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    User name R. Michaels

    Log entry time 20:11:17 on October 4,1998

    Entry number 2340

    keyword=cause of DAQ slow-down

    I've been called a few times because the event rate dropped,
    and/or the deadtime was high. On these occassions the event
    size was also high. Normally it is about 0.8-0.9 kbytes per event,
    and if it becomes substantially bigger, the DAQ will obviously
    slow down. Look at the event size = differential kbytes/sec divided
    by rate. This is almost certainly NOT a CODA problem, but
    a detector noise problem. My guess is the VDCs are oscillating
    again. The experiment should isolate and analyze these big events
    to determine the cause. I wonder how well they reconstruct.

    Also re: the CODA crashes. You might try asking MCC to shut
    off beam before pressing End Run. If G. Heyes is right, this will
    make the probability to crash at start-of-next-run negligible.