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    User name A. Camsonne

    Log entry time 14:57:01 on April 23, 2009

    Entry number 267551

    Followups:

    keyword=Ramping down HV for EDTM overlap check

    Not sure where to get the corresponding channels of S2m (the
    discriminator is far) and S1, so I decided to look at Or of S1 and or of
    S2 since they are easily available as NIM signal. I turned left HRS HV off
    Looking at the signals S1 arrives about 80 ns before the beginning the
    S2m, it seems they overlap a bit but it can be improved.
    There is one oddity is that on the or signals I see many S1 EDTM without
    corresponding S2m signal.
    I see one EDTM pulse for every S2m pulse though.
    I modified the edtmsetup script to add 75 ns of delau to S1 and the
    overlap is almost perfect.
    People might want to remove this change since it might mess up the way
    the timing is done with the EDTM.
    I checked at the coincidence module generating T3, the overlap is perfect
    there too since it is another output of the NIM/ECL module.
    Not sure from when the T3 dates from, but it seems the signal of or of S1
    and or of S2m have almost the same width might be worth shortening it and
    centering it to make sure S2m always define the timing of T3.
    Feel free to remove the delay I added to the edtmsetup script

    let DELAY1=$OFFSET+$DBETWEEN_ARMS+75 # added delay to have them overlap
    at NIM/ECL converte where the OR of S1 and S2m arrive

    Turning HV back on to check at real cosmics coincidence



    A copy of this log entry has been emailed to: rom@jlab.org,vasulk@jlab.org,moffit@jlab.org