[Halld-pid-upgrade] DIRC south box Mirror reflectivity report

[Wenliang Li]

Dear all,

Please see the report on the DRIC south box mirror reflectivity report 
in the docDB:

https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4127

If we summarize the finding in one sentence: the white unremovable trail 
mark reduces the mirror reflectivity by as much as a factor 5 (less than 
20% reflectivity).

Many thanks

Bill