BG simulation section for the TDR

[Alexander Somov <somov@jlab.org>]

Hello all,

I put a draft of the short description of the collimator cave
background simulation for the TDR

http://www.jlab.org/~somov/tagger_review/bg_section/


I gonna add a paragraph, might be one more plot, desribing
PS shielding there (I'm working on it now).

Cheers,
       Sascha