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    User name Longwu Ou

    Log entry time 17:54:13 on July 07, 2014

    Entry number 1247

    keyword=Negative dead time for some runs

    From recent test we saw negative dead time for some runs. 
    
    Dead time calculated according to the formula (if only one trigger is 
    used):
    
    DT = 1 - ps*#Rec/#Scalar
    
    where #Rec is obtained by cutting on evtypebit and #Scalar is total 
    counts from scaler variable in the tree.
    
    For run 1620, 1624, we get negative dead time from this calculation.
    
    RUN NO.     Prescale factor             Dead time
    1620        ps7=2 other=0               -3.48%
    1624        ps7=2 other=0               -2.22%
    
    Trigger 7 was a pulser at about 2kHz in run 1620 and at about 100Hz in 
    run 1624 respectively.               
             
    


    A copy of this log entry has been emailed to: kalyan@jlab.org