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    User name R. Michaels

    Log entry time 12:19:44 on February26,2001

    Entry number 57004

    Followups:

    keyword=fixed a few scaler problems

    During the access for dipole polarity, I fixed the following problems with scalers:

    1. The 10Hz pulser counted in the 22nd channel of the normalization
    scaler was double counting. The signal was observed to have a ringing tail.
    By using an isolated output from an upstream source instead of using an
    NIM/ECL to fanout the ringing went away, see 10Hz now.

    2. The halog reports "deadtime from gated scalers". The deadtime is computed
    from a ratio of the following two: a) signal and b) (signal.AND.not-busy)
    where "not-busy" is the inverted busy signal from CODA trigger supervisor, and
    signal can be anything. We use two signals for this: charge-Q10 and the
    1024 Hz clock. The AND with not-busy goes into resp. chan 17 and 18 of
    the normalization scalers. There were two problems, which I fixed:

    2a) The Q10 used to AND with not-busy was U10. But the halog end-run
    script runend.tcl assumed it was D10. Since there is an offset in frequency,
    this lead to errors in end-run entries which were very noticable for cosmics
    runs where it computed a negative deadtime. Fix: changed runend.tcl to use U10.
    No big deal since the U10 results look good.

    2b) The deadtime for clock.and.not-busy was hopelessly wrong because the
    coincidence module was set to make an output with only requiring input #1.
    Fix: set coinc module correctly (requires both inputs).

    I think problem 2a existed since cabling changes in Jan (and is not really
    a problem anyway) but 2b probably existed forever.