notes from last night's first real running.....

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From: W.J. Llope (llope_at_physics.rice.edu)
Date: Sun Jan 19 2003 - 12:16:57 EST

hi tofp detector experts.....

first, couple of add'l comments from last night's powerup.
then, notes from my first glance at the new data.
finally, proposed action items...

comments please, thanks
        bill

----- powerup:

i alerted CR we're ready to try running at 21:12.

around 00:30, it occurred to me that the shift might not
remember that they're supposed to be controlling the
pVPD power. i called. i was right. they didn't.
alexei & hal then did some tests w/ me on the phone.
PROBLEM - our defaults have disappeared. the shift has
to manually slide up each channel to a voltage.

i get things going i told the shift to simply put all
chs at 2kV. clearly these are not the final gains (proposal
below). i will contact the CR and slow controls people to get
default pvpd hv settings defined as it was last run.
then the shift crew just clicks ON or OFF.....

----- data:

- local trigger efficiency: 3787/19166 = 20%

- pVPD data
        all six chs show ADC and TDC data which looks reasonable
        gains aren't right obviously.

- TOFp data
        i count 5 dead cells and 1 dead fee board (posn #9 again).
        sigh!!!!
        otherwise i see ADC and TDC data which looks O.K.
                *nowhere near* enough hits yet to check gains etc...

- scaler data
        looks fine

- T/C data
        looks fine

- TOFr data
        none seen. hopefully this is only because tofr tripped.

----- action items:

FG - please try to work your HVSys magic. are any of those missing
cells recoverable somehow?

FG - i'm hoping frank can tell me the tofp HV tripped last night...
that is the easist explanation for why there's no data there...

ALL - we need to consider A. a higher TOFr HV current threshold
for now or B. the re-ramping functionality in the caen control code
i asked about a few days ago....

FG - we need a final procedure a.s.a.p. for tofr HV ON/OFF so that
people other than frank are able to check the HV status and repower
this if necessary.

WJL - contact slow controls people and get pvpd default hv settings
back in place.
        i propose the pp gain set, which to remind you is a gain factor
of 8 higher than the so-called set0 (john's original set) based on
john's V**4.64 scaling law....
         1 1800.
         2 1927.
         3 2012.
         4 1764.
         5 2301. -> reduced to 2298 so SC can handle this value.
         6 1886.
it really is a shame we can't get higher than 2300V w/ that CTB 1440!! 

-- 

  W.J. Llope, Ph.D.                      Res. Assoc. Professor
  T.W. Bonner Nuclear Laboratory         phone:  713-348-4741
  Rice University, MS-315                fax:    713-348-5215
  6100 S. Main St.
  Houston, TX 77005-1892
             e-mail:     llope_at_physics.rice.edu
             WWW home:   http://wjllope.rice.edu/default.html

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