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    User name R. Michaels

    Log entry time 13:29:31 on July 4,2010

    Entry number 330007

    keyword=Trigger 6 coincidence time spectrum

    This is already old news I guess, but I didn't see a plot yet
    so here it is: the coincidence time spectrum for Trigger 6 (fig 1).

    T6 = triple coinc of L-HRS scint + R-HRS scint + R-HRS gas Cerenk

    The self timing peak on the left side makes sense in terms of a
    simple model (fig 2) for the coinc circuit and the TDC. Normally
    the R-HRS Cerenk makes the trigger timing. This produces the
    TDC stop. Meanwhile the TDC start in this picture comes from T1
    (L-HRS Scint trigger). But if T1 slides late (random coinc) it
    eventually makes the trigger timing. Later times corresponds
    to smaller values in the TDC because it's a common-stop TDC.

    Note, the cut here is D.evtype==6. If you just cut on evtypebits
    you'll get a second self-timing peak from T1's that survive prescaling
    apparently because T1 arrives earlier than T6 at the trigger supervisor.

    The width of the randoms is about 115 units = 57 nsec (about right).
    I don't know if the rates make sense, but I think Bogdan said they
    do.

    I'd still like to make a check: the true coinc peak should disappear with
    a simple pulser test. But this looks pretty encouraging so far.


    FIGURE 1

    FIGURE 2