[ RadSafe ] Infinite Thickness of KCl
Forsee, Gary
Gary.Forsee at illinois.gov
Tue Aug 30 15:38:41 CDT 2011
Afternoon Erik,
I'm going stick my head out there and take a shot at this:
Assuming you are blocking any dose contribution from alpha and beta, and
only measuring the gamma contribution then I would recommend solving the
equation below:
T = exp( -mu / p * x )
Set the transmittance (T) equal to zero, indicating the point where the
1460 keV gamma is completely absorbed. -mu/p (email wont support the
Greek mu)is the mass attenuation coefficient, specific to the keV of the
gamma and the density of the material - input as cm2/g. The website
below has the mass attenuation coefficients for varying Z of materials
across the energy ranges of 10 keV to 1 MeV.
http://physics.nist.gov/PhysRefData/XrayMassCoef/tab3.html
'x' is the thickness of material (in centimeters) that will be required
to absorb the 1460 keV gamma.
G. Forsee
-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of
Nielsen.Erik at epamail.epa.gov
Sent: Tuesday, August 30, 2011 11:50 AM
To: radsafe at health.phys.iit.edu
Cc: liste de distribution pour les RADIOCHIMISTEs
Subject: [ RadSafe ] Infinite Thickness of KCl
I am trying to determine the infinite thickness of the 1460 keV gamma
emission (10.5% abundance) of a planar source of KCl (416 pCi/g) and a
density of 1.98 g/cc.
In other words, what is the thickness of a KCl planar source where any
additional thickness does not increase the surface dose rate?
I have scoured my references but have not located the appropriate
formula
for calculating this value.
I would appreciate any references or suggestions for an appropriate
calculation.
Erik C. Nielsen
USEPA, National Air and Radiation Environmental Laboratory
540 South Morris Ave.
Montgomery, AL 36115
Phone 334-270-3475
Fax 334-270-3454
"Those who do not read are no better off than those who cannot"
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