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    User name brads

    Log entry time 04:34:11 on March 01, 2009

    Entry number 263979

    This entry is a followup to: 263956

    Followups:

    keyword=Added PSh discriminator to the T6 trigger

    Kalyan and I added 27 4ns cables between the PSh discriminator and the P758 logic unit that can make the coincidence between the PSh and the Shower. Those units were switched from OR to AND mode. This should significantly improve our pion/background rejection now that the total sums are fixed.

    The Sh signal was found to lead the PSh by 20ns at the AND. We explicitly measured several of the overlaps and found the 20ns offset to be extremely consistent. This means that the T6 trigger will now be timed off the PSh and will come 20ns later then it used to. (Both the Sh and PSh signals were 150ns wide coming out of the discriminator.)

    This will have the following consequences: 

    1. The ADC gates will come 20ns later then they used to.  This should
   be fine, but must be confirmed with the data.

2. The TDC stops all come 20ns later then they used to.  This will impact
   the MWDC t0 timing and will show up in any coincidence peaks. Offsets
   in the database will need to be added.


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