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    User name R. Michaels

    Log entry time 16:38:31 on October 02, 2009

    Entry number 292766

    keyword=re: recent helicity errors and synch mon problems

    If we have helicity errors and loss of synch which are due to hardware
    this is a disaster. However, I think the recent episodes may be
    explained by the following history.

    1. Errors made in db for HapNoQweak (fixed by Rupesh today)
    2. ROC31 crash --> use HapNoQweak --> apparent helicity errors (due to 1)
    3. Last night around 11 pm shift crew reacted to 1,2 by erroneously
    changing the helicity control board. This causes real helicity errors.
    4. Reboot injector crates, run happex config. Saw errors due to 3.
    5. Restored helicity control board. All was well on owl shift.

    Today the episode 1,2 was repeated.

    Also the apparent (false) synch loss appears to have been due to 1.
    After Rupesh fixed the db, the re-prompted runs had good synch.

    It should be checked that the synch signal is truly random.
    (As far as I can tell it is, but Luis may analyze some data.)
    This means a loss of synch shows up as a scatter plot with
    no correlation. If the dac12 was a ramping function we may
    be off by 1 event, for example, and it would be hard to tell.


    A copy of this log entry has been emailed to: paschke,silwal,mercado,zhaobo,mcnulty