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

[TDC@ehssun.lbl.gov]

Let me chime in on this one.

I read the two previous responses and agree with Ron that an ION chamber
would be the best to MEASURE with BUT there are serious geometry
considerations that make accurate measurements non-trivial - to say the
least.

I disagree with the use of a low energy scintilattor to MEASURE these beams
since their energy is on the steep shoulder of the instruments' response.
Since such and instrument is so energy dependant - in order to MEASURE the
x-ray dose - your would need to know the x-ray spectrum - which is a
daunting task - at least.

I would also restate Ron's caution that the characteristic radiation is NOT
the energy of MOST concern to the HP - but the bemstraulung continum.

But - I would suggest that there is not need to MEASURE these radiations -
but merely to DETECT them.  I feel the best policy is to detect them and
then eliminate tham when found - since this is so easy to do.  This leaves
nothing left to MEASURE.

For detection - I find a pancake GM plenty sensitive enough and allows a
quick survey.  IF we allowed open beam x-ray units (which we DO NOT) then I
might use an end window GM for closer work - but areas harder than that to
get into are not likely to accessible to personel either.

I seldom find any good reason to attempt to measure the primary beam - ONLY
in accident reconstruction.  This is another process that requires great
care and consideration.

Ted de Castro
X-Ray Safety Officer
tdc@ehssun.lbl.gov University of California Lawrence
Berkeley Laboratory Bldg 75B Rm 112A Berkeley, CA 94720 (510) 486-5256
(510) 486-5506 - FAX