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    User name Jin

    Log entry time 22:44:07 on November 03, 2008

    Entry number 246529

    This entry is a followup to: 246527

    keyword=Re: BCM gated scaler data are non-zero, but look bogus too

    That's because both Target Up and Target Down channel is Logical 1 now.

    The reason I set the signal to this state, rather than normal spin
    up/down state is:

    1. It enable all 4 scalar to counting. 2 of them gated by same helicity
    signal should count same. In this way, we could have a double check.

    2. The signal is set by hot wiring the electronics. By setting to a
    unphysical state, it will remind us to remove the hot wires before
    production.

    It have to be hot wired because, the spin logic electronics is designed
    to be fail safe : if there is a failed flip during the run, then it
    will send out "unknown spin state". Base on current scalar setup, it
    will disable all 4 gated scalars. EPR, which is not supposed to be done
    during normal runs, will send "failed flips". That's why gated scalars
    are disabled after EPR.