[Rich] H12700 review

[Andrey Kim]

Dear collaborators,
Please find H12700-H8500 comparison review here: 
https://userweb.jlab.org/~kenjo/H12700report.pdf

"Short" summary: *H12700 is still better than H8500 due to the higher 
photocathode quantum efficiency.* The nearly uniform illumination of 
pixel shows that SPE spectrum is not as good as it was anticipated. It 
has more complicated structure than H8500. The structure was described 
using Pavel Degtiarenko's model, and using his model's fit results the 
collection efficiency was estimated for both MAPMT types. The H8500 
demonstrated higher collection efficiency than H12700 (unexpected and 
rather saddening behaviour). Fortunately, H12700 has higher photocathode 
quantum efficiency, and it was determinative factor in H12700 superiority.
Please note that separation of quantum and collection efficiencies is 
possible *within model framework only.* However, the *global efficiency 
(decisive criteria)* is model independent as it is the fraction of 
events with signal over pedestal's 5 sigma (assuming, of course, that 
light source is stable and constant).
Any comments, suggestions or corrections are welcome!
Thank you!

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