Hi,
I found the following interesting thing about wire chamber calibration
and resolution.
With k-factors revived, AND theta correction activated. We in fact are
looking at improved resolutions. The comparison with current setup for
online crunching is:
current improved
k-factor only for tracks with beta<0.9 for all
theta correction not used used
I believe the "improved" calibration has also the advantage of being
easier to retionalize than the current approach which treats slow and fast
tracks differently.
Some more details including the fact that k-factors calibrated in Feburary
do not really fit data since May. I have made a new set of k-factor
calibration based on a score of July runs and they seem to improve
resolution for June/July/Aug H2 runs.
I list results here for some H2 runs I can find:
dP_e dtheta dphi dz dP_p dE_beam
6451-6452 (Apr 10): 21 0.50 0.63 1.0cm 22 28
21 0.53 22 27
6992( Apr 23): 24 0.51 0.59 1.0cm 20 28
19 0.48 23 29
8372-8375 (Jun 20): 27 0.54 0.64 1.2cm 24 33
24 0.56 23 29
8868-8870 (Jul 23): 30 0.63 0.65 1.5cm 29 41
28 0.61 28 38
9854-9864 (Aug 08): 28 0.58 0.65 1.3cm 28 34
27 0.57 21 35
For these runs, the April ones are crunched with k-factors calibrated in
Feb (Wire.Cal v1.6). The rest are crunched with k-factors newly calibrated
off July runs.
angular resolutions are improved from the >~1 degree level we currently
have. electron momentum resolution is also improved and is comparable to
the best we have ever seen in past. vertex resolution is also improved to
1cm level from the 1.5-2cm we had. Proton resolution is still a bit worse
than the 15MeV we had according to Chris. I believe these figures overall
are an improvement.
I believe with more work devoted into calibrations(Eugine, Chris,
Taylan and me) it is very likely the resolutions would improve on top of
this level.
I also want to point out that we did not have ANY H2 runs for the entire
May. So it is a little hard to determine how the calibration worked for
that period of time.
I would like to repeat the observation made in one of the "big" analysis
meeting last summer, when I presented the change in time of WC resolution,
periodically running H2 is necessary. Unfortunately, we were very deep in
the deuterium data rush.
In the end, recrunch from DST using this new set of "calibration" will
give us the improved resolution.
Chi
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