[ RadSafe ] Bismuth-212 and 727-keV gammas

[HHedge at GeoSyntec.com]

Dear Mike,

If the Thorium series activity is high in the samples you could be including a minor Ac-228 gamma line at 726.863 (15) keV, yield 0.62 (8) % in the reported activity of Bi-212. This data was taken from NuDat2 (http://www.nndc.bnl.gov/nudat2/indx_dec.jsp). It lists the Bi-212 peak as 727.330 (9) keV, yield 6.67 (9) %.

Regards,
Harold Hedge

Harold Hedge
Laboratory Manager
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______________________________________________ 
Date: Wed, 6 Oct 2010 16:30:40 +0100
From: "Arvic Harms" <Arvic.Harms at npl.co.uk>
Subject: Re: [ RadSafe ] Bismuth-212 and 727-keV gammas
To: "The International Radiation Protection (Health Physics) Mailing
	List"	<radsafe at health.phys.iit.edu>
Message-ID:
	<A77B33D816BA6B4DB6BDA65A08DF8B99027C7701 at exchsvr2.npl.ad.local>
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Dear Mike,

Please check out page 4 and 5 of

http://www.nucleide.org/DDEP_WG/Nuclides/Bi-212_com.pdf 

The numbers range from 6.3% to 7.6% (nine nuclear data evaluations
between 1960 and 1992). 

The DDEP recommended value is 6.74(12)%.

Kind regards,

Arvic Harms

Dr Arvic Harms
National Physical Laboratory
Hampton Road
Teddington TW11 0LW
Middlesex
United Kingdom
E-mail: arvic.harms at npl.co.uk 

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of McNaughton,
Michael
Sent: 06 October 2010 15:25
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
505-667-6130
mcnaught at lanl.gov