Hi!
The goals for me today were to provide support for Doug (he did not need
me at all, actually) and to take advantage of his breaks in order to
further study the Cerenkovs (the crappiness of the CC signal does not
allow for study with beam and flasher at the same time, without
introducing more uncertainty, in my opinion)..
After discussing with John in the morning, priorities for the day became:
1) try and attenuate the flasher signal directly at the flasher box - the
reason being that for a lot of detectors the attenuators we have are not
enough (signals off the ADC range);
2) manually gain-match individual CC boxes;
The South Hall was not open at all - I only had a quick access to check if
flasher was "ON" - so I could not work on attenuating the flasher signal.
11:30 AM
For the second task, I started by looking at individual CC PMTs on the
scope in the D-tunnel.
Here is what I found, using the CC voltages we used during the summer:
RCC0: TOP 2V BOT 2V
2V 1V
2V 2V
The signals for all the PMTs were jumping all over the scope and looking
very crappy (weird shapes) indeed. John suggested that maybe there are no
electronical terminations... or maybe the voltages for this box were too
high, generating a lot of noise.
It was very hard to come up with the above figures, the signals were
jumping frequently from 2 to 7 V etc...
RCC1: TOP 0.6V BOT 0.4V
0.6V 0.4V
0.3V 0.4V
... ...
(the copy I made after the logbook missed the last 2 PMTs, sorry! They
were in the same ballpark - all numbers are in the logbook).
At this point, I concluded that the difference between the first two boxes
was due to different attenuator connections (which we do not care about,
as long as we get the same ADCs for electrons)...
2:00 PM
Looking at runs taken by Doug and Pete (the day before), I saw we
were missing LTOF TDCs: went to the D-tunnel, found a cable hanging,
fixed.
3:00 PM
RCC2 TOP: 3V BOT: 3V
2.5V 2V
2.5V 2V jumping
no current drawn 0V - bad tube 2V
2.5V jumping crazy 2V jumping
3V 2V
RCC3 TOP: 1.5V BOT: 1V
1.5V jumping 1V
1.5V jumping crazy 1.5V
1V 1V jumping
1.5V jumping 1V
1.5V 1V
While Doug was taking data, out of curiosity I looked at run 871 taken
in July: the Cerenkov ADCs were very low then too, so it is not like
something happened since then and we lost them...
3:30 PM
Started run 1868 (cosmics + flasher), cosmicWC.settings (no beam in the
ring).
I did not get any TDCs (and because of software cuts, no ADCs either) in
the right sector (both TOFs and CC).
Suspecting RCC deny events, I put them in x-mode, then took run 1869:
DISCREPANCY BETWEEN SCALER RATE (200 Hz) AND CODA RATE (25 Hz)!!! I do not
know what this means (a ROC problem was reported once with this symptom).
Looked at right TDCs, still missing. Mystery left for the next shift...
Adrian
-------------------------------
Adrian Sindile
Research Assistant
Nuclear Physics Group
University of New Hampshire
phone: (603)862-1691
FAX: (603)862-2998
email: asindile@alberti.unh.edu
http://einstein.unh.edu/~adrian/
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