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    User name brads

    Log entry time 18:14:29 on October 31, 2009

    Entry number 297039

    This entry is a followup to: 296908


    keyword=Helicity, MPS signal timing update

    Riad gave me a call Friday afternoon with a little information on the MPS/Helicity timing. Here's what I gathered from the conversation:

    He made a comment that the PVDIS group had mentioned the 25us gap between the MPS and HEL signal "a couple of months ago", but it wasn't clear to me if anything was changed in the injector (I don't think so). There are a several halog entries mentioning MPS in the Halog during September, but no mention of a delay shift or problem with the HEL timing.

    Riad doesn't think their system is even capable of producing a 25us delay between those signals. He suspects that there may be some flaky component downstream of the injector: ie. optical<->NIM convertor board. Something we should watch for...

    A new Helicity board is being installed this coming Monday. The planned 'correct' timing has the HEL transition lag the MPS by 1us. The MPS window will remain 500us. If it ever shifts from these values, we should check our signals in the counting house, then notifiy the injector group if the change persists.

    We need to check the timing in our systems after Riad lets me know the board swap is complete. Halls B and C will also check the timing they see.

    A copy of this log entry has been emailed to: gen@jlab.org, brads@jlab.org, glamazdi@jlab.org, rom@jlab.org