RE: Abundance of 727 KeV Line in Bi-212

[Arvic Harms <Arvic.Harms@npl.co.uk>]

Dear Leo,



You may also try:



S.A. Woods, D.K. Tyler, M.J. Woods, (2001). Nuclear data used in the

analysis of thorium in the workplace. Radiation Protection Dosimetry 97,

133-136.



Regards,



Arvic Harms



Dr Arvic Harms

Centre for Acoustics and Ionising Radiation

National Physical Laboratory

Queens Road

Teddington TW11 0LW

Middlesex

United Kingdom



E-mail: arvic.harms@npl.co.uk 

Tel ++44 20 8943 8512

Fax ++44 20 8614 0488 



> -----Original Message-----

> From: Leo M. Lowe [mailto:llowe@senes.ca]

> Sent: 28 July 2003 17:11

> To: radsafe@list.vanderbilt.edu

> Subject: Abundance of 727 KeV Line in Bi-212

> 

> 

> Hello,

> 

> In gamma spectroscopy analysis of samples containing natural thorium 

> (Th-232), almost certainly in radioactive equilibrium, the 

> concentration of 

> Bi-212 was much lower than expected (i.e. about 60% of the Th-232 

> concentration).  The Bi-212 concentration was based on an 

> abundance of 

> 11.8% (e.g. as given in ICRP 38) for the 727 KeV line.  

> However, if the 7% 

> abundance for this line as given in the Radiological Health 

> Handbook were 

> used, the Bi-212 concentration would be much closer to the 

> equilibrium 

> concentration (i.e. 7/11.8 = approx. 60%)

> 

> A similar ratio (between ICRP 38 and the Radiological Health 

> Handbook) was 

> also found for the 1.62 MeV line, with reported abundances of 

> 2.75% and 

> 1.8%, respectively (i.e. 1.8/2.75 = approx 65%).

> 

> What are the "accepted" abundances for the Bi-212 727 KeV and 

> 1.62MeV  lines?  Has anyone else had this problem?

> 

> If more appropriate, please feel free to respond to me 

> directly.  (I get 

> Radsafe via Digest mode i.e. only once per day.)

> 

> Thanks.

> Leo M. Lowe, Ph.D., P.Phys.

> Principal, Senior Health and

> Environmental Physicist

> 

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