Reading my Hodoscope

My Scilab run finished overnight.  In the stacked (hodoscope) configuration from the overnight run earlier in the week, we got 16,325 "concidences."  False-coincidences (the range for these is still set at 30 to 50 ns) were only 2, so I think we can be confident that almost all of the 16,325 coincidences were "real" (i.e., the result of a particle or particle-shower passing through both detectors).

As a percentage of total pulse count:  The coincidences accounted for 16,325/110,912 = 14.7% of events on PMT1, and 16,325/280,036 = 5.83% of events on PMT2.

The run turns out to have had some interesting variation in the total pulse rate over the course of the run:

Pulse rates from two PMTs hodoscope configuration, from 5:15 pm on Mon. 9/12 to 11:06 am on Tue. 9/13.  Horizontal axis:  Minute in run.  Vertical axis:  Pulses in that minute.  Lower curve: PMT1; Middle curve: PMT2; Upper curve: Sum.

It could possibly be related to ambient light (since this was an overnight run), but I'm unsure whether the shape of the variation really fits with that hypothesis.  Too bad we don't have a light meter that could record the room light levels independently.  Interestingly, the detector with the higher pulse rate also had more (candidate) apparent diurnal variation.  Possibly if we just sealed the gun case better (or threw a blanket over it), the pulse rate would be more in line with the other detector.  I should probably do a test where we see if switching the lights on & off affects it.