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    User name Armstrong

    Log entry time 12:56:42 on June10,2001

    Entry number 62802

    This entry is a followup to: 62791

    keyword=more on charge asym


    Latest run (518/20518/718) now has a positive charge asymmetry:
    apar (run 718): +110 ppm
    qasy (run 518): + 266 ppm (some outliers)
    qasy (run 20518) + 165 ppm

    Conclusion: The charge feedback appears to be working - Bob Michaels
    tells me he has also seen (by spying on EPICS data) that the relevant
    epics variable (see entry 62754) for the 1/2 wave plate is indeed changing
    now.

    Bob also tells me that I was wrong in my hypothesis that the scaler events
    are not gated by the Pairty DAQ - in fact they are, the events that one
    sees when one starts the sepctrometer DAQs before the parity DAQ starts
    are epics events and scaler events, but these scaler events will be empty,
    the actual scaler values will be zero - so this doesn't explain why the two
    spectrometer DAQs can give different values for the charge asymmetry.

    I will "timestamp" a somewhat smaller value (+75 ppm) since I think
    that we overshot -> perhaps the slope is no longer the same as it was?

    The "Helicity Correlated Feedback Controls" GUI doesn't read back
    a value at the moment for ppm/step - but I recall it was explained to me
    that this part of the GUI is not yet functional.