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Systems looked at: TOFs, Cherenkovs
Methods: cosmics, flasher
Problems: CODA - crapped out at high rate and never recovered
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Since there was no beam tonight, I chose to work with cosmics and the
flasher on the TOFs - starting the gain fine-tuning. TOF voltages are
the same now - so no worry for the WC group!
First, following John's suggestion, I took a flasher run (1975) to have as
reference for TOF timing, before playing with voltages.
I created then cosmicLTOF.settings and cosmicRTOF.settings - trying to
avoid CODA problems created by high rate from both sectors simultaneosly.
Still, CODA gave me trouble all night - the ROCs were sleeping and I
barely managed to take two runs (1985 - both cosmics and flasher and 1986
- only cosmics) switching between ROC, ROCr and ER modes every 5
seconds... At least this is a starting point for future fine-tuning.
I dropped the TOF tuning since it required CODA and I turned to the
Cherenkovs, at Tancredi's plea for help with this system.
I recorded all the signals from the right sector in the TOF logbook, page
104 - in the D-tunnel I triggered on the photodiode, setting the scope in
"average" mode (last week I had done this triggering on the individual
PMTs and it was nearly impossible to tell the amplitude - signals were
jumping etc.)
In short, signals are everywhere between 0.1 V to 1.3 V, varying by a
factor of 3 on the same box even - but most of the tubes on the same box
are pretty matched.
Anyway, they need fine-tuning and this can be used as a starting point.
Tancredi told me he had discovered light leaks on one left Cerenkov, I
suspect light leaks on the right too, judging by the funny scaler rates
and the crappines of the signals when triggered directly on the PMTs (not
on the photodiode - by the way, even triggering on the photodiode gives
you a flaky signal, Tancredi's suggestion to put the scope on "average"
mode really helped).
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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