Due to a unpol D2 run we took this week, I was able to recalibrate
our luminosity
again using fixed crunching (bugs discovered couple of weeks ago).
Finally, for the
first time with a long cell the data shows consistency.
Th ABS data were taken from a "good day", when target was well
conditioned after
the nozzle refreezing. The elastic eD event rate is about the same for
ABS and unpol with
V14 open and buffer pressure 2.0 torr. Assuming we trust unpol, it gives
ABS flux of
F=2.2* 10**16 at/sec.
Comparing the ABS rate with theoretical curve, I got F=1.5*10**16
at/sec. The remainig
30% difference is apparently the real inefficiency of
detection/reconstruction. So we may assume
that F=2.2*10**16, target thickness is 6*10**13 at/cm**2 with detection
efficiency of 70%.
I'd like to add that this efficiency is related to relatively low q
(Theta (e) is around 30 degrees).
At higher q the identification might be a good deal worse, and the issue
of momentum and
angular resolution remains crutial.
Genya
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