• Main INDEX
  • Monthly INDEX
  • PREV
  • NEXT
    Make New Entry, Make Followup Entry

    User name R. Michaels

    Log entry time 12:10:56 on February 09, 2009

    Entry number 260010

    This entry is a followup to: 259993

    Followups:

    keyword=re: helicity

    Some observations by Vince, Bryan, Kalyan, and me:

    1. In 1-DAQ mode, BPM/raster data are out-of-synch between L-HRS
    and bigbite. This is a bad sign.

    2. helicity from TIR L-HRS in synch with bigbite, but ROC4 ADC helicity
    is out-of-synch. This is consistent with 1.

    3. Get "synch errors" from decoder (still suppressed by the
    official Podd version), relating to extra hits. The pattern mostly
    affects ROC3 apparently (few % of events).

    4. No such "synch errors" for 2-DAQ runs. Speculation is the L1A
    from bigbite, which looks somewhat distorted on a scope, is causing
    extra gates in fastbus. It may be necessary to change this cable
    or fix it's connectors. I remember we had a similar problem during
    Transversity and there's an halog by me about it; we swapped the
    small cable that goes to the TM module and the extra gates went away.

    5. Available synch counters (clocks, event counts, event type) look
    in-synch on the L-HRS fastbus; however, these are immune to extra gates.
    But it suggests nothing wrong with trigger supervisor interaction.

    Conclusion: Most likely, need to fix the L1A from bigbite. It won't
    matter for 2-DAQ mode, however.

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