How do you determine 2000 dpm... Say for S-35. How do you measure this inside a Fuge? What efficency is used and how is it determined? How do labs determine if they are over 2000 dpm? Do they measure on contact or at some distance? Do the meters have various efficiencies for different nuclides? C-14 vs P-32! William A. Lorenzen Children"s Hospital lorenzen_w@a1.tch.harvard.edu