Adrian also noted that the ROCs slept frequently. I just started a
test run to make sure the only problem with ER was the lack of disk
space. The tube HVs are on, the cosmics trigger is still loaded. I
noticed that the event size was around 4kB; should be more like 0.5kB.
So for a trigger rate of 150Hz (what I saw before sleep), the data rate
was over 400kB/sec. This will definitely cause one or the other ROC to
sleep.
I am guessing the event size is so large because the wire chamber low
voltage power supply is off but the thresholds are set. Then you get a
lot of noise from the chambers. If you are just interested in
phototubes, you can disconnect the cable (two-pin ribbon) to the drift
chamber TDC stops in the back of each FASTBUS crate. Then you'll get no
chamber data at all. Just remember to put the cables back when you're
done!!!
Karen
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