Re: COUNTING EFFICIENCY DETERMINATION

[Schoenhofer <schoenho@via.at>]

At 11:18 02.10.1996 -0500, you wrote:
>The procedure for detector system efficiency determination is straight
>forward if one has a NIST traceable standard of the radionuclide in question.
> If one does not have such a standard some facilities use other radionuclides
>with "similar" spectra.  Is anyone aware of a reference for this
>"Mis-Matched" technique?  Could you please share?  Thank you for your
>assistance.
>
>Carl Chamberlain
>eccsierra@aol.com
>
>======================================================================

Carl,

The question is of course which detector system and which radionuclides you
want to use and determine. In gammaspectrometry with HPGE detectors you can
construct an efficiency curve over the whole energy range using a "mixed
radionuclide source" and need not necessarily use the radionuclide you want
to determine. Mostly you have samples where you do not know beforehand what
kind of gamma emitting radionuclides might be in the sample. In liquid
scintillation spectrometry and alpha spectrometry you have to use of course
the same radionuclides for counting efficiency determination as you want to
determine. Only if it is the case of contamination or dose measurements you
may use "similar" radionuclides to determine an approximate efficiency. I
remember that for some applications a "mock-iodine" standard is available,
which is a mixture of other radionuclides than I-131, but with much longer
half life than I-131 (8.3 days).

Franz
Schoenhofer
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