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    User name paschke

    Log entry time 17:05:23 on July16,2003

    Entry number 104075

    keyword=Hall C beam effect on Hall A beam


    This afternoon G0 performed parasitic tests with source elements directly effecting
    only the Hall C beam (IA/PZT scans). As agreed, we monitored the effects in
    Hall A. It appears that a very large fraction of the effect seen on the Hall C beam
    was seen on the Hall A beam.

    Figure 1 is from parity DAQ run 3305, between 14:00-15:00 this afternoon. It is
    unclear exactly which portion of the G0 studies this represents: probably one of the
    PZT scans. The three evident values of charge asymmetry represent the
    two extreme and middle setpoint for the PZT setpoint. The apparent slope is
    approx. 675 ppm/Volt.

    G0 records a charge asymmetry slope of 740 ppm/Volt for the PZT scan. If fig. 1
    shows the PZT -X scan (and not PZT-Y, for which we don't yet have results
    from G0) this would suggest that the effect on the Hall A beam is 90% of the effect
    on the Hall C beam!

    Hall A was running near 2-3 uA, and Hall C at 90 uA. Was 90% of the
    Hall A beam coming as bleedthrough from Hall C? If not, other effects (like
    cathode loading?) may need to be considered.

    Also: the magnitude of charge asymmetry I quote here is sensitive to the BCM
    pedestal, which has not yet been calibrated. Hopefully we can use the lumi (or the
    BCM calibration procedure to be performed in the next couple of days?) to check
    this parameter.



    FIGURE 1