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    User name Armstrong

    Log entry time 11:16:16 on November 25, 2009

    Entry number 302507

    keyword=Prescale adjustment

    Bob Michaels calls: he suggests that we try increasing prescale factors to reduce the deadtime while the FADC is being readout.

    After a couple of junk runs (problems resetting the pre-scale factors and a CODA crash), we have adjusted the prescales as follows,
    for runs 5298 (right arm) and 25755(left arm) while run 14207 (HAPPEx) continues:

    Left arm     Right arm 

    ps1  4000   1200
ps2  2800    800 
ps3     2     60
ps4     2      4
ps5    10     80
ps6  2800     80
ps7 40000   8000
ps8   200    200
    The effect is that the deadtime at 110 µA goes from 80-90% down to 30-40% for left arm and to 50% for right arm.
    So we have improved, but maybe not gone as far as one might like. Of course, we should remember to undo these changes if we go back to not reading out the FADC.