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User name Yi Qiang
Log entry time 05:35:34 on February 17, 2009
Entry number 261591
This entry is a followup to: 261389
keyword=More results of BB Gas Chrenkov analysis from run 1479-1482
Those runs were taken after the PMT12 base replacement and other adjustments.
plot 1 shows the TDC spectra of each PMT requiring single track, single
TDC hit and large pre-shower.
plot 2 shows the selection of mirrors, X and Y are projections assuming
mirrors are 0.8m away from the first wire chamber.
plot 3 shows the TDC spectra with mirror selection in addition to the
single track, TDC and preshower cuts. The accidental background drops
plot 4 ADC spectra from each PMTs. The red curve is supposed to be the
signal from electron which requires single track, single TDC hit, large
pre-shower, mirror position and coincidence cut. The blue curve is for
background. In order to select real un-biased background events, except
for the single track I didn't apply any cut on that mirror or PMT.
Instead, I chose the events passing through a mirror, #j, far away from
the interested one, #i: j=21-i. I require single TDC and position cut of
From results I learned the following:
1. The R-HRS side PMTs are fairly quite. The beam line side PMTs suffer
large base/pedestal fluctuation due to higher rates.
2. Roughly speaking, the Gas Cherenkov performance in terms of maximum
number of photon does not vary too much (>factor 3) from mirror to
mirror. The difference of the amplitudes is most likely due to alignment.
3. Mirror 4 has much less events than the others may due to the event
selection. Special attention required.
A copy of this log entry has been emailed to: meziani, bogdanw, brads, xqian, zhangyi, posik, flay, vasulk