[ RadSafe ] Bismuth-212 and 727-keV gammas

Peter Bossew Peter.Bossew at reflex.at
Wed Oct 6 14:24:37 CDT 2010


acc. to the Lund database the emission probability of the 727 line of
212Bi = 6.58%

In evaluating gamma spectra,don't forget interference by the nearby 726.9
line of 228Ac, 0.62%. If the Th series is in equilibrium (approx. the case
in common environmental samples), this adds about 10% to the 727 line of
A (very) small contribution may also come from the escape line of 1238 keV
of 214Bi. 
I suppose you did correct for BG ?


Peter Bossew
Bundesamt für Strahlenschutz (Federal Rad.prot. authority), Berlin

"The International Radiation Protection \(Health Physics\) Mailing List"
<radsafe at health.phys.iit.edu> schreibt:
>Dear RadSafers
>I have a problem with the gamma-spec results for bismuth-212. The
>reported concentrations for bismuth-212 are consistently higher than
>those for Pb-212, as well as for all the other nuclides in the
>thorium-232 decay chain. This is the case for several types of samples,
>collected over several years, and analyzed at several different
>analytical labs.
>I suspect the problem is with the emission probability (or "intensity")
>for the 727-keV gamma. Different publications list different numbers for
>the emission probability. The numbers range from about 6% to 12%. 
>I would like to discuss this problem with others who are interested. 
>Thanks, mike
>Mike McNaughton
>Los Alamos National Lab
>mcnaught at lanl.gov
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