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User name V. Sulkosky
Log entry time 22:33:18 on February 25, 2011
Entry number 348673
keyword=DAQ Deadtime Issue
After leaving the hall, Tai noticed that the DAQ deadtime was high for
cosmics. We were taking only 14 Hz of T1 and 15 Hz of T3 with 1.5 Hz of
T6. The majority of these are EDTM signals, which should cause no real
deadtime. The online deadtime monitor indicates that the deadtime is
about 35%, but the end of run indicates about 62% or so.
I changed CODA configs to what we ran for D-threshold and the deadtime
persisted indicating the problem is probably with one or both HRS's. I
then took some T8 runs with ps8 = 4 and 1. The online DT monitor
indicated that the DT was 0%, but the end of run file indicated that it
was about 36% and 50% respectively. Previously the two were fairly close
to each other.
I also took T1 and T3 only runs. The online monitor again indicated
no deadtime, but the end-of-run showed about 40%.
We thought perhaps there was some extra counting due to the EDTM for
left and right arm coming near each other since we had about 9 Hz of
EDTM coincidences. I changed the EDTM delays to remove the coincidence
but the deadtime persisted.
David is in the hall checking the HRS's for missing gates.
A copy of this log entry has been emailed to: lselvy,danez,yez,rom,kalyan