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    User name Sirish

    Log entry time 17:30:04 on November13,2007

    Entry number 214337

    Followups:

    keyword=Compton Back Online

    Compton photon DAQ problem is fixed. Replacing a cable on the trigger line seems to do the trick.

    For running the background check the guidelines are as follows:

    1. Photon detector HV=-1500 V (Beamline crate, slot 11 chan 1)
    threshold=10 mv
    ---- DO NOT CHANGE THESE VALUES ----

    2. < 10kHz/uA in photon counting rate is good beam

    3. If rate exceed 10 kHz in a sustained manner action has to be taken.

    a) if rates are 10 - 100 kHz request MCC to reduce compton photon
    rate, ususally via "dogleg pathlength" corrections. This is
    generally non-intrusive to the Halls.

    b) if rates are > 100 kHz, the injector tune is likely to be bad.
    Request MCC to check injector. This is intrusive and takes a
    while.

    c) if rate > 1 MHz turn off photon detector HV.

    4. After every machine retune, e.g. Energy Change, First go straight
    bypassing Compton Chicane. Check for momentum spread < 5E-5 in the
    SLI and visually check for a clean symmetric beam on the target
    OTR. If these check out ok, turn on the Chicane to monitor photon
    rate.