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Hiromi Okada from RIKEN I. Alekseev, A. Bravar, G. Bunce,

Measurement of the Analyzing Power A N in pp elastic scattering in the CNI region with a Polarized Atomic Hydrogen Gas Jet Target. Hiromi Okada from RIKEN I. Alekseev, A. Bravar, G. Bunce, S. Dhawan, O. Eyser, R. Gill, W. Haeberli, O. Jinnouchi, A. Khodinov,

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Hiromi Okada from RIKEN I. Alekseev, A. Bravar, G. Bunce,

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  1. Measurement of the Analyzing Power AN in pp elastic scattering in the CNI region with a Polarized Atomic Hydrogen Gas Jet Target Hiromi Okada from RIKEN I. Alekseev, A. Bravar, G. Bunce, S. Dhawan, O. Eyser, R. Gill, W. Haeberli, O. Jinnouchi, A. Khodinov, K. Kurita, Z. Li, Y. Makdisi, I. Nakagawa, A. Nass, S. Rescia, N. Saito, H. Spinka, E. Stephenson, D. Svirida, T. Wise, A. Zelenski

  2. Forward scattered proton proton target Polarized atomic hydrogen gas jet target RHIC proton beam recoil proton measure! RHIC polarized proton beam RHIC (Relativistic Heavy Ion Collider) in Brookhaven National Laboratory • RUN4 -JET commissioning • (2004 April 26th -May 14th) • H-Jet target pol. ; 0.924  0.018! • 0.0015 < -t < 0.03 (GeV/c)2 • Data taking: • 100GeV/c proton beam (s=13.7 GeV) • 90hours, 4.3M elastic events • PLB 638 (2006),450-454 • 24GeV/c proton beam (s=6.9 GeV) • 16 hours, 0.8M elastic events Polarized proton beam

  3. Forward scattered proton proton target recoil proton  measure! RHIC proton beam R pp elastic event selection and –t measurement R big  TR big  fast protons RHIC beam #16 ch#1 • Every channel measures TR & ToF of recoil particles. • Channel # corresponds to recoil angle R • 2 correlations (TR & ToF ) and (TR & R )  Elastic event selection

  4. Transverse spin dependent asymmetries of pp elastic scattering as a function of -t Forward scattered proton • Single spin asymmetry • Double spin asymmetry proton beam proton target Recoil proton

  5. Single spin asymmetry Double spin asymmetry Physics topics of pp elastic scattering in the CNI region • Described using Helicity Amplitudes 1~ 5 • Interaction matrix M; Nuclear + Coulomb force • Nuclear and Coulombforces become similar in size at –t~10-3 (GeV/c)2. • They interfere with each other Coulomb Nuclear Interference spin non–flip double spin flip spin non–flip double spin flip single spin flip Well known Unpolarized pp elastic scattering experiment  Very small No one photon exchange contribution to ANN.  Sensitive to 5had and 2had !

  6. Results of AN in the CNI region @ s=13.7 GeV s=13.7 GeV PLB 638 (2006), 450-454 |r5| =0 Set r5 as free parameter:  2/ndf = 11.1/12  Im r5 = 0.015  0.029  Re r5 = 0.0008  0.0091  |r5| is consistent with zero! One photon exchange contribution! • Compare measured AN and expected curve with |r5| =0  2/ndf = 13.4/14, |r5| is consistent with zero! 5hadis consistent with zero at s = 13.7 GeV.

  7. AN and r5 results at s= 6.9 GeV • 0.8 M ppelastic events. • Errors on the data points are statistics only. • Components of systematic errors • Acceptance asymmetry • Background correction • Elastic event selection • Set r5 as free parameter •  Im r5 = 0.152  0.014 •  Re r5 = 0.045  0.038 • 2/ndf = 2.87/7 preliminary s=6.9 GeV |r5|=0 • r5 is not zero at s=6.9 GeV ! 2/ndf = 35.5/9 • r5 has s dependence ?  Not improbable; theoretical prediction using ANpC @24GeV/c, 100GeV/c and AN @100GeV/c.

  8. AN collection in the CNI region Pbeam=24 GeV/c Pbeam=100 GeV/c PLB 638 (2006), 450-454 ANpp |r5|=0 |r5|=0 preliminary Theoretical interpretation is undergoing! Next inputs: RUN6 Pbeam = 31 GeV/c, more statistics Pbeam=21.7 GeV/c J. Tojo et al. PRL 89, 052302 (2002) Pbeam=100 GeV/c O. Jinnouchi et al. |r5|=0 ANpC |r5|=0 preliminary

  9. Errors on the data points are statistics only • Components of systematic errors • Relative luminosity of RHIC-beam and H-jet-target • Polarization of RHIC-beam • Background correction • Event selection preliminary • Mean value for all –t range: • <ANN> = -0.0056  0.0036 at s = 6.9 GeV •  Consistent with <ANN> = -0.0024  0.0015 at s = 13.7 GeV ANN results at s=6.9 and 13.7 GeV No one photon exchange contribution to ANN. Sensitive to 5had and 2had !

  10. Summary • We measured AN and ANN by use of the polarized hydrogen gas jet target and RHIC polarized proton beam • 0.001 < -t < 0.032 (GeV/c)2 • Target polarization ; 0.924  0.018 • s=13.7 GeV, 4.3M elastic events (90hours) : RHIC 100GeV/c beam • s=6.9 GeV, 0.8M elastic events (16hours) : RHIC 24GeV/c beam • We compared AN with no hadronic spin-flip • 2/ndf = 13.4/14 at s = 13.7 GeV. • 2/ndf = 35.5/9 at s = 6.9 GeV. • Extracted r5 from AN data • r5at s = 13.7 GeV is consistent with zero. • r5 at s = 6.9 GeV is not zero. • ANNdata are consistent with zero • <ANN> = -0.0024  0.0015 at s = 13.7 GeV • <ANN> = -0.0056  0.0036 at s = 6.9 GeV r5 has s dependence

  11. Helicity amplitudes pC elastic scattering andr5pC Analogy to pp helicity amplitude formalism pC process being described by two amplitudes Non-flip Spin flip Phys. Rev. D64, 034004

  12. pp 100 GeV/c pC 21.7 GeV/c 24 GeV/c r5pCµ Fshad / Im F0had Re r5 = 0.088 ± 0.058 Im r5 = -0.161 ± 0.226 Theoretical interpretation is undergoing! Next inputs: RUN6 s = 7.6 GeV data ~1 week (31 GeV/c beam)

  13. Theoretical prediction of 24GeV/c AN From Larry Trueman (BNL) ANpC @ 24GeV/c, 100GeV/c Pomeron AN @ 100GeV/c  ,  Next inputs: RUN6 s = 7.6 GeV data ~1 week (31 GeV/c beam)

  14. 5had Expected theoretical AN curve without 5had AN & ANN data s dependence of 2had, 5had ?

  15. Si detectors (8cm * 5cm)*3* L-R sides Strip runs vertical with beam 1ch width = 4mm (400strips) 8cm 5cm Recoil particle JET 80cm Channel # corresponds to recoil angle Each channel measures Energy and TOF left Si detectors Polarized Atomic Hydrogen Gas Jet Target System JET target FWHM ~6.5mm RHIC 24, 100GeV/c proton beam ~1mm Recoil particle right

  16. = 0.20 = 0.25 = 0.30

  17. RAW asymmetry for the target polarization Statistical Errors ONLY 24GeV s=6.9, 0.76M event 100GeV s=13.7, 4.2M event 138Gd 241Am 138Gd 241Am Compare 100GeV and 24GeV results using the same binning as 100GeV. (Un-polarized backgrounds ( sources, beam-origin background) are not corrected.)

  18. 24GeV 100GeV Re-binning of 24GeV data 241Am 138Gd 241Am 138Gd • I set 9 bins as a new binning. • #1 - #5 : Full-deposit region • #6 : Mixture region • #7 - #9: Punch-through region (Un-polarized backgrounds ( sources, beam-origin background) are not corrected.)

  19. Because the recoil angle is slightly different depending on RHIC beam energy, 24GeV case is worse than 100GeV case.

  20. What are B ,  and tot ? From experimental results, we can write hadronic elastic cross section in the small |t| region as Hadronic field Coulombic field

  21. ANpp results at s=19.4 GeV, 200GeV Statistical errors only CNI curve (no hadronic spin-flip) N.H. Buttimore et al. PRD 59, 114010 (1999) NEXT: RUN6 s = 7.6 GeV data ~1 week (Pbeam = 31 GeV/c)

  22. Waveform INTG: Waveform　は一定の形なので、最大振幅値読み取り精度を上げるため、決まった区間を積分する。 Tmeas: 最大振幅の1/4のタイミング INTG vs. Tmeasの相関 (1ch分)

  23. Backgrounds • Empty target+ beam • Beam origin • Calibration  source • Empty target, No-RHIC beam： • Calibration  source

  24. Ch#1-16 #16 R Ch#1 （ToF カット済み）

  25. Energy calibration • TR > 8MeV • Detector thickness • TR ~ 0.2 MeV Punch through • 5 < TR < 8MeV • TR ~ 0.2 MeV • 1 < TR < 5MeV • TR ~ 0.06 MeV Mix region • 0.6 < TR < 1MeV • Entrance-window • TR ~ 0.08 MeV Full absorption

  26. Recoil particle identification (ToF 8) nsec  recoil proton Blue area; (ToF 8) nsec Red line：expected recoil mass spectrum from ToF and TR resolition.

  27. (2) Forward scattered particle identification: missing mass Select proper channels for every TRbin. Blue area： ”selected” channels Red line：Expected missing mass spectrum from TR and R resoultion.

  28. バックグランド補正 • “pp弾性散乱イベント”として選択されたイベントに含まれるもの • 本物のpp弾性散乱イベント • 水素標的の中心部分とRHICビームの衝突による弾性散乱イベント • TRR2 (ch#)2　の強い相関あり • 水素標的のテイル部分とRHICビームの衝突による弾性散乱イベント • TRR2 (ch#)2の強い相関ない • 水素標的の偏極度0.9240.018　はテイル部分も含めて算出している • Inelastic events • pp (p+) p etc, • negligible • Calibration  fluctions • Beam orogins Background correction2~3 %

  29. Inelastic events We can distinguish between elastic events and inelastic events by use of recoil angle!

  30. Spin dependent asymmetries effects of spin dependent intensity are smaller than statistical error of NN.

  31. combine How to get Pbeam ? Fluctuation is included in systematic error

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