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    User name R. Michaels

    Log entry time 03:48:29 on June 9,2004

    Entry number 125044

    keyword=run efficiency, run time

    To determine the run time, I pick a weak hole (large scatt. angle)
    and demand 20K events with momentum near the O16 and Hydrogen peaks
    for water cell. Left and Right HRS are similar. Percentage of
    events that point to target is reasonable (at least 75%). Percentage
    of events with the above criteria (hole, momentum) is ~0.5%. So,
    I need 800K events ((20K/0.5% x 2 spectrometers), which at 1 Khz
    DAQ rate takes 13 minutes. Therefore I asked the shift workers to
    take 15 minute runs on Carbon and 1/2 hour runs on water. Given
    the overhead in field changes (1/2 hour) I think we'll be finished
    with optics in 12 hours.

    About the triggers: When the elastic peak is on HAPPEX detector
    keep a 1:1 ratio of T1/T2 (and T3/T4). When the elastic peak is
    off the HAPPEX detector T2 and T4 will drop dramatically. In this
    case make up the difference with scint. trigger T1,T3 to keep DAQ
    rate at least 1 kHz.

    FIGURE 1