rhic polarimetery in run9, sqrt (s)=200 gev
DESCRIPTION
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! - PowerPoint PPT PresentationTRANSCRIPT
RHIC Polarimetery in Run9, sqrt(s)=200 GeV
A.Bazilevsky for RHIC Polarimetry group
RHIC Spin Collaboration MettingMay 15 (Friday), 2009
pC Rate historys=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
pC measurements
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
Online Polarization (%), not normalized (!) vs fill
pC-Blue vs HJet
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
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
More precise Hjet-pC comparison
Hjet: fills combined in 9 periodsClear correlation between Hjet and pCConsistency vs period within 5%
pC-blueHJet
pC-yellowHJet
pC: Pol. Profile 2
2
P
IR
Polarimeters 2Polarimeters 1
Usual…R0.15 in previous years (100 GeV beams)R0.1 Experiments see 5% more polarization than Hjet
Horizontal profile
Vertical profile
Vertical profile
Vertical profile
Horizontal profile Horizontal profile
Backups
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. errorsHjet/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 yearsExperiments see ~5% more polarization than Hjet
Measurements at injection and flattop are consistent within ~2%
Rate historys=500 GeV
C Mass
pC: Polarization Profile
pC Scan C target over the beam cross:
Target Position
Inte
nsity
Pola
rizati
on
2
2
P
IR
I
P
2. Obtain R directly from the P(I) fit:
2
2
max 2exp)(
P
xPxP
2
2
max 2exp)(
I
xIxI
R
L
LPP
maxmax
P
I
Precise target positioning is NOT necessary
1. Directly measure I and P :
R=0.290.07
pC: Consistency within a Fill
pC: Consistency within a Fill
Clear polarization decay
Consistent between Pol1 and Pol2
10685-Blue10704-Blue
Statistically Ok !
pC: Consistency within 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
Prob(2, NDF) – from the fit to a constant in a fill
No systematic effects (comparable to stat. errors) are seen within a fill
Pol. Decay
<Tdecay> = 80-180 hours
<Tdecay> = 250-800 hours
May need rate correction!
Run6:
<Tdecay> ~150 hours
Run8:
<Tdecay> ~400 hours
<Tdecay> ~100 hours
In a fill: fit to exp(-t/Tdecay)
pC: pol. at injection
Pol1 measures smaller values than Pol2 by ~5%(similar to flattop, or slightly smaller due to smaller rate effect at injection)
<P>~56%(similar to flattop)
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%
(-2.11.2)%
(-0.91.1)%
(-1.21.0)%
(3.52.5)%