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RHIC Polarimetery in Run9, sqrt (s)=200 GeV

RHIC Polarimetery in Run9, sqrt (s)=200 GeV. A.Bazilevsky for RHIC Polarimetry group RHIC Spin Collaboration Metting May 15 (Friday), 2009. pC Rate history. s=200 GeV. Target changed in Yellow1 to thicker one (from Fill 10686)  Rate problems!

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RHIC Polarimetery in Run9, sqrt (s)=200 GeV

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  1. RHIC Polarimetery in Run9, sqrt(s)=200 GeV A.Bazilevsky for RHIC Polarimetry group RHIC Spin Collaboration Metting May 15 (Friday), 2009

  2. pC Rate history s=200 GeV Target changed in Yellow1 to thicker one (from Fill 10686)  Rate problems! Target changed in both Blues from fill 10732  Blue2 rates slightly increased

  3. pC measurements Online Polarization (%), not normalized (!) vs fill Fills 10616 (Apr 18) – 10749 (May 15) “Online” polarizations: 0.50-0.60 Pol-1 measure slightly lower than Pol-2: by ~6% Blue1/Blue2: consistent within stat. uncertainties Yell1/Yell2: shows variations above stat. uncertainties

  4. pC-BluevsHJet Hjet/pC is stable over fills within (large) stat. errors (of HJet) HJet: <P>=55% (fills 10616-10732) HJet/Blue1  1.05 HJet/Blue2  0.99

  5. pC-Yellow vs HJet Hjet/pC is stable over fills within (large) stat. errors (of HJet) HJet: <P>=55% (fills 10616-10732) HJet/Yell1  1.07 HJet/Yell2  1.00

  6. More precise Hjet-pC comparison Hjet: fills combined in 9 periods Clear correlation between Hjet and pC Consistency vs period within 5% pC-blue HJet pC-yellow HJet

  7. pC: Pol. Profile Polarimeters 2 Polarimeters 1 Horizontal profile Horizontal profile Vertical profile Vertical profile Vertical profile Horizontal profile Usual… R0.15 in previous years (100 GeV beams) R0.1  Experiments see 5% more polarization than Hjet

  8. Backups

  9. Summary • HJet: • Running in stable conditions: <P>~55% • pC: • Blue1 vs Blue2 consistent behavior • Yell1 vs Yell2 show systematic effects ~5-7% (may be due to larger rate effects in Yell1) • pC vs Hjet: consistent within stat. errors • Hjet/Pol1 ~ 1.06; Hjet/Pol2 ~ 1 • Might be ~5% drop in the pC measurements from the beginning to the end of the run due to detector degradation (“dead layer” increase) • Measurements are statistically consistent within a fill • Polarization decay Tdecay ~ 100-200 hours • Polarization profile no sharper than in previous years • Experiments see ~5% more polarization than Hjet • Measurements at injection and flattop are consistent within ~2%

  10. Rate history s=500 GeV

  11. C Mass

  12. P 2. Obtain R directly from the P(I) fit:    I R=0.290.07 pC: Polarization Profile Scan C target over the beam cross: pC 1. Directly measure I and P : P Polarization I Intensity Target Position Precise target positioning is NOT necessary

  13. pC: Consistency within a Fill

  14. pC: Consistency within a Fill Clear polarization decay Consistent between Pol1 and Pol2 10685-Blue 10704-Blue

  15. Statistically Ok !

  16. pC: Consistency within a Fill Prob(2, NDF) – from the fit to a constant in a fill Should be uniform if variations within a fill are only due to stat. errors Should show higher density near 0 if there are “sizable” syst. effects No systematic effects (comparable to stat. errors) are seen within a fill

  17. Pol. Decay In a fill: fit to exp(-t/Tdecay) <Tdecay> = 80-180 hours <Tdecay> = 250-800 hours May need rate correction! • Run6: • <Tdecay> ~150 hours • Run8: • <Tdecay> ~400 hours • <Tdecay> ~100 hours

  18. pC: pol. at injection <P>~56% (similar to flattop) Pol1 measures smaller values than Pol2 by ~5% (similar to flattop, or slightly smaller due to smaller rate effect at injection)

  19. pC: injection vs flattop On the average no difference within 2%: Assuming that we don’t lose polarization on the ramp  AN(inj)/ AN(ftp) is known within 2% Correction due to rate effect and polarization decay at store may be needed Assuming that AN(inj)/ AN(ftp) is correct  Polarization loss on the ramp <2% (-0.91.1)% (3.52.5)% (-1.21.0)% (-2.11.2)%

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