hello..
me and adrian started off with raising the HV. It became apparent
that doing so immediately brings in a "spike" in some of the ADC
spectra. This is not a pedestal and is clearly voltage dependent
We checked if anything could be bad in the electronics (particularly,
if the splitters are sitting out of linear range). Nothing appeared
using cosmics, but we will address this problem tomorrow using the
flasher and changing on hv at the time. I do not understand this but
its either the tubes or the splitter. There is a possibility that the
problem is in the adc (that seems remote).
In the end we agreed to move the ADC spectra from 1200 to only 1300
(where 1300 is the distance from the pedestal peak). That is a 2% HV
change. Only with a well matched setting we can say more about the left
right asymmetry. We also realized that pedestal peaks have changed
over time (the gate length only marginally) by up to about 10%
We have starting HV values and Tavi is carrying over this program until
midnight. After that there are no shift folks.
All plots of today are in a folder in the counting by (we should
keep them for future reference).
Asymmetry: I re-analyzed old cosmic runs and the asymmetry was there as
well. Note that we do not have a beam gate yet and (also
for that) have not done a real scalers analysis.
Field on problems: At the time of the DOE visit it was concluded that
this was not a problem. Unfortunately the shape in
the ADC may not change but the rate definitely does.
In conclusion, we ended up using almost no beam the whole weekend.
regards,
tancredi
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
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