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    User name V. Sulkosky

    Log entry time 10:04:22 on November28,2007

    Entry number 216659

    keyword=Deadtime RHRS runs 21175 to 21193

    I saw in the end-of-run files that the deadtime for the production
    runs taken last night was typically between 50 to 70% for the right
    arm. For run 21193, the prescale factor line is the following:

    PRESCALE FACTORS:ps1=1 ps=12 ps3=16777215 ps4=16777215 ps5=65535 ps6=65535 ps7=65535 ps8=65535

    The ps factor for T2 is not set, "ps=12" should have been "ps2=12".
    This has been the case since run 21175, yesterday morning. I
    corrected the right DAQ prescale.dat file. I believe the DAQ
    interprets this so that T2 has a large prescale factor. I looked at
    run 21183, which has 8105 accepted events, 8292 T1's and 9543 T2's
    from the end-of-run file. In the data file, there are no T2's.
    The deadtime for this run should then be 1 - 8105/8292 = 2.3%.

    It appears the end-of-run file script interprets the ps line to mean
    that the prescale factor for T2 is 1. Hence, the discrepancy in the
    deadtime calculation between datamon and the end-of-run file summary.
    I believe the right arm data taken last night is fine in terms of
    deadtime. However, runs 21175 to 21193 have no T2's.