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H(e,e’p) Analysis. Chris Crawford Blast Analysis Meeting 2004/05/21. Monte Carlo Dataset. used DGen, epel channel KINE 10 1. 1. 0. 45. 0. 21. 0. 11. (note .’s) 4 states, q =25 ± 90 ± , f =-17 ± 17 ± gen. 2.5M events ! 1.5M recon (75 bud hrs) momentum resolution: 15 MeV - PowerPoint PPT Presentation
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H(e,e’p) Analysis
Chris Crawford
Blast Analysis Meeting
2004/05/21
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
MC Cross Section
theta
MC Asymmetry
MC Form Factor Ratio
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
Outbending Data (Dec)
Inbending Data(Feb, Apr)
Combined Dataset
Fit of Spin Angle
Spin angle: 35± § 10± (errors also insensitive?)
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
False Asymmetries
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
Track Fit Data vs MC
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
nsed + init.C
Cosmics
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