymmetry AN Polarized crossection: Square root formula: where Beam polarization: (PB+PY)++/-- = 0.88±0.12, (PB - PY)+-/-+ = -0.05±0.05 Crosscheck: `N (predicted) (PB - PY)+-/-+AN -0.0011  `N (measured)=-0.0016±0.0023 Igor Alekseev (ITEP) for pp2pp

  11. Single spin asymmetry AN Raw asymmetry N for 0.01<|t|<0.03 (GeV/c)2 Statistical errors only Arm AArm B S. Bűeltmann et al. Phys. Lett. B632(2006)167 Igor Alekseev (ITEP) for pp2pp

  12. Fit r5 N. H. Buttimore et. al. Phys. Rev. D59, 114010 (1999) where tc = -8πα/ σtotκ is anomalous magnetic moment of the proton Re r5 = -0.033± 0.035 Im r5 = -0.43± 0.56 our fit no hadronic spin flip Only statistical errors shown Igor Alekseev (ITEP) for pp2pp

  13. Calculation of double spin asymmetries f2/f+=0.05(1+i) E.Leader, T.L.Trueman “The Odderon and spin dependence of high-energy proton-proton scattering”, PR D61, 077504 (2000) f2/f+=0.05 f2/f+=0.05i External normalization using the machine bunch intensities: Lij~IiB·IjY on bunches with given i,j combination Raw asymmetry: Igor Alekseev (ITEP) for pp2pp

  14. Raw double spin asymmetries PB·PY=0.198 ±0.064 Asym|scale=32% Distributions () were fitted with (P1·sin2+ P2·cos2): P1=PB·PY·ASS, P2=PB·PY·ANN and ((P3–P4)·sin2+(P3+P4)·cos2): P3=PB·PY·(ANN+ASS), P4=PB·PY·(ANN–ASS) and (P5+C·t·cos2): P5=PB·PY·ASS, C·t=PB·PY·(ANN–ASS) Statistical errors only PRELIMINARY Igor Alekseev (ITEP) for pp2pp

  15. r2 and r4 At collider energies: Igor Alekseev (ITEP) for pp2pp

  16. r2 and T Im r2 = 0.0019±0.0052 N.H. Buttimore et el. Phys. Rev. D59(1999) 114010 At t0=–0.01 (GeV/c)2: (–t0/tc)=0 and ASS=0.0037±0.0104 Im r2 = 0.0019±0.0052 and T = –0.19±0.53 mb T.L. Trueman hep-ph/0604153 If we assume that only Regge cuts contribute to 2 and 4 then phase of 2 is 90o shifted to the phase of + (Pomeron-Odderon cut exchange). Re r2 = –0.025±0.065 Our results support predictions of none or weak spin coupling of the Odderon Igor Alekseev (ITEP) for pp2pp

  17. Conclusions and plans • Conclusions • The first measurement of AN, ANN and ASS at collider energy: √s=200 GeV, small t • AN is more than 4 different from 0 • AN systematically ≈1σabove CNI curve with no hadronic spin-flip • Double spin asymmetries are consistent with zero, though small contribution of the Odderon is not excluded • What is next ? • Rotate RP1,3 (full acceptance over  !) and move to the STAR IP (spin rotators !!)  (tot, d/dt, b, , AN , ANN , ASS , ALL , ALS): • *=20m, pbeam=100 GeV/c  0.003<|t|<0.02(GeV/c)2; • *=10m, pbeam=250 GeV/c  0.025<|t|<0.12(GeV/c)2. Igor Alekseev (ITEP) for pp2pp

  18. Rotating RP1 and RP3 Full acceptance at s 200 GeV Without IPM and kicker With IPM and kicker 2008 The STAR 3 Year Beam Use Request: Igor Alekseev (ITEP) for pp2pp

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