[ 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. 




'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

for calculating this value.


I would appreciate any references or suggestions for an appropriate 



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"


You are currently subscribed to the RadSafe mailing list


Before posting a message to RadSafe be sure to have read and understood
the RadSafe rules. These can be found at:


For information on how to subscribe or unsubscribe and other settings
visit: http://health.phys.iit.edu

More information about the RadSafe mailing list