From: Glen Warren (gwarren_at_anti-spam)
Date: 05-Jun-2003 09:56:44
GEn01 analysis meeting June 4, 2003
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attended by: Donal, Paul, Oscar at UVa
Hongguo, Frank, Nikolai and Glen at JLab
REPORTS
*) GMn: We agreed to take the average of the Kelly and Basel Gmn and use
the difference as the uncertainty. Thus, Gmn is:
Q2=0.5: 1.013 +- 0.011
Q2=1.0: 1.063 +- 0.018
The approach for the paper will be that we extract Gen assuming
Gmn=Dipole. We will give the number. Next, we will state that we know
Gmn is not dipole, comment that the correction is mostly linear, and
then give an extracted value of Gen. Mostly, it comes down to wording.
*) Background: not results
*) packing fraction for stick 4: Glen was concerned that the packing
fraction for stick 4 doesn't have the proper weighting because the two
cells have different packing fractions. Nikolai said that the p.f. are
event weighted using all of the runs, so the reported p.f. do the proper
averaging.
*) dilution factor for stick 3: Hongguo's needs info on Kel-F.
*) hszbeam cut for Q2=0.5: Glen repeat the hszbeam cut to examine the
4K shield contributions for Q2=0.5. The fit was not stable because of
the smaller tails due to the smaller 4K shield contribution. His
results are consistent with Nikolai's earlier findings, although just
barely. The difficulty performing the fit makes the uncertainties in
this approach large. Conclusion was that we get a smaller uncertainty
for Q2=0.5 using the previous approach (no hszbeam cut, treat 4K shield
as known dilution, don't include in d.f. model).
*) CEX: Marko said that the size of the uncertainties for Q2=1.0 are
much greater than the bin-by-bin dependence, so it is not worth doing a
bin-by-bin correction. We reviewed the CEX bin-by-bin corrections for
Q2=0.5 and reached the same conclusion.
*) paper: Donal gave Glen a copy. Now there will be two people who
don't have much time to work on it.
*) variables to fit: Glen will write down his opinion to give us a
starting point for discussion. Frank also wanted a justification for
binning.
*) kinematic uncertainties: We had a long discussion of exactly what to
do. In the end we reached no conclusions. Glen will discuss matters
with Frank to come up with something agreeable.
*) Q2=0.5 fourth pass: Frank is calling it Fourth pass to be parallel to
Q2=1, even though we do not have a Q2=0.5 third pass. It is about 1/3
done. Frank also noted that it was necessary to modify batchman to work
with the new changes on the farm.
*) Target polarization: Paul has submitted a new file with target
polarization. The biggest difference is the better calculation of the
length of the run. He uses the clock time for the start and the number
of helicity buckets to get the length of the run. He also included
correct B field, LHe level. There are 5 runs in which we He dropped
below the cell and we continued to take data. These runs should be
excluded from analysis.
Paul present a plot showing the differences in the old and new target
polarizations. The biggest differences in polarization occur mostly
when the is a very large change in the length of the run. One curiosity
appeared in that there were a lot of runs that previously had been 1-3
minutes long that were now ~73 m long. Glen thinks that the strong
spike at 73 minutes is quite odd, suggestive of an error. There is also
a broader hump around 35 minutes.
*) pion production contributions: 0.44% for Q2=1. Done by adjusting the
pion production to fit the data without cuts and then look at what
survives the cuts. The issue of how to correct for this arose. We need
to measure the asymmetry, which can be estimated by looking at the
asymmetry for higher W. We need to remove the E' and theta_nq cut to
see these pion events.
*) Dilution Factor uncertainties: Nikolai will give Hongguo rates are
varies target materials for Q2=1 for Hongguo to look at d.f. uncertainties.
TO DO
Donal
*) work on paper.
Glen
*) look at 98 and 01 field setting codes
*) work on paper
*) write down approach of which variables to use for fit.
*) Discuss with Frank the approach to kinematic uncertainties.
Nikolai
*) Give Hongguo rates are various target materials for Q2=1
Frank
*) accidentals
*) pion production asymmetries
Hongguo
*) dilution factor for stick 3 using path lengths thru materials.
*) kinematic uncertainties
*) dilution factor uncertainties
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