Re: More Questions on Alpha Emitters

[Ninni Jacob <njacob@gsosun1.gso.uri.edu>]

On Thu, 27 Oct 1994, USHINO, TOSH wrote:

>      I'm looking for a simple, quick and relatively inexpensive method to 
>      do alpha spectrum analysis on air filters.  The goal of the analysis 
>      is to determine quickly if the detected alpha activity on an air 
>      sample filter is due to natural radon daughter products, or if it is 
>      due to other isotopes I have to worry about.  Our current method is to 
>      evaluate them by alpha/beta ratio, but the ratio is affected by the 
>      age of the sample, sampling time and dust-loading on the filter.
>      
Have you tried recounting them after 35 minutes?
The effective half life of radon daughters is about 35 minutes, so the count
should be half if the activity is due to radon daughters only.

Ninni Jacob
Radiation Safety Officer
University of Rhode Island