[ RadSafe ] Bismuth-212 and 727-keV gammas

Bradshaw, Keith kzb Keith.Bradshaw at amec.com
Wed Oct 6 09:46:06 CDT 2010

Mike, we get consistent Th-232 decay series results using DDEP or LARA nuclear data.  In these, the 727keV Bi-212 gamma emission probability is 6.74%.



This is also the same in JEFF 3.1.  In passing I notice the Table of Isotopes value is 6.58%.


So that is not a million miles away either.  I've not seen a value of 12% in any of our data sources here.

Personal views only

Keith Bradshaw

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of McNaughton, Michael
Sent: Wednesday, October 06, 2010 3:25 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: [ RadSafe ] Bismuth-212 and 727-keV gammas

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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