Hello, All:
We started out tonight with the power supply off and the wire target at
-0.95mm.
We ran a series of runs to determine where the sense wires HV plateau
started for this gas (Helium Isobutane (70:30)). Those runs were the
following:
run # sense wire HV
1911 3700V
1912 3750V
1917 3775V
1913 3800V
1914 3850V
1915 3900V
1916 3950V
The plateau appears to start at 3800V. At 3775V, a slope in the TDC's was
still visible; however, it had pretty much disappeared entirely by 3800V.
At this point, we turned on the power supply. As to be expected, the wire
position moved, to -1.85mm.
However, now a funny situation arose. From previous nights, I know that
there exists a wire position where trigger rates (using the
elastic_tof_wire.settings trigger (i.e. any of the front 8 TOF's with any
of the back 8)) are around 30Hz or higher. However, tonight, I could not
find that point. As we approached -1.85mm, the lifetime dropped to
5minutes, but the trigger rate never really rose significantly above 10Hz.
As such, data taking was very hard. I managed to take only one run with
the power supply on (run 1919).
Additionally, CODA keep crashing. This seems to happen only when you stop
a run and then wait for about 1 minute or longer before starting a new
run. When you do so, the visual_scal program freezes and so does the
EPICS ca_server. You have to shut all the windows and start all over.
Hopefully, it's just something I'm doing (or not doing), but, if not, it's
quite annoying...
A. Maschinot
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