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User name R. Michaels
Log entry time 21:57:32 on June16,2009
Entry number 281811
This entry is a followup to: 281789
keyword=Compton activity, part IIIEdet hit plane distributions look bizarre -- big background
that drops off from beam position -- no clear Compton edge.
Slits were fully open, the MCC had reduced laser power.
Will increase laser power, reduce slits to see if the
background improves.
21:38 beam returns. 3 uA, slits not reduced yet
Run 17554
Run 17555 -- mixed conditions (ignore)
21:48 closed slits down. Run 17556. Threshold = 30.
Hit distributions in fig 1.
21:50 stop run. move detector out (to 60 mm)
Will resume high-current running for PVDIS while
we think about what to do -- it seems the background
is enormous at present and there is no hint of
Compton signal.
It might help to trigger on photons with standard
firmware and/or try Michel's firmware which triggers
on photons -- we'll discuss it.
FIGURE 1
