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User name R. Michaels
Log entry time 14:27:06 on April 07, 2007
Entry number 198074
This entry is a followup to: 197982
keyword=re: low ADC on L-arm
As I just discussed with the shift crew, the L-arm ADCs are low for the probable reason
that the timing is marginal there -- a deliberate choice forced on us by the severe requirement
of reaching beta = 0.21. I don't want to go into the details now (it was explain in a series
of halogs before the experiment), except to say that the choice is either to reach beta = 0.21
or to have wonderful gate timing on L-arm. You can't have both. We did, however, find
good compromises for the TDC timing, so at least that's not marginal.
If you use the scope picture of the ADC gating seen on detector stack, and take into account
the cable delays of the scope inputs, the gate is probably opening right at the start of the
signal for L-arm. But for R-arm it is fine and didn't change since previous running.
After this experiment we will restore normal gate timing on L-arm.
A copy of this log entry has been emailed to: bogdanw@jlab.org,petratos@jlab.org,camsonne@jlab.org