The shift began with a CODA problem as I tried to take some flasher data
before the beam was ready for the WCs. Scaler rate was 8 Hz with flasher
but the coda rate was 3Hz. Double checked with cosmics trigger of 50Hz -
still only 3 Hz on scalers. Called Karen and attempted to run TS in no
strobed mode but this led to a different problem possibly dealing with the
non-strobed crl file. Went back to strobed mode. Checked output of
strobe (retimingOR) with scope - it was there before the cable delay but
not after. Check that the cable delay connections were fine and upon
touching the cable for this action the strobe came back and coda starting
reading events! So the strobe cables may be a bit sensitive.
Re-verified that the flasher signal does not make it through the linear
adders for the Cerenkovs without being attenuated. In fact, for a box
with all tubes on, the flasher signal on the scope is lower than for a
single tube of that box.
Started manually gain matching tubes within Left Cerenkov Box 0. Starting
with voltages set nominally to -2000V a target signal of -3V on teh scope
was set. With this in mind the voltages for LCer0 were set as follows:
top0: -2100V
top1: -2250V
top3: -2200V
bot0: -1850V
bot1: -2100V
bot2: -2200V
To see this effect I decided to try and get adc data for the individual
tubes. I plugged the first four tubes listed above into the splitter
inputs for LCer0, LCer1, LCer2, LCer3 boxes respectively. Since Doug's
trigger rate was low (10Hz) I could not use a flasher trigger as this
would swamp Doug with unwanted flasher data.
It was noted that the scaler readout for these four tubes was not
promising as they varied by a factor of four or so. The first run taken
was 1852. Unfortunately for this run the adc means ranged from 200 to 387
which is clearly pedestal.
Don't know why this is.
Got a chance to take purely flasher data for a bit as the WC folks were
waiting for Cheever to make some adjustments. Still saw what looked like
only pedestal for these single Cerenkov tubes. I have yet to look at the
adc spectra for this entire box with the above voltage settings.
Pete
-------------------------------
Pete Karpius
Graduate Research Assistant
Nuclear Physics Group
University of New Hampshire
phone: (603)862-1220
FAX: (603)862-2998
email: karpiusp@einstein.unh.edu
http://pubpages.unh.edu/~pkarpius/homepage.htm
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