[Halld-pid-upgrade] DIRC bar box darkening plan

[Wenliang Li]

Dear all,

As soon as the run period finishes, we must start working on the 
darkening of the bar box to ensure successful full DIRC 
commissioning/operation in the fall.

With input from Justin, Mark and Tim, I have drafted the bar box 
darkening procedure on the DIRC wiki:

https://halldweb1.jlab.org/wiki/index.php/Bar_box_darkening_procedure

Any feedback or comment is greatly appreciated.

Many thanks

Bill