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    User name R.M./B.Craver

    Log entry time 12:12:59 on February25,2006

    Entry number 163823

    This entry is a followup to: 163813

    keyword=ideas to fix bad7 problems

    There is evidence chamber 1 causes the problem since we only
    changed its thresholds, and a high threshold (9) greatly reduced
    the noise rate which paralyzes TDC chips. So.... the ideas to
    fix this problem:
    1. Raise thresholds on chamber 1. And raise HV to verify the
    problem (bad7's) stays gone.
    2. Chamber 1 is unique in that it has new preamp cards. One might
    imagine putting back the old cards.

    In any case the hope is to reduce the bad7 rate with cosmics to
    zero, then perhaps further fine tuning of threshold/HV during beam.
    It is not obvious that TDC 1877 would not have the same problem ...
    we know that low thresholds on HRS cause these to be "paralyzed",
    so replacing TDC models is not sure to cure this. Perhaps better
    to work on the noise.