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User name R. Michaels
Log entry time 13:29:31 on July 4,2010
Entry number 330007
keyword=Trigger 6 coincidence time spectrum
This is already old news I guess, but I didn't see a plot yet
so here it is: the coincidence time spectrum for Trigger 6 (fig 1).
T6 = triple coinc of L-HRS scint + R-HRS scint + R-HRS gas Cerenk
The self timing peak on the left side makes sense in terms of a
simple model (fig 2) for the coinc circuit and the TDC. Normally
the R-HRS Cerenk makes the trigger timing. This produces the
TDC stop. Meanwhile the TDC start in this picture comes from T1
(L-HRS Scint trigger). But if T1 slides late (random coinc) it
eventually makes the trigger timing. Later times corresponds
to smaller values in the TDC because it's a common-stop TDC.
Note, the cut here is D.evtype==6. If you just cut on evtypebits
you'll get a second self-timing peak from T1's that survive prescaling
apparently because T1 arrives earlier than T6 at the trigger supervisor.
The width of the randoms is about 115 units = 57 nsec (about right).
I don't know if the rates make sense, but I think Bogdan said they
I'd still like to make a check: the true coinc peak should disappear with
a simple pulser test. But this looks pretty encouraging so far.