GM Response (formerly Respect)

["Kent N. Lambert" <lambert@auhs.edu>]

My sources indicate that C-14 has an Emax of 0.156 MeV and 
Eavg of 0.049 MeV  compared to S-35 with an Emax of 0.167 MeV 
and Eavg of 0.048 MeV.  So, can anyone answer why a Ludlum 
Model 3 with a pancake probe (or any other ratemeter with a 
pancake probe) would be "good" for C-14 but not S-35?  I would 
think that an instrument that measures C-14 at 5 - 12% efficiency 
would measure S-35 as similar efficiency.

BTW, a year or so ago, Wes Dunn posted a table of typical 
efficiencies of GM detectors for various isotopes.  It might be worth 
checking the RADSAFE Archives for this info.


Kent Lambert
lambert@auhs.edu

Peter Skeels wrote:

A Ludlum Model 3 with a pancake probe is a decent instrument for 
medium to high energy betas.  It has an average efficiency of 5% 
for C-14 and 15 to 20% for P-32 and Si-32.  S-35 is only detectable 
in large   quantities, so I wouldn't use it for self surveys after jobs.  


lambert@auhs.edu
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