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    User name R. Michaels

    Log entry time 02:27:29 on February 28, 2006

    Entry number 164371

    This entry is a followup to: 164320

    Followups:

    keyword=Re: Qasy with GeN DAQ

    It occurs to me that a very wrong BCM calibration could lead to the spurious result of
    GeN DAQ charge asymmetry. I would suggest a current scan: perhaps w/o target, and
    10 minute runs with 0.5, 1, 2, 5, and 10 uA if possible. It would also help to do seperate
    runs with deliberately large Qasy, say 1000 ppm, and measure with all DAQs.

    The Qasy is probably small and well measured by HAPPEX DAQ, but establishing we can
    measure it with GeN DAQ is vital to prove the full chain of electronics + software is working.
    What's more it calibrates the sign of the asymmetry. If we cannot measure a 1000 ppm Qasy
    then we cannot meaure the physics asymmetry. The Qasy in scalers should be corroborated
    by a Qasy in events with runs long enough to get precision using deliberately large Qasy; this
    also helps establish deadtime and nonlinear corrections to the physics asymmetry.

    A copy of this log entry has been emailed to: bogdanw@jlab.org,cates@virginia.edu