Re: Electronic Dosimeter for 100 nanosecond x-ray pulses

[tdc@ehssun.lbl.gov]

I doubt your pressurized ion chambers will fit the bill!

What you are asking is very difficult - almost mutually exclusive with an
ion chamber.

You want high sensitivity - 50 - 200 mR resolution which requires volume

YET you need high saturation which requires a high gradient.

When you combine the gradient with the size necessary - the end result is
usually breakdown!

Pressure helps lower the gradient and/or reduce the size - but requires a
thicker wall that degrades low energy sensitivity.  In your case the energy
is high - but still.....

The highest rate commercially available survey meter I know of that will
reasonably resolve low levels is the HPI 1030 - but it misses the high
rate mark by a few orders of magnitude.

There are also thimble chambers used commonly for measuring diagnostic
x-ray beams.  A 15cc chamber I have will work in the exposure range you
need - but still will not maintain saturation and 2 million R/sec!

I THINK I saw a poster given by LANL that talked of a solid state detector
they are working on that MIGHT fit your bill.  I KNOW it is fast enough -
but I cannot recall if it is sensitive enough.

Ted de Castro
tdc@ehssun.lbl.gov
University of California Lawrence Berkeley Laboratory
Bldg 90 Rm 0026B
Berkeley, CA 94720
(510) 486-5256
(510) 486-6939 - FAX