Download - H(e,e’p) Analysis
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H(e,e’p) Analysis
Chris Crawford
Blast Analysis Meeting
2004/05/21
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Monte Carlo Dataset
used DGen, epel channel KINE 10 1. 1. 0. 45. 0. 21. 0. 11. (note .’s) 4 states, =25± 90±, =-17± 17±
gen. 2.5M events ! 1.5M recon (75 bud hrs) momentum resolution: 15 MeV
6th order t2d function (before 2nd bug-fix) standard wire resolution (200!120!400 ) LOSS=1 MULS=1
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MC Cross Section
theta
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MC Asymmetry
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MC Form Factor Ratio
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Fit Method
Super-ratio Method 2 equations in P, R
for fixed bin j
independent polarization in each bin! 2n parameters Pj, Rj
Global Fit Method fit ALj, ARj to above
formalism with P, Rj
n+1 parameters n+2 (+spin angle?)
same advantage as super-ratio method PbPt still cancels
i = left,right
j = Q2 bin (1..n)
= spin angle
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Outbending Data (Dec)
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Inbending Data(Feb, Apr)
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Combined Dataset
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Fit of Spin Angle
Spin angle: 35± § 10± (errors also insensitive?)
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Systematic Errors
4 measured states ) 2 False Asymmetries
Two options: a) assume beam and target symmetric,
use Ab, At to estimate uncertainty in charge b) use measured beam/target asymmetry
to calculation physics asymmetry dilution
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False Asymmetries
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MC Resolution Studies
T2D, bkg 0 200 500 2mm
linear 1.8 3.0 6.7 94
linear, phys 3.5 4.7
6th order 6.6
6th ord, phys 12.8
Momentum Resolution (MeV)
intrinsic wire resolution
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Track Fit Data vs MC
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Tools for Improving Reconstruction/Analysis
0 16 48
8 24 32
40 32 56
wcb_ntuple.C entry for each stub track info (p,,,z) stub coordinates t0-2, x0-2, d0-2 trk in cell, B field
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nsed + init.C
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Cosmics
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Todo List
refine cuts (TOF, CC), subtract background cuts on epics variables (current, WC HV) detector efficiencies w/unpol buffer system more statistics in MC, radiative corrections unfold (z), acceptance dependence of improve WC resolution, do a kinematic fit investigate low value of fit