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User name R. Michaels
Log entry time 03:17:05 on July 8,2010
Entry number 330748
This entry is a followup to: 330740
keyword=re: strange timing
I investigated a little more the strange timing peaks.
Here's an example.
L.s2.lt and others have two peaks for the event types 4 and 1.
For event type 1 they look like self-timing peaks.
These correspond to two VDC time spectra shifted by 200 units =
100 nsec. A very obnoxious correction. It's as if there were
after-pulsing on the S2 phototubes but I think it's not that simple.
Meanwhile for R-HRS there doesn't seem to be the same double
peaking for the same run (fig 2). T4 is coinc and T3 shows a
self-timing peak. The lack of a jump for R-HRS T4 suggests
there is no after-pulsing in the L1A (gates).
Right now I think there is a flakey module on L-HRS downstream of
the trigger supervisor, involved in the gates.
It would help a lot if we could observe this with cosmics or a pulser
because then it could be isolated during an access.