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