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    User name paschke

    Log entry time 18:24:56 on February 8,2003

    Entry number 95418

    keyword=PZT scan aborted


    The promised PZT scan never materialized. A couple of problems were chased
    down, and I finally gave up when it was clear that configuration changes
    were going to delay completion of the scan for several hours.

    One small accomplishment: it was necessary to calibrate the IA cell to PZT-X(Y)
    ratio that would keep charge asymmetry small. This was done during parity runs
    1830-1831. I changed the feedback parameters so that I would feedback in
    1 minute intervals (instead of 2) to minimize the duration of any Aq offset. I started
    by making small excursions to estimate the IA vs. PZT slopes, and then used
    those rough estimates to control Aq during large PZT settings. The charge
    asymmetry was well-controlled by feedback during this entire procedure,
    and I never observed a 1-minute average larger than 150 ppm.

    The slopes I finally found were V(IA)/V(PZT-X) = 0.43, V(IA)/V(PZT-Y) = 0.11.
    These were measured with the HWP=OUT and RWP at 6200.

    I also found that bpm4a was hosed. The problem started during
    run 1819, about 7:30 this morning. I traced the problem to the ADC, but didn't
    diagnose and further. the bpm4a signals were swapped with bpm8 so that we
    could continue to use target bpm information. Probably the pedestal
    information needs to be updated for ADC8, but we'll worry about that another day.