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    User name R. Michaels

    Log entry time 12:16:43 on December 16,1999

    Entry number 31228

    keyword=problem of T4 - can affect normalization

    I investigated trigger 4 which involves S0 to measure H-arm
    inefficiency. There is a problem here that many of the T4
    should actually be T3. If this is not corrected it can lead to
    a normalization error for the experiment. So far we have the
    following observations and ideas: 1) The fraction of T4 which
    are T3 varies with momentum, but looked clean for cosmics;
    2) The T4 have significantly different timing (50 nsec) than T3;
    3) I think this happens because the 2nd MLU which forms
    the majority logic is in transparent mode. S0 comes rather
    early, S-Ray late. The MLU gets confused when it sees an
    overlap of S0 and S1 with S-ray late; 4) The implication for now
    is to keep plenty of T4 (at least 50 Hz) so that analysis can correct;
    5) We may want to take access and delay S0 by ~30 nsec.

    Note, T1 and T2 (E-arm triggers) looks ok.