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    User name Katich

    Log entry time 11:01:53 on April29,2009

    Entry number 269706

    This entry is a followup to: 269640

    keyword=Re: Lumi Problems

    Sorry for such a late past - its still early here in Denver.

    This is in response to entry 269640.

    First - I'm not sure if it's a typo, but the above entry says "...tried to increase the high voltage in the first signal..."
    If this is really the case, it is only making saturation worse. The HV should be REDUCED when saturation occurs.
    The lumi HVs CAN be modified during a run - since the data is worthless when saturated anyway, there is no harm in fixing them. However, it is good practice to:
    1. only change the saturated channels
    2. make sure you are doing this either between runs, or finish the HV adjustment within the run you started working in (Rather than having screwy HVs for multiple runs)
    3. HALOG the change, and include the run numbers (LHRS, RHRS, HAPPEX) during which you were playing with the HVs

    I've tried to fix the HVs from here, but the connection is PAINFULLY slow. Xiaoyan agreed earlier in the week to be on call to fix these, and already fixed them once. She should be able to repair the saturated lumis. Also, in case she cannot be contacted, the expert on shift can follow the instructions here:
    http://compton.physics.wm.edu/~joe/upload/lumiExpert.html

    As a last resort, Bob Michaels and Bryan Moffit are the true experts on this stuff. But between Xiaoyan on call and the experts in the back room, I doubt contacting them should be necessary.