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    User name R. Michaels

    Log entry time 02:34:38 on March31,2000

    Entry number 37384

    keyword=estimates of trigger efficiency

    With clean (e,e'p) we can measure trigger efficiency fairly
    accurately 3 independent ways for each spectrometer.
    First, a simple estimate from rates give global inefficiency
    E-arm ineff = T2 / (T1 + T5) = 4.8%
    H-arm ineff = T4 / (T3 + T5) = 2.9 %
    But these are upper bounds -- we have to throw out the
    T2 and T4 which are junk.
    A simple judgement is from VDC hits (if empty, event was junk).
    Result: E-arm 1.8% and H-arm 2.1 % inefficient.
    The other ways to measure are from seeing percentage of
    singles triggers which appear to be T5. E.g. T1 have a TC
    peak because the TC start comes from E-arm scint while the
    stop comes from H-arm gate (timed by an H-arm scint if it exists).
    %T1-were-T5 = 2.9%. Then 2.9% * T1 = #T3 missed,
    and #T3-missed/T3 = 2.5% inefficiency of T3. (+/- 0.5%)
    Similarly (%T3-were-T5)*(T3)/T1 = 0.6% = T1 inefficiency.
    One can also use T2,T4 but it requires offline work.