2.6.2. Half-Thickness

Lambert’s Law describes the amount of attenuation that radiation undergoes passing through a material:

The concept of a "half-thickness" is particularly useful when discussing absorption. This is simply the thickness of material required to halve the intensity of X-ray (or any other) radiation. It may be calculated from Lambert's Law, noting that at the half thickness, the intensity of the radiation is halved (I = ½ I_o). Plugging in yields:

Taking the natural log of both sides of the equation yields:

Rearranging:

The natural log of 0.5 = -0.6931, so the final equation is:

Copyright 1997-2003, James H. Wittke

Last update: 01/18/2006 01:47 PM.