Re[2]: Low energy x-ray (8 kev) survey meter

[TDC@ehssun.lbl.gov]

>At 8 kev, you have "LESS" than 0.01% efficiency with a G.M. (pancake, even
>less with a end-window), but are exceeding 10% efficiency with a low
>energy scintillation probe!

8 keV is the characteristic - but there are photons all the way up to the
excitation potential.

You're right - I have NOT compared a GM and scintillator side by side - BUT
I have never found indications from the GM that weren't overwhelmingly
clear!  A LONG ways from "fluorescent paper in a darkened room".  And -
area monitors and dosimetry have yet to even suggest that I missed
anything.  I feel the GM is sensitive enough for any level that matters and
therefore will opt for the simpler more robust instrument.

I don't doubt a scintillator is more sensitive.  I just don't think I need
that much sensitivity.

Since our analytical machines are all enclosed - we usually get to measure
wider fields that in close.  But then when surveying in close (enclosure
overridden) there is ample intensity even in a narrow stray beam.

Have you often found leaks with your scintillator that were missed with the
GM?  How signficant were they?  Were they at all significant at a distance
of a few feet (where an enclosure would be)?

> Another 2 cents,

I believe that's the purpose of this forum - to discuss these kinds of
issues.  Thanks for the input.