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    User name R. Michaels

    Log entry time 10:05:35 on June 5,2007

    Entry number 204336

    This entry is a followup to: 204333

    keyword=more on BCM discrepancies

    This is a followup on my post 204333. See fig 1 for run 4055.
    What is plotted is BCM counts versus time (seconds) for upstream
    and downstream current monitors with three gain settings.

    As I said, the x10 BCM rolls over (32nd bit = sign). This is
    not a problem. It might also be saturated as Alex said.

    The x3 upstream BCM has a problem. Notice that it does not climb
    versus time like the others, i.e. it does not see the beam trips.
    What's more, it is THREE ORDERS OF MAGNITUDE lower than d3 or
    any other BCM counter. Therefore whatever is plugged into this
    scaler channel is NOT a BCM. Probably it's a pedestal from the V-to-F
    and that's why the charge appears to be close to zero on u3.
    I guess we should check the cabling, but it's also possible
    something is broken for u3. Note, the left HRS and right
    HRS scalers agree that u3 is bad.

    Bottom line: The halog entries see "one half" current for x3
    because it averages u3 and d3, where u3 = zero.
    Further, the x10 seems negative because of rollover.


    FIGURE 1