GX-doc 1045 on Light Guide Surfaces

[Matthew Shepherd <mashephe@indiana.edu>]

Dear colleagues,

I've just uploaded document 1045 to the portal.  This note documents  
work done by Sam Adams and Chris Cude on characterizing the  
transmission of the light guide prototypes.  It also provides a  
discussion of studies regarding mechanical coupling of light guides to  
blocks.  The net result is that we anticipate a net gain in photon  
collection efficiency of a factor of 2.3 over RadPhi.  The net change  
in the statistical term of the energy resolution depends on what  
fraction of that term is due to photostatistics.  Our estimates are  
that the statistical term in the energy resolution should be about  
5.7% / sqrt(E) for GlueX.

We are working on a stable technique and setup to do QA testing for  
light guides  -- I think one lesson we've all learned is not to trust  
our eyes.

-Matt