Threshold and Sampling Fraction

[Matthew Shepherd <mashephe@indiana.edu>]

Hi Richard and Zisis,

It seems we can already take Blake's parametrization for the sampling  
fraction and sampling fraction variance and code this up into GEANT  
to introduce the fluctuations.

The key remaining issue then is how do we set a realistic threshold  
for the MC?  We know from George that roughly 26 keV of energy in the  
fibers gives 1 PE.  So we need to understand what the SiPM readout is  
capable of separating from pedestal, correct?  Any thoughts on what  
this number is?

Of course this involves things such as electronics noise and maybe  
even the specifics of how the fADC processes event buffers to pick  
out signals.  As a starting point, I wonder if it is it possible for  
us to begin to make a reasonable estimate (in terms of "photo- 
electrons") what the fADC threshold is.

I'm not sure if we need a phone conference to do this or not -- maybe  
we should exchange some ideas on setting the threshold through email  
and see where we get.  Others on the halld-cal list may have ideas.

-Matt