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    User name Armstrong

    Log entry time 09:17:53 on November 25,2002

    Entry number 2549

    This entry is a followup to: 2524

    keyword=new RHWP scan

    After we found that the Rotating half wave plate scan did not have a
    zero-crossing, I suggested we check the PZT values... find that the PZT Y
    voltage was still at 9 V (the nominal null point is 5 V). This is a remnant
    of the injector studies of a few nights ago. Possibly this is why, i.e.
    the position-charge coupling has pushed us to a point where the half-wave
    plate can't cross zero.

    So, we will scan around where we think one crossing is expected.
    Jianglai will post results of the "full" scan that was just done.
    We are running at 10 µA.


    
 Run       RHWP   
    
14612       7500
    
14613       6750  (junk, no beam)
    
14614       6750
    
14615       7200   (beam off for part of run, so let it go longer)


    Merde... MCC calls. The machine development is starting
    now (9:00 PM), not the previously advertised 10:00 PM... Beam is off.
    However, MCC says they expect beam back in two hours (11:00 PM).

    Meanwhile, we find that the zero-crossing should be at 6783 (135.7°).
    We should set it to this when beam comes back...