Hi all,
after checking my analysis codes, correcting some bugs and playing with
various cuts, a new bin at higher Q2 than shown during last analysis
meeting surfaces. It is to the right of the first Bates 94 data point.
Please see atatched T20_all.ps which is a weighted average of all the data
taken so far, including the Feburary runs when one of the holding field
coils was shorted, and the latest runs after shutdown. The Feb runs are
determined to have spin angle arround 30-31 degrees by fitting asymmetries
in both sectors to theoretical curves for various spin angles.
Also atatched is T20_projection.ps. This projection is done by scaling
up the collected statistics in data. With another 26 weeks running, which
is 4368 calendar hours. Assume 2200 hours of beams(after downtime and dead
time) at current luminosity(80mA, 0.5 events/C). This projects 3.7 times
more data than we have taken since Feburary.
Scale the error bars in real data according to the counts in data and in
projection. Statistical errors thus obtained are then combined with the
data already taken to project the errors for entire Blast running.
It does assume that the current 59% Pzz does not decrease in any case for the
next half a year! the error bars will be almost twice as large if Pzz
decreased to 36% level as before the shutdown.
Note that for the last two data points, I am still not seeing 100% the
counts predicted by the Monte Carlo. Comparison to MC shows that I am
still missing arround half in these two bins. I have to make a few cuts
tighter than at lower Q2 to avoid the e'p events. When detector conditions
become better understood, I expect to catch more ed's in those two bins,
perhaps will be able to split off another bin arround 4.5fm-1.
Chi
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