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    User name R. Michaels

    Log entry time 15:35:04 on December30,2003

    Entry number 115188


    keyword=trigger modifications

    The following modifications have been made to the trigger.
    The online doc's will be updated ASAP.

    1. Triggers T2, T4 defined.
    .... T2 = 2/3 from among S1,S2,gasC
    .... T4 = 2/3 from among S1,S2,S0 (both PMTs of S0 required)

    2. Triggers T6, T7 defined.
    .... T6 = T3 .and. A2 .and. .NOT. A1
    .... T7 = T6 .and. T1

    The timing/logic of T6 :

    ----------***----------- T3 (22 nsec wide)
    --------*******--------- A2 (51 nsec wide, 17 nsec earlier than T3)
    -----***************---- A1 (114 nsec wide, 45 ns earlier T3)

    A1 and A2 are logical pulses formed from the summed PMT signal
    above 30 mV threshold. Fine tune of gain may not be done (?)
    T3 and A2 must overlap. A1 provides a veto at P/S 764 logic unit.
    Timing of T6 determined by T3.
    Timing of T7 determined by T1.

    3. Timing at trigger supervisor: T5 and T7 overlap and
    come approx 40 nsec before T1,T2,T3,T4,T6. Due to non-trivial
    correlations (neither 1.0 nor 0.0) the online deadtime calculation
    in datamon needs upgrade. (Offline, no problem).

    4. To put S0 into MLU it was necessary to move the PMT
    signals from CAMAC crate 1, slot 2 to crate 2 slot 7.
    This uses the so-called "gas Cerenkov" lines. The TDC signals
    moved to fastbus roc 3 slot 3 chan 48-63. ADC remains same
    as during GDH. S0 detmap to be updated. Within the group of 16:
    S0A in 13th input
    S0B in 14th input
    A1-or in 15th input
    A2-or in 16th input

    5. Misc issues:
    a) S0, A1-or, A2-or labels put in scaler map.
    b) T6,T7 plugged into norm. scalers 17th, 18th channels.
    c) Helicity gated scalers on L-arm fixed.
    d) All scints plugged into scalers now.
    e) Gating of scalers tied to trigger supervisor as should be.
    f) No careful alignment of S1 timing yet.