I have analyzed some data from August run to define hot/dead
channels.
Data from runs 02445, 02446, 02447, 02450 and 02453 have been
used to
define hot wires. Data were taken during test of PACT converter
with digital
input signals. Noise signal from photomultiplier was sent to
shaper and used
as trigger and test signal as well. Beam was off, HV on chambers
were
set to 1900V and threshold was set to 125 mV. So, chamber's data
comprise  noise signals only.

Noise data have been analyzed using most recent (unfinished)
version
of qod21. Data within 800ns time window are included in
the histograms. Total number of triggers is about of 76000. So,
total integration time is about of 0.06s.

Also beam data from run 02456 are taken to compare with a noise
data.
Run 02456 had been taken with beam momentum of 29.8 MeV/c. HVs
on the DCs are
1900V, threshold is 125 mV. Total number of events is 486875.
Data within
800ns time window are included into the plots. Data had been
analyzed
immediately after the run end with of that time version of
qod21.

An attached file shows plots of a noise counts and beam profiles
of
"problem" DC planes where there are one or more channels showing
higher 
or lower than "expected" counting rate. 
The noise counts and beam profile for each DC plane are put next
to each other.
Figure 1 presents data for DC3, DC4 and DC5; figure 2 shows data
for DC8,
DC9 and DC10; figure 3 shows the same histograms for DC13, DC14
and DC16
while figure 4 presents DC18. Rest of the planes did not show
any irregularities
.
Low statistic doesn't allow to define noise level of wires. In
any case
these data should be considered rather qualitative than
quantitative.
(I found some numbers in some histograms are incorrect).
Some channels look very noisy (#16 on DC8, #45 on DC10, #6 on
DC16, #19 and #22 on DC18). Taking into account integrating time
of 0.6s one gets noise rate of channel #16 on DC8 about of 2 kHz
from left
frame. From the right frame for the same channel one finds
(excess is about
of 800 counts, total integrating time is about of 0.39s) noise
rate again is
about 2 kHz.
Channel #5 on DC14 most likely has higher crosstalk level.

Finally, figure 5 shows the "dead" channels. It was found just
one such a
plane DC21 (except planes of DC17, DC23 and DC24). No counts on
channels 17
through 21 except channel 20, where contents is a half of the
expected one.
Most likely this is a "contact" problem. When I checked one of
the runs from
the beginning of the beam test I found all these channels were
alive and
channel 20 had some excess(10-30%?) over the neighbors.


-- 
 --------------------------------------------------------
 Yuri Davydov (davydov@triumf.ca)       (604) 222-1047 ext.6198
 TRIUMF  			  FAX  (604) 222-1074
 4004 Wesbrook Mall
 Vancouver,  BC  Canada   V6T 2A3

Filename: rates.ps.Z.txt

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