Re: ?NVLAP category V C

[BFLOOD@SLAC.Stanford.EDU (Bob Flood)]

>My badge does not have filtration to distinguish the beta energies.  The
>badge is designed to handle both neutrons and photons as well, so three
>elements are filtered with Cu, Cd, and plastic.  A mylar window covers
>the sole thin beta-detecting chip.    

You don't give the density thickness of the filters for the other 3
elements, so I will assume they are thick enough to eliminate response even
to Sr/Y-90. If that is the case, you have a 1-element beta measurement
device. Algorithm corrections for beta energy dependence are possible only
if you know the energy characteristics of the beta spectrum incident on the
dosimeter. Otherwise, you must either accept the energy dependence and the
innaccuracies that come with a "middle ground" beta factor, or redesign the
dosimeter to provide some discrimination for beta energy.

If a filter over one of the other elements can be made thin enough (about
300 mg/cm2 or less) to permit response to high energy beta while still
performing its other intended function, beta energy discrimination is
possible. The math may be a bit complicated in mixed radiation fields
containing beta, but it can be done.
Bob Flood
Unless otherwise noted, all opinions are mine alone.
(415) 926-3793
bflood@slac.stanford.edu