Re: Respect

[Alan Watts <wattsa@oak.cats.ohiou.edu>]

C-14 can be measured with a Ludlum 3 Pancake GM considering the 10 - 12%
efficiency that is typical of such an instrument.

>Dear Diana,
>
>I read with some surprise your recent mail and after having read, that you
>know everything about this topic, all the shortcomings and that you are
>aware that the answer to your original question can be found in textbooks I
>am even more surprised, why you posted your question. I have offered you to
>give you information on possible tricky questions, but in spite of your
>mail I  still do not think that RADSAFE is a forum for really basic
>questions, which should be covered by basic training. Looking up a textbook
>is in my opinion not an extensive research.
>
>I am concerned with the attitude to measure radionuclides, which are
>difficult to measure because they are alpha- and/or beta emitters with the
>most simple equipment. If it has to be done, then the appropriate equipment
>and the appropriately trained personell has to be provided. If both
>equipment and personell cannot be provided then the measurements cannot be
>done - it is that simple.
>
>As to your original question:
>
>I understand from your last mail that the LUDLUM 3 is a GM pancake
>detector, which I have no practical experience with. With this you will not
>be able to measure tritium, so any measurement done with this instrument
>will not suffer from any interference from tritium. C-14 is a pure
>beta-emitter, but you will most probably not be able to measure a
>radionuclide with this low energy with the instrument you mentioned.
>Further pure beta emitters are of course Sr-90 and Y-90, but their
>measurement will hardly be possible in any matrix without chemical
>separation and special measurement equipment. As has been pointed out in
>one answer, Cs-137 is a beta emitter, but in practice Cs-137  is nowadays
>measured via the gamma-rays of the very shortlived daughter Ba-137m. Y-91
>it to my knowledge a pure beta-emitter, but it is shortlived and only
>present in fresh fallout from a nuclear accident. Other pure beta-emitters
>from the natural decay chains are associated with gamma-emitting daughters,
>so their concentration can be measured by gamma-spectrometry.
>
>In principle I have always had and still have the opinion that activity
>concentration measurements with GM-detectors in contamination monitors are
>not possible, unless only one radionuclide is present and it has been
>carefully calibrated with the same radionuclide in question and the same
>geometry. We have successfully used liquid scintillation spectrometry for
>measurement of beta-emitters and developed simple methods for various
>radionuclides.
>
>Any specific questions are welcome and I will try to delete in the future
>all basic ones.
>
>With my best regards,
>
>Franz
>
>
>Franz Schoenhofer
>Habicherg. 31/7
>A-1160 Vienna
>Austria
>Tel.: +43-1-495 53 08
>Fax.: same number
>mobile phone: +43-664-338 0 333
>e-mail: schoenho@via.at
>
>Office:
>Federal Institute for Food Control and Research
>Department of Radiochemistry
>Kinderspitalg. 15
>A-1095 Vienna
>Austria
>Tel.: +43-1-40 491 520
>Fax.: +43-1-40 491 540
>e-mail: schoenhofer@baluf.via.at
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