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Re: Re[2]: Ionization at 80 eV? (Yes)
At 08:39 AM 5/19/97 -0500, you wrote:
>
> I'm confused. I was under the impression that the Geiger-Muller
> region was at a distinctly higher voltage than the Proportional
> region. My DOE Fundamentals of Instrumentation book places the
> Proportional region of the gas ionization curve at between ~300 and
> ~800 volts and the Geieger-Muller region at ~1000 to ~1400 volts. I'm
> guessing that these curves are gas dependant (the handbook is quiet on
> just what gas the curve is relevant to).
>
> A GM Tube at 900 volts and a proportional detector at 4000 volts
> doesn't make sense to me unless the ionization curve is gas dependant
> and differing gases are used in each. Is this the case?
>
> This is of interest to me since my FacRep oral board is tomorrow and I
> may or may not have to talk about the mechanics of radiation
> detectors. (Probably not, but better safe than sorry.)
>
> Jeff King
> US DOE Facility Representative
> Savannah River Operations Office
> In-Tank Precipitation Facility
>
Dear Jeff,
You are partly right: In a given device, the Proportional Region lies
below the GM-Region. However, the determining quantity is not the voltage
but the electrical field. I have use 8,000 Volts in a proportional counter
of large dimensions. Actually, for experimental reasons, the cross-section
was a square!! It worked as well as was needed.
Best regards
Fritz Seiler
******************************************************
Fritz A. Seiler
Institute for Regulatory Sigma Five Associates
Science, Western Office 4101 Lara Dr. NE
P.O. Box 14006 Albuquerque, NM 87111
Albuquerque, NM 87191,USA USA
Tel: xx-505-323-7848 xx-505-292-0392
Fax: xx-505-293-3911 xx-505-293-3911
e-mail: seiler@nrsi.org faseiler@nmia.com
All statements represent the author's opinions and not
the opinions or policies of any firm or institution.
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