Mass attenuation coefficient

Thus, it characterizes how easily a mass of material can be penetrated by a beam of light, sound, particles, or other energy or matter.

Mass attenuation coefficient is defined as where When using the mass attenuation coefficient, the Beer–Lambert law is written in alternative form as where When a narrow (collimated) beam passes through a volume, the beam will lose intensity to two processes: absorption and scattering.

This is a convenient concept because the mass attenuation coefficient of a species is approximately independent of its concentration (as long as certain assumptions are fulfilled).

The values of mass attenuation coefficients, based on proper values of photon cross section, are dependent upon the absorption and scattering of the incident radiation caused by several different mechanisms such as The actual values have been thoroughly examined and are available to the general public through three databases run by National Institute of Standards and Technology (NIST): If several known chemicals are dissolved in a single solution, the concentrations of each can be calculated using a light absorption analysis.

First, the mass attenuation coefficients of each individual solute or solvent, ideally across a broad spectrum of wavelengths, must be measured or looked up.

Mass attenuation coefficients of selected elements for X-ray photons with energies up to 250 keV.
Mass attenuation coefficient of iron with contributing sources of attenuation: coherent scattering , incoherent scattering , photoelectric absorption , and two types of pair production . The discontinuity of photoelectric absorption values are due to K-edge . Graph data came from NIST 's XCOM database.
Mass attenuation coefficient values shown for all elements with atomic number Z smaller than 100 collected for photons with energies from 1 keV to 20 MeV. The discontinuities in the values are due to absorption edges which were also shown.