Re: Critics Allege Infant Mortality Rate

[Franz Schoenhofer <schoenho@via.at>]

At 18:22 27.04.2000 -0500, you wrote:
>Hi Bob,
>
>The info for the technique might be on the webpage: www.radiation.org
>I don't recall exactly, it was something like a spellation counter, but that
>might not be the correct name for the machine.
>

Norm and RADSAFErs,

Sorry, having once worked to develop new methods for Sr-90 measurement I
again cannot resist to answer - it seems this is my third reply to the story.

You obviously refer to a "liquid scintillation counter", the type of
instrument I have based all my new methods on. I use to say that liquid
scintillation spectrometry is my secret love....

Of course liquid scintillation spectrometry offers considerable advantages
over the older measurement methods like Geiger-Müller counters and the
instruments I used (the "Quantulus" of Wallac) even offer the possibility
to do beta-spectroscopy and therefore are very valuable to detect
interferences from other radionuclides. (If K-40 would be present in not
negligible quantities then it would be detected. By the way it is funny,
that the higher the beta-energy is, the higher is the counting efficiency -
totally different from Ge-gamma-spectrometry!)

But in the case of beta-emitters (and of course alpha-emitters) the use of
certain measurement methods is not the limiting factor, it is the
preparation of a very pure sample of the radionuclide, separating from any
interfering radionuclides. Different measurement equipment will give you
different lower limits of detection and will in some cases require
correction methods for instance for source thickness.

I am getting more and more interested about the methods used in the Tooth
Fairy Project. Were the laboratories certified?

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:
Hofrat Dr. Franz Schoenhofer
Federal Ministry of Agriculture, Forestry, Environment and Water Management
Radiation Protection Department (BMLFUW I/8 U)
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phone: -43-1-71172-4458
fax: -43-1-7122331

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