User name R. Michaels
Log entry time 15:24:58 on June26,2001
Entry number 64690
keyword=re: multiple peaks in R-arm S1 pad 1RBodo Reitz and I took the chance during restricted access to check
why there are double peaks in the R-arm scintillator for plane 2,
paddle 1, R-PMT, as has been noted in previous halog's. Unfortunately
we could not discover a problem using scope. E.g. we trigger on T1
and see that there is always something on plane 1 and 2 present. We tried
other triggering too. We offer to setup the programmable digital scope
to try to "trap" data with the signature... we can do this in July break, or
whenever we can. Some more info about the signature:
1. The 2nd peak near TDC value 2200 seems to have zero hits in VDCs.
This is what fig 1 establishes. Top left, Nvdc hits for normal TDC value,
top right Nvdc for TDC near 2200. Bottom left, TDC values if >0 VDC hits,
Bottom right, TDC values if 0 VDC hits. (Some cosmics are dirty too).
2. The TDC hits near 2200 have large amplitude in ADC, see fig 2.
I think this contradicts what xfzhu said, so it may be worth double checking.
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We also observed a fairly large rate of after pulsing in PMTs. Did not measure
the probability accurately, but it was "by eye" around 10%. But we cannot cook
up a theory for this to explain the apparent noise in the trigger.
FIGURE 1
FIGURE 2
