RHIC CNI Polarimeter status RHIC CNI Group February 26, 2008.
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Transcript of RHIC CNI Polarimeter status RHIC CNI Group February 26, 2008.
RHIC CNI Polarimeter status
RHIC CNI GroupFebruary 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
HJet: Blue1Fill# H-Jet Events
9885 50427
9888 94430
9890 37767
9897 72279
9898 176010
9901 21035
9902 162664
9905 179075
9906 358828
9909 213666
total 1366181
PBLUE=0.486 0.023
2/ndf = 1.9/6
25 Hours, 3 stores, 1.4M events (Feb. 24-26)
• Statistics uncertainty only
• Rough event selection
• TOF width cut (+/- 10nsec)
• Channel 2-3 width selection
• No background correction.
HJet: Blue2
HJet: Blue2
Fill# Events <PBLUE>
9942 472968 0.4310.040
9948 401223 0.3870.042
9949 523399 0.4090.036
total 1397590 0.415 0.023
HJet: Yellow
PYELLOW=0.384 0.021
Fill# H-Jet Events
9919 215906
9920 282587
9935 213772
9937 261714
9938 353033
9939 362811
total 168923
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
AN 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 Pmax than to <P>
<P>/Pmax ~ 0.93 for blue, see next slides
Yellow looks fine for this
Latest fills not yet included
Polarization Profile
2
2
max 2exp)(
P
xPxP
2
2
max 2exp)(
I
xIxI
R
LLPP
maxmax
P(L/Lmax): just an example
If there are problems with target position determination Exclude position from calculations:
2
P
IRR=0.290.07
RPP
1
max
Latest fills not yet included
Polarization ProfileR vs fill
2
P
IR
<R> ~ 0.28<P>/Pmax ~0.88
<R> ~ 0.16: <P>/Pmax~ 0.93
Run5/6: R~ 0.100.15
Latest fills not yet included
pC vs Hjet
HJet-yellow
HJet-blue
Ponline(pC)/P(Jet)=1.060.06-1%: C energy correction and cuts (online/fast_offline difference)
+7%: change in AN
AN from Run4!Ponline(pC)/P(Jet)=1.170.06+6%: from “bad” scans in this period (flat intensity profiles)+4%: C energy correction and cuts (online/fast_offline difference)
+7%: change in AN
AN(Run5)/ AN(Run4) ~ 1.01AN(Run6)/ AN(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
SummaryHJet demonstrates very stable/consistent measurements
Consistent target asymmetry vs -t (with the same target polarization)Same (and even lower in Run8) background level
pC dataPolarization 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 (176)%-relative+7% - from AN (compared to Run4)
Yellow-online polarizations are overestimated by (66)%-relative+7% - from AN (compared to Run4)
Backups
Hjet: Background level1.2 <TR <2.5 MeV, 2 hours data
YELLOW mode BLUE modeBLUE modeBPM 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