CNI polarizations in Run09:Summary

A.Bazilevsky For the RHIC CNI Group

March 26, 2010RSC meeting

Run9 results

Released on Feb 4, 2010: http://www4.rcf.bnl.gov/~cnipol/pubdocs/Run09Offline/

Gives: Fill#, Polarization, Stat. error, Syst. ErrorGlobal syst. errors (to all fills)

Short analysis description: NOTE_2009_Polarizations_RHIC.txt

Detailed analysis description: pC_2009.pdf

Briefly

Hjet:Absolute beam polarizationContinuously running in a fillAbsolute stat. uncertainty in a fill: 0.04-0.07~50% fills at s=500 GeV and ~80% fills at s=200 GeV Statistics accumulated in many fills used to normalize pC

pC (two polarimeters in a ring):3-4 measurements in a fill (every 2-3 hours) in target scan modePol. profileMany more parameters: pol. decay in a fill, pol. vector in trans. plane, beam emittance etc.Polarization for experiments (in collisions), after normalization to Hjet and correction for pol. profile

Run9 results

Systematic Errors

Syst. Errors: HJet

Jet normalization, stat: 2.5% for 250 GeV and 1.0% for 100 GeVThat’s what existing data gave us

Jet normalization, syst (dilution): 2%That’s what we’ve been using since Run4 (molecular contribution)

Jet normalization, syst (backgr): 2-3% From the measurements of backgr. asymmetriesRun8: 1.3-2.4%; Run6: 1.3-1.9%

pC: Time dependence in a fill

Time, hrTime, hr

0.68

0.56

0.64

0.49

0.60

0.53

0.62

0.44

0.64

0.52

0.60

0.40

0.70

0.57

0.62

0.54

Pol. decay!

pC: average over a fill

dttL

dttLtPP

fill )(

)()()/exp()( L

decayTttL )/exp()( PdecayTttP

Tpdecay – from pC

TLdecay = 5 hr

Comparison of <P>with TL

decay = 5 hr and (TL

decay = is equivalent to a

weighted average)

Only few fills showed syst. problems assign additional syst. error for these fills

pC in 2009: issues and strategy

Rate related systematicsParticularly at s=500 GeV

Failed to find a way to correct it (rate is defined by prompts which are already cut off by DAQ)

Strategy:Two polarimeters in a ring are averaged

Fill-by-fill systematic uncertainties evaluated from the comparison between two polarimeters and between pC and HJet

Fill dependence (pC vs HJet)

No systematic effect seen on the HJet stat. error level

250 GeV

Fill dependence (pC vs HJet)

No systematic effect seen on the HJet stat. error level

100 GeV

Fill dependence (Pol1 vs Pol2)250 GeV

RMS of the variation 12% fill-by-fill syst. uncertainty

Not yet normalized to HJet

Fill dependence (Pol1 vs Pol2)100 GeV

RMS of the variation 6% fill-by-fill syst. uncertainty

Not yet normalized to HJet

Pol. Profile (all)100 GeV250 GeV

~0.08~0.40

Pol. Profile (good)

100 GeV250 GeV

~0.08~0.40

Pol. Profile: summary

250GeV: <R>=0.360.14; with fill-by-fill variation 0.36100GeV: <R>=0.080.04; with fill-by-fill variation 0.08

<R>=0.360.14 (155)% correction from Hjet to experiments<R>=0.080.04 (42)% correction from Hjet to experiments

Summary

Global systematic uncertainties:

Blue, s=500 GeV: 8.3%Yell, s=500 GeV: 12.1%Blue, s=200 GeV: 4.7%Yell, s=200 GeV: 4.7%

http://www4.rcf.bnl.gov/~cnipol/pubdocs/Run09Offline/

Run5: 5.9% and 6.2%Run6: 4.7% and 4.8%Run8: 4.2% and 7.2%

%4.4

2

2%8.8:200

YB

YB

YB

YB

PP

PP

PP

PPGeVs

%2.9

2

2%5.18:500

YB

YB

YB

YB

PP

PP

PP

PPGeVs

Path Forward

Backup

Sookhyun: Background raw asymmetries

Target Asymmetry (raw)

Beam Asymmetry (raw)

Possible Effect on Polarization

Blue single 250GeV

0.001477+-0.004277

0.003105+-0.004277

<2.1%

Blue double 250GeV

-0.001656+-0.001303

0.003274+-0.001303

<2.2%

Blue 100GeV -0.000704+-0.000734

0.002949+-0.000734

<1.1%

Yellow 250GeV -0.000969+-0.001999

-0.006447+-0.001999

<4.0%

Yellow 100GeV -0.000552+-0.000722

-0.002235+-0.000722

<0.9%

From MeanSigma

pC: pol. Decay in a fills=500 GeV

1/Tdecay

Affected by rates!

<Tdecay> = 10-100 hours

<Tdecay> = 10-100 hours

(<Tdecay>=100 hr 1%/hr)

Run6:

<Tdecay> ~150 hours

Run8:

<Tdecay> ~400 hours

<Tdecay> ~100 hours

In a fill: fit to exp(-t/Tdecay)

pC: pol. Decay in a fills=200 GeV1/Tdecay

<Tdecay> = 50-200 hours

<Tdecay> = 50-200 hours

(<Tdecay>=100 hr 1%/hr)

Run6:

<Tdecay> ~150 hours

Run8:

<Tdecay> ~400 hours

<Tdecay> ~100 hours

Affected by rates!

In a fill: fit to exp(-t/Tdecay)

pC: Time dependence in a fills=500 GeV

Time dependence (pC vs HJet), vs periods=500 GeV

Time dependence (pC vs HJet), vs periods=200 GeV

Pol1 vs Pol2s=200 GeV

Yell

Blue

s=500 GeV

Pol. Profile: rate dependences=200 GeVs=500 GeV

Horizontal component

~5-100||<50

s=200 GeVs=500 GeV

~50||<50

pC: Intensity Profile

Bad profile: Non-gaussianHigh rate

Rate problem?

Good profile: Perfect gaussianLow rate

Bad profile: Non-gaussianLow rate

Target positionig problem?

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

Normalization for pC (Hjet/pC)

Initial normalization from Run4 (s=200 GeV)

AN

pCpp