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    User name R. Michaels

    Log entry time 14:49:45 on April 8,1999

    Entry number 17445

    keyword=beam cross talk tests

    We got beam back. Now do the beam cross talk tests.
    First run with 30 microamps, run 4268, to see what is
    there. About 32000 channels in the detectors and
    35000 channels in the bcm's.
    Next steps:
    1. Close B and C slits. Leave A slit open.
    2. Turn off A laser. Leave B and C laser on.
    This will be run 4269 (hall A HAPPEX DAQ)
    Result bcm1 = -170, bcm2 = -314, det1=830, det2=80
    Next runs (some #'s skipped due to CODA crashing...)
    3. A laser off, B on, C off -- run 4271
    4 . A laser still off, B off, C on -- run 4273
    5. All lasers off (dummy check) -- run 4274
    Result of run 4274 -- bcm1 = -170, bcm2 = 314,
    det1 = 765, det2 = 15.
    Assuming run 4274 is a true pedestal run and that
    this does not drift, and comparing to run 4269, we
    conclude:
    1. bcm signals hardly differ with B,C lasers
    2. detector signals may differ. det1 diff is -65,
    det2 diff is -65. Note: signal went DOWN with
    all lasers off. Even so, 65 is a 0.2% effect.