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User name R. Feuerbach
Log entry time 09:03:09 on August 19, 2006
Entry number 180884
This entry is a followup to: 180635
keyword=Summary of FPP activity late yesterday
In the morning it was determined the gas for the FPP was "bad", we
thought due to a nearly-empty dewar of Argon. After 4hrs of flushing
with the new Argon bottle the efficiency had not improved, and the VDC's
(which pull from the same Argon source) continued to look fine, leading
us to suspect the gas mixture. Scott and Jack (remotely) investigated
the source of the problem, and determined the gas mixing controller for
the FPP might have a problem, and it was repaired/swapped out around 4pm.
To monitor the chambers recovery, the HV on the chambers was increased
until their efficiency was "normal". Production runs were taken during
the swing and owl shift, and the HV slowly dropped over the night as the
gas recovered. This morning the high voltage on the chambers are 100 to
125V higher than their nominal 1775V, and they are operating well.