R-HRS Deadtime Check

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User name V. Sulkosky/J. St. John

Log entry time 15:10:07 on May 07, 2009

Entry number 271513

keyword=R-HRS Deadtime Check

We checked the deadtime from the R-HRS as reported from datamon,
end-of-run scalers and offline analysis:

Run     Description         Datamon   End-of-run     Replay
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
20838   T8 = 100 Hz            0%         6.5%         6.5%
20839   T8 = 1000 Hz           0%         8.6%         8.5%
20840   T1 = 9 Hz              3%         9.0%         9.0%
20841   T2 = 8 Hz             24%         22%          22%

For some reason, with only a T8 trigger, Datamon claims the deadtime is
zero, but both the end-of-run and offline replay shows about 9% with
1 kHz on T8. The calculation for T1 also is inconsistent for some
reason. However, the deadtime for T2 pretty much matches from all three sources, though it is a whopping 20%.
All these runs were taken with RightHRS unbuffered with cosmics, since
beam was off for a while. We also took a run with the gas Cerenkov
turned off 20842, which eliminates T2 and T8. However we didn't see
any difference in the deadtime online or offline.

A copy of this log entry has been emailed to: rom,zhaobo,doug,moffit,jpchen,yqiang,jiang