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User name Yi Qiang
Log entry time 00:28:46 on February 16, 2009
Entry number 261389
keyword=Analysis of Bigbite Gas Cherenkov
The following analysis was done for mirror 6 (beam line side) using the
data taken before Feb 15 owl's access
The basic cuts used through out this analysis are single track cut and
single TDC hit cut in mirror 6:
Plot 1 shows the two TDC cut I used to select coincident events between
Gas Cherenkov and shower: cut 1 for the shape peak and cut 2 for the
Plot 2 shows the Bigbite tracking projection to the Gas Cherenkov
mirrors, I assumed a 0.8 m distance from first wire chamber to these mirrors.
Plot 3 shows the mirror location with coincidence cut 1. We can clearly
identify mirror 6 and a graphic cut was defined for this mirror. I also
defined a cut for mirror 12 which is far away from mirror 6.
Plot 4 shows the mirror coverage with coincidence cut 2. Looks like that
this coincidence is from the events mainly hitting the two near mirrors,
5 and 7, instead of mirror 6.
Plot 5 shows the TDC spectrum of mirror 6 with geometric cut on mirror 6
and the background basically goes away.
Plot 6 shows the TDC spectrum of mirror 6 with geometric cut on mirror
12. This time the coincidence peak disappears.
Plot 7 shows the ADC spectrum of mirror 6 with geometric cut on mirror 6
and various TDC cuts. With coincidence cut 1, a distribution with fairly
large number of photon electrons shows up. With coincidence cut 2,
because these events share the number of photon electrons with other
mirrors, the peak moves to the lower side. Cutting outside of both
coincidence windows gives pedestal and background only.
A copy of this log entry has been emailed to: meziani, bogdanw, brads, moffit, vasulk, posik, flay