GEp/GMp Group Meeting

1
GEp/GMp Group Meeting

• Chris Crawford
• May 12, 2005

2
Elastic Cross Section
b target spin angle w/r to the beam line
3
Asymmetry Super-ratio Method

• Beam-Target Double Spin Asymmetry
• Super-ratio
• b 45?

4
i left,right sector j Q2 bin (1..n) b spin
angle

• Single-asymmetry Method
• measure P first, use to calculate R
• model-dependent
• Super-ratio Method
• 2 equations in P, R
• in each Q2 bin j
• independent measure of polarization in each bin!
• 2n parameters Pj, Rj

• Global Fit Method
• fit for P, R1, R2, from all Aij together
• model independent
• better statistics
• n1 parameters
• can also fit for b

5
Cuts

• TOF
• Hpt elliptical cut on timing coplanarity
  hpt-ntuple
• WC
• flr-ntuple ( and track)
• Hwc elliptical cut on 5 redundant WC vars
• Hwd rectangular cut on same
• Hwe cut on invariant mass only (for RC)
• available in utils/cuts_h3.C
• each cut has parameter ns

6
Cosmics TOF Calibration
L 15
L 12
channels
L 9
L 6
L 3
L 0
channels
R 0
R 3
R 6
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TOF Scintillator Cuts
TOF paddle, proton
TOF paddle, electron
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WC Offsets/Resolution/Cuts
pe-pe(qe)
pp-pp(qe)
qp-qp(qe)
pe qe fe ze pp qp fp zp
fp-fp(fe)
z p- z p(ze)
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Tracking Efficiency
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Experimental Spin Asymmetry
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Extractions of m GE/GM
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.Radiative Corrections

• 2.5 sigma W cut 0.2 0.4
• 5.0 sigma W cut 0.4 0.8
• 7.5 sigma W cut 0.6 1.3
• 10. sigma W cut 0.8 2.0
• (predominantly in the left sector asymmetry)

13
Single-Spin Asymmetry
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Systematic Errors

• DQ2 (1.8)
• comparison of qe and qp
• difference between left/rightsector errors
  mostsignificant
• TOF timing will help

• Db (0.8)
• fieldmap 47.1 1
• Hohler 47.5 0.8
• Fit Method 42 3
• (1st 7 bins) 48 4
• T20 analysis 46.5 3

15
TOF Q2

• Q2 2M2(1-g)

16
GE/GM by Dataset
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GE/GM Monte Carlo
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GE/GM Fine Bins
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Beam and Target False Asymmetry
BEAM
TARGET
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Target False Asymmetry
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(No Transcript)
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Systematic Checks

• Monte Carlo
• Time bins

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World Data
World Unpolarized Data
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GE/GM World Data
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GE/GM Results
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Extraction of GE and GM
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GE and GM Results
BLAST World Data