Linear attenuation coefficient

The linear attenuation coefficient, attenuation coefficient, or narrow-beam attenuation coefficient characterizes how easily a volume of material can be penetrated by a beam of light, sound, particles, or other energy or matter. A coefficient value that is large represents a beam becoming attenuated as it passes through a given medium, while a small value represents that a beam will experience little or no loss in the medium. The (derived) SI unit of attenuation coefficient is the reciprocal metre (m). Extinction coefficient is another term for this quantity, often used in meteorology and climatology. The attenuation length is the reciprocal of the attenuation coefficient.