User name R. Michaels
Log entry time 22:59:27 on July27,2006
Entry number 175603
keyword=trigger work, after pulsing, etc
Mike Paolone and I plugged in T1 on L-arm so it doesn't reflect
back. This fixed the R-arm "apparent deadtime" problem.
We looked on the scope on L-arm at the double pulsing. No solid
measurements of these rates, but it seems: PMTs have a high (50+ %)
probability to afterpulse, and trigger T3 has a ~1 % after pulse.
So this would explain a livetime of order 101% for cosmics and
probably for beam too if the prescale factors are high. We noticed
that S0 has no after pulsing. So we decided to do the simplest
thing: create a new trigger T6 which is S0.and.S1.and.S2 using the
MLU which already has these signals with proper timing (note S0
here means the AND of the 2 PMTs on S0). We're setting that up
now. The experiment should still take a fair amount of T3 to
verify/cross-check, plus the fact that sometimes S0 is removed.