Email from Dave:

Date: Thu, 30 Sep 2004 11:35:18 -0400 (EDT)
From: Dave Mack 
To: Mark Pitt 
Cc: Roger Carlini , Jim Birchall ,
     Juliette Mammei , Klaus Grimm ,
     Neven Simicevic , Greg Smith ,
     Allena Opper , Tony Forest ,
     Norman Morgan , Mike Finn ,
     David Armstrong , Yongguang Liang ,
     Shelley Page ,
     Richard Jones 
Subject: Re: Qweak working group - today's meeting


	Mark et al,

	I have to take the next generation to swim team at this time, so I
won't be part of today's call. 

	Can someone remind me what criteria GEANT3 is using to plot the
secondary photons generated in the shielding/collimators? 

1) we're not interested in photons which don't interact in the quartz.

2) we're not interested in photons with energies below about 0.3 MeV due
to our Cerenkov threshold (in Babar tests, Spectrosil 2000 had 
negligibly small scintillation)

3) we're probably not even interested in photons energies below several
MeV, but now I'm going out on a limb. Since the Compton angular
distribution and quartz stopping power are involved, only a full
simulation can tell us if these events have significant weight compared to
the 50-100 pe's generated by each elastic electrons. 

	regards,

	Dave