RHIC CNI Polarimeter status RHIC CNI Group February 26, 2008

 2 /ndf = 6.5/6 33 Hours, 10 stores, 1.4M events Statistics uncertainty only Rough event selection TOF width cut (+/- 10nsec) Channel 2-3 width selection No background correction. HJet: Blue1

Fill#H-Jet Events total P BLUE =0.486  0.023

 2 /ndf = 1.9/6 25 Hours, 3 stores, 1.4M events (Feb ) Statistics uncertainty only Rough event selection TOF width cut (+/- 10nsec) Channel 2-3 width selection No background correction. HJet: Blue2

Fill#Events    total  0.023

HJet: Yellow P YELLOW =0.384  Fill#H-Jet Events total168923

HJet: Yellow  2 /ndf = 9.8/6 31 Hours, 6 stores, 1.7M events Statistics uncertainty only Rough event selection TOF width cut (+/- 10nsec) Channel 2-3 width selection No background correction.

pC: Online Polarizations Only scan measurements at store Measures average polarization over trans. profile This is what directly (should) relate to HJet measurements, but… Absolute scale in not yet fixed A N from Run4! Latest fills not yet included

pC: averaging Mainly in blue: Intensity profile is flat  we stay longer at beam center than at periphery  measured polarization is closer to P max than to /P max ~ 0.93 for blue, see next slides Yellow looks fine for this Latest fills not yet included

Polarization Profile   P(L/L max ): just an example If there are problems with target position determination  Exclude position from calculations: R=0.29  0.07 Latest fills not yet included

Polarization Profile R vs fill ~ 0.28 /P max ~0.88 ~ 0.16: /P max ~ 0.93 Run5/6: R~ 0.10  0.15 Latest fills not yet included

pC vs Hjet HJet-yellow HJet-blue P online (pC)/P(Jet)=1.06  %: C energy correction and cuts (online/fast_offline difference) +7%: change in A N A N from Run4! P online (pC)/P(Jet)=1.17  %: from “bad” scans in this period (flat intensity profiles) +4%: C energy correction and cuts (online/fast_offline difference) +7%: change in A N A N (Run5)/ A N (Run4) ~ 1.01 A N (Run6)/ A N (Run4) ~ 1.15 Latest fills not yet included

Fast offline, normalized to HJet Normalization uncertainty (stat. only) Feb 23Feb 14 Latest fills not yet included

Summary HJet demonstrates very stable/consistent measurements Consistent target asymmetry vs -t (with the same target polarization) Same (and even lower in Run8) background level pC data Polarization profile in blue is similar to Run5/6; polarization profile in yellow is sharper Experiments see more polarization than HJet due to intensity squared weighting: by 7%-relative in blue and by 12%-relative in yellow (if vertical and horizontal profiles are the same!) Blue-online polarizations are overestimated by (17  6)%-relative +7% - from A N (compared to Run4) Yellow-online polarizations are overestimated by (6  6)%-relative +7% - from A N (compared to Run4)

Backups

Hjet: Background level 1.2 <T R <2.5 MeV, 2 hours data YELLOW mode BLUE mode BPM at IR12 reading: Blue (x,y)= (+5, +8)mm Yellow (x,y) = (0,  4)mm, Fill#9920 BPM at IR12 reading: Blue (x,y)= (0,  4)mm Yellow (x,y) = (  10, +10)mm, Fill#9905

pC: Online vs “fast offline” Yellow online polarizations look unbiased compared to online Blue online polarizations are overestimated compared to online by ~4% relative Absolute scale in not yet fixed

pC stability: “Dead Layer”

pC stability: T0