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User name johna
Log entry time 12:11:26 on June 14,2003
Entry number 62198
Followups:
keyword=Fast raster pedestals may be wrong for run 46534
The detector replay of run 46534 gave the following errors:
FRPED: peds give = 3939.39 realevents give = 3795.80
FRPED: peds give = 3892.96 realevents give = 3739.50
Since the raster is at a fixed frequency, and since the pedestal triggers come at a fixed frequency, it is possible for them to be 'in phase', such that the pedestals do not sample the full ADC range, thus biassing the pedestal and giving a shift in the position. The pedestals may have to be fixed for this run, using the pedestals from previous runs, or just taking the average fast raster for the whole run, since it is generally a pretty unbiassed measure.