Mass Attenuation Coefficient - Defining Equations

Defining Equations

The defining equation for the mass attenuation coefficient is essentially a different way to write the Beer-Lambert law. The Beer-Lambert law is normally written

where

I₀ is the original intensity of the beam,

I is the intensity of the beam at distance into the substance,

e is Euler's number, about 2.718,

is the attenuation coefficient.

When discussing the mass attenuation coefficient, this equation is rewritten

where

is the density, is the mass attenuation coefficient and is the area density known also as mass thickness.

In accordance with the above, the mass attenuation coefficient is equal to the attenuation coefficient divided by the density.