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    User name miham and moffit

    Log entry time 01:50:37 on April 23, 2009

    Entry number 267428

    Followups:

    keyword=The coincidence trigger and the BB re-timing problems

    During the controlled access (9pm - 11pm) Bryan and myself went down the
    hall to set up the coincidence triggers (T5 and T6) and the Big-Bite
    re-timing.

    Based on the EDTM signal and our calculations of the delay between the
    L-HRS and BB, we first applied some additional delay to the T1 (E-plane
    trigger ) and T2 (dE-plane trigger) triggers so that these to signals
    came in the middle of the T3 triggers (from the LHRS). Then we formed the
    coincidence triggers (T5 = T1 and T3) and (T6 = T2 and T3).

    However, when we checked the time difference between the L1A signal from
    the TS and the analog signal to the ADCs we realized that the gate for
    the ADC comes to late. This poses a serious problem, because if (at the
    current setting) we want a coincidence trigger we miss the ADC signal.

    On the other hand if we take some of the delay out from the T1 and T2, so
    that catch the analog signal to the ADC, than T3 comes to late and we can
    not form the coincidence triggers.

    We haven't figured out yet, what could be the best solution of this
    problem. The first option would be to find out if the T3 signal can come
    faster from the L-HRS. The other possible solution is to introduce some
    additional delay to the ADC-signals. For this we would need 96 60ns cables.

    In the end we have decided to set a simple trigger until the morning. We
    have taken away some delay off the T1 so that now(according to the EDTM
    calibration) T1 signal comes approx. 30ns before the T3 signal, which
    causes that the ADC gate opens fast enough for the ADC signal. Then we
    set the BB re-timing in a way that the gate for the ADCs is always timed
    of the T1. We left the T2 out of the re-timing, because we weren't able
    to set the delay for the T2 properly (ran out of time) and would mess out
    re-timing. Therefore should runs, that will be taken during the night
    have the T2 pre-scaled out.



    A copy of this log entry has been emailed to: moffit, miham