H(e,e’p) Analysis

Chris Crawford

Blast Analysis Meeting

2004/09/24

Outline

elastic cuts Helastic

based on Dec out-bending Hcbc – wire chambers

for April in-bending data Hpt – TOF elastic

new timing offsets for Feb,April data

background

comparison of yields TOF only, WC

AL,R, GE/GM , PbPt

projected errors

Hcbc – Wire Chambers

[p,,,z]e, [p,,,z]p ) ,,z (5 extras)

pe:e pp:p e:p e:p ze:zp pmiss

need better resolution (current re-crunch)

Timing Offsets

flasher unstable for April runs

retiming method refit flasher peaks aligned elastic timing

peak in sets of 5k events overall relative offsets

from cosmics use WC to extract

position offsets, slope

secondary peak

Hpt TOF elastic cuts

cut on 48 TOF paddle combinations/side

fit (ptr+ptl):(ttr-ttl) to 2-d gaussian

elliptical cuts with parameter n

Background Comparison

Helastic

Hcbc

Hpt

2.4 3.2 5.5 7.6 7.7 7.9

2.2 2.9 4.8 7.1 6.9 7.5

.46 .47 .54 .53 1.3 .30

.56 .59 .46 .62 .73 1.3

.32 .29 .36 .52 .68 .65

.39 .32 .35 .44 .62 .96

3.1 4.0 1.1 .36 .15 .07

2.9 3.3 1.0 .37 .16 .08

1.5 2.7 .81 .26 .11 .03

1.6 2.3 .81 .25 .08 .03

background (%) # events/C

3.8 5.0 1.4 .49 .20 .08

3.8 4.1 1.4 .49 .21 .10

Yields Comparison

TOF cuts only (lr ntuple)

MC includes WC acceptance (see forward paddles)

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 Datasets with Projected Errors

based on additional 325kC of data

32% increase in density 3.2£ reduction in errors

compared with 50kC in April