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    User name paschke

    Log entry time 15:32:16 on June19,2004

    Entry number 126328

    keyword=PITA scan Run 2283, new PC voltages, IHWP IN

    For IHWP insertion (the first one since the spot move) I did a quick
    PITA scan.  Well, I did two, but there was no beam for all but
    one point in the first one (Run 2282, which is just junk).
    Dithering OFF, Charge Feedback OFF. IA cell to 5V.
    *** Moved RHWP to 6500 ***
    I put the PC voltages to the PC voltages which I _think_ represent
    the best circular polarization from the PC (I had trouble figuring
    out from previous log entries if this was correct).
    Run 2283.
     Delta    Pos    Neg   
      300    8.837   1.752 
      200    7.170   3.419
      100    5.504   5.085
        0    3.837   6.752
     -100    2.170   8.419
    The slope was 13.24 ppm/Volt, and the offset at 0V was 65 ppm.  From
    this, I set new PC voltages:
    For IHWP=IN, RHWP=6500  => PC Pos = 3.755, PC Neg = 6.834
    To back out of the calibration, I turned feedback and dithering
    back on.  Early results from Run 2284 suggest the IA cell is working
    harder than it should, so I need to modify the PC voltages again after
    this run.

    FIGURE 1