[Halld-tagger] [EXTERNAL] notes from tagger working group meeting this morning

[Richard T. Jones]

Hello all,

We had a special meeting this morning at 10:00 devoted to a review of
everything we know regarding the degrading response of the tagger
microscope over the last few run periods. A new logbook entry has been
added containing a historical record of the photon yield and other
calibration constants for the TAGM which presents clear evidence of
significant loss of scintillation photon yields over the past 5 years, with
most of the loss occurring in the rows that saw the greatest flux of
electrons.

   - gain and photon yield history of the tagger microscope
   <https://logbooks.jlab.org/entry/4459304 >

Ideas to further investigate the exact reasons for the decrease, as well as
ideas for recovering and sustaining good performance during Phase 3 running
are still in process, with follow-up to happen in the next Photon Beam
working group mtg next week.

-Richard Jones
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