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    User name R. Michaels

    Log entry time 00:27:26 on January17,2009

    Entry number 256409

    Followups:

    keyword=extra hits in Fastbus

    There are extra hits in fastbus on ROC3. Not sure about ROC4
    but it appears to be much less frequent there. The probability
    appears to be appoximately 7.6 % for ROC3. The pattern is that
    all slots in ROC3 get 1 extra hit. This was observed in some
    primitive codes which I used, but not in Podd because the flag
    VERBOSE=0 in THaCodaDecoder turned off this warning.

    The way the electronics works is that every L1A produces a gate.
    If the fastbus sees 2 gates then the 2nd hit is stored in the
    buffers of all modules (what we observe). If the 1st hit is
    the "correct" one, this MIGHT not be a problem. But it's an
    experiment with electronics which I wouldn't want to use beam
    time for.

    Why it's less frequent than the double-pulsing in scalers is
    perhaps due to the time interval between pulses. If they are
    too close the fastbus doesn't respond (deadtime), whereas scalers
    are much faster. This is a guess. Need to look on a scope.

    These extra hits may be related to some other anomolies observed
    recently in the data.