[Halld-tagger] first results on fiber light yields

[Richard Jones]

Dear colleagues,

We are working to obtain light yields for the first article fiber bundle
that was produced for the tagger microscope some time back.  We have run
into a problem trying to interpret what we see coming from the FADC250
module that is installed in the data acquisition crate we are using for
fiber QA tests.  Please see the plots on the wiki page linked below that
illustrate the problem we are seeing.

https://halldweb1.jlab.org/wiki/index.php/Tagger_Microscope#Light_yield_tests

When we look at the signals on the scope, we see one set of amplitude
ratios that clearly reveal the differences in light yield resulting from
different lengths of the fibers that are covered in reflective paint.  The
results from the FADC are much less distinguished, and disagree in the
ratios of pulse heights.  Comments or suggestions as to what we are doing
wrong would be appreciated.

-Richard Jones
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