[ RadSafe ] Alpha to Beta Ratio Source Indication

Brennan, Mike (DOH) Mike.Brennan at DOH.WA.GOV
Tue May 29 11:44:19 CDT 2007

I can't think of a reason to believe that such a ratio exists.  There
are just too many factor.  For example, if you run a air sampler
collecting particulate on a filter, you will wind up with a lot of radon
daughter products on the filter.  When you first take the filter off the
sampler there will be a particular ratio of the various isotopes in the
decay chain (plus possibly other, unrelated isotopes from other
sources).  Some of the isotopes in the chain decay via alpha, some via
beta.  Over the next several hours the isotopes on the filter will
decay, total activity will decrease noticeably, and the ratio of alpha
to beta decays will change dramatically.  

Now, if in addition to a ratio you also could compare the results to
previously collected background results for the same media in the same
environment, you might well be able to say something, but I suspect that
it would mostly be a confirmation of what you already suspected. 

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Goff, Tom
Sent: Tuesday, May 29, 2007 5:42 AM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Alpha to Beta Ratio Source Indication

Does anyone know of a basis for determining if the source of
radioactivity on a smear or air sample is natural, fission product or
transuranic based on the alpha to beta ratio.  

For example, if the ratio is greater than 3 then the source could be
Actinide; it the ratio is less than 0.5, the source could be fission
product; if the ratio is between then natural radioactivity is

Does anyone know of a reference for these ratios?

Tom Goff
WIPP Radiological Services
505 234-8861
fax 505 234-6062
<mailto:Tom.Goff at WIPP.ws>
P.O. Box 2078
Carlsbad, New Mexico 88221
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