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    User name R.Michaels/Alex

    Log entry time 17:19:27 on July 6,2007

    Entry number 207829

    keyword=trigger work

    Makis wants to reach a momentum of 765 MeV/c for He-4 which requires
    a delay diff between HRS of 340 nsec, an increase of 20 nsec compared
    to the previous limit. The trigger setup GUI has new limit 345 nsec.

    Alex and I investigated if this is possible. We found that we have
    enough headroom (barely!) and didn't touch anything, but checked
    things on the scope, in particular we checked coincidence overlap
    and both HRS retiming. The reason it works is that we don't have
    to change the L-arm delay. This makes the coinc. overlap more
    "marginal" (and there is hardly any room left, remember signals
    must overlap by 5 nsec to make a coinc.) but didn't change the
    delicate L-arm RT. If you want more range in beta, you will simply
    have to add more analog delay on the L-arm.

    There are three implications due to the limit on digital delays.
    They could probably be alleviated if more range in momentum were
    required, but they are minor at this point, and we did nothing.
    The effects occur for lowest beta. These are:

    1. R-arm RT became tighter (down to 25 nsec).

    2. T2 slides relative to other triggers by up to 12 nsec.

    3. R-arm coinc time measurement "TCR" will slide in the TDC.
    Alex says it will remain in the TDC's range so it's ok.
    Note, the L-arm (redundant) TCL does not slide.