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    User name paschke

    Log entry time 14:40:58 on October 07, 2009

    Entry number 293672

    keyword=Compton: Limit switch on electron detector adjusted

    The strike plate for the Compton electron detector motion limit switch was moved in a brief access.

    The ruling marks on the vertical reference rod ended an inch or more about the location of the strike plate, and the geometry did not lend itself to precise measurement with available tools. The old position (on top of the strike plate) was marked with a sharpie for reference for this change. The two hex screws were loosened and the strike plate moved down and then securely reattached. The change was measured to be approximately 0.1 inches (~2.5mm). This should put the electron detector strip 1 as close as 6.5mm to the primary beam (with the present beam steering) with a motion setpoint at -2.5mm or so.

    After leaving the hall, the electron detector was moved down to a setpoint of -4, to verify that the strike plate (visible on the camera) was not disturbed (this required a motion mechanism reboot as well). The epics readback on position was "in beam" and the strike plate appeared to not be moved after the edet was put back in its garage. At some future access, this strike plate should be briefly inspected again.

    The electron detector was returned to the garage and motion disabled before returning beam.

    A copy of this log entry has been emailed to: nanda@jlab.org, camsonne@jlab.org, rom@jlab.org, dwang@jlab.org, friend@jlab.org, mcnulty@jlab.org, dalton@jlab.org, segal@jlab.org