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    User name brads

    Log entry time 12:28:46 on February 17, 2009

    Entry number 261623

    keyword=BB cerenkov PMTs 1--8, 11--18 split to both 1881 and FADC

    The signals for PMTs 1--8, 11--18 (upper-most 16 PMTs) were split using a 50 ohm passive splitter. One copy goes to the 1881 as before, one copy runs to the FADC.

    NOTE: This means the amplitude in the 1881 will be 1/2 of what it was for the 16 affected PMTs only. PMTs 9,10,19,20 will have the same amplitude as before. This can be trivially accounted for in the BB.cer database, but will need to be treated by hand for the DBB.BBcer* variables.

    Another side-effect of the split is that the signals reach the ADC 8ns later than before (relative to the gate). This should have no effect.

    The FADC channel map is:

       Channels 0--7:  PMTs  1--8
       Channels 8--15: PMTs 11--18

    A copy of this log entry has been emailed to: posik,flay,yqiang,xqian