"Inspector" photon response

["Heinmiller, Bruce" <heinmillerb@AECL.CA>]

S.E. International manufactures a small ratemeter/scalar that they call the
Inspector that uses a built-in ostensibly uncompensated G-M pancake
detector, and has a removable metal swipe-counting slide so that it can
function as a contamination monitor.  I have an interest in possibly
acquiring this instrument to serve as a portable environmental photon survey
meter as well.

Does anyone have information on its energy and angular response (with the
slide in place) with regard to measuring some specific quantity such as
exposure (or air kerma), or ambient dose equivalent?

Their spec sheet suggests that the rate quantity it's intended to measure
(in addition to count rate) is exposure rate, as the units given in their
accuracy specifications are mR/h, referenced to Cs-137.  There is an option
for displaying units of microSv/h as well, and because there is an easily
set calibration factor adjustment, a quantity such as ambient dose
equivalent may be adequately measurable (I'm not after perfection here) if
the energy- and angular response is appropriate.

The spec sheet gives an energy response (for which the reference quantity is
not given but which I assume is exposure) which must be for radiation
incident on the thin window, because the response at 10 keV is about one (as
opposed to zero through, say, 1 mm of iron) with respect to Cs-137.  Quite
aside from the fact that I'm not interested in the thin-window photon energy
response, I never trust these data for superficial detector sensitive
elements because of ambiguity with regard to the degree of type-test
exposure collimation.  In particular, even with sufficient source build-up
material, there may be a large surplus or deficit of electrons with respect
to the SCPE complement.

Are there any type-test data out there?  Of particular interest would be,
say, some indication of its isotropic response as a function of photon
energy, and its energy response for a parallel-beam photon field incident on
the swipe-counting slide.

I'd appreciate any information be sent to me directly at the address below,
or to radsafe if it's likely to be of interest to others.

Bruce Heinmiller CHP
AECL
Chalk River Laboratories
Chalk River, Ontario, Canada
K0J 1J0
heinmillerb@aecl.ca


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