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    User name R. Michaels

    Log entry time 02:55:14 on May 9,2003

    Entry number 100957

    keyword=R-arm deadtime problems

    I looked at some runs and it seems that the deadtime
    calculation is often nonsense (livetime > 100%. Note, the
    datamon reports 0 in this case.) This has probably been
    happening for awhile. There are two main ingredients in
    this trivial calculation (since one trigger dominates): How
    many T1 were written to tape, and the raw T1 rate.
    Someone should check that the #triggers in the CODA file
    agrees with the #triggers the halog or end-run scalers say
    were recorded. I think there are big disagreements here.
    Examples: run 1818 has 2.02 M events in the file but halog
    says there were 4.19 M. Run 1919 is similar: 1.06M/1.49M.
    Maybe since its late I'm wrong...... someone please check.
    I also note +/- 10% discrepancies in the T1 rate recorded
    on L-arm and R-arm (for some runs where both arms were
    used), though sometimes they agree and the deadtime is
    sensible. It is likely that some ringing or after-pulsing
    is occuring, causing multiple hits in scalers. This can be
    recovered in the case of how many triggers written to tape
    but is potentially unrecoverable for the raw rate, so it needs
    to be checked.