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    User name Armstrong

    Log entry time 11:10:24 on June10,2001

    Entry number 62791

    This entry is a followup to: 62774

    Followups:

    keyword=Charge Asymmetry


    More on the charge asymmetry feedback:

    I notice that "qasy" results are not always consistent between Left and Right
    arms - why?
    Well, the scalers events are not gated by the parity DAQ, I believe,
    so that the two arms can sample different events since the two runs
    don't really start simultaneously.
    Also, the values we read from "qasy" are not fits to Gaussians, just mean
    and RMS of the distributions, so can be very sensitive to outliers -
    in particular the results of analysis of runs 20513 (-520 ppm) and 513
    (-250 ppm) are, based on the histograms, just an artifact of a few outliers
    in the Right arm (run 20513).
    However, Antonin has fixed the parity analysis ("apar"), and so I run
    it on on the most recent runs, and the results are much more stable:

    Charge asymmetries (all in ppm)

    Right and Left arm values from "qasy"; Parity value from "apar"


    Right arm Left Arm Parity
    ------- -------- -------
    Run # Run # Run #


    20515 -85 515 -95 715 -132 (after fix)
    20514 -185 514 -250 714 -320 (before fix)
    20513 -520 513 -250 713 -390
    20512 -360 512 -300 712 -430
    20511 -320 511 -330 711 -400

    The fix to the charge asym feedback was actually done near the end of
    run 20514, so one can believe it is starting to get smaller then already...

    I timestamp the new value of -132 ppm with error of 10 ppm, and
    we will see if this improves further....

    (D.S. Armstrong)