Attenuation length

In physics, the attenuation length or absorption length is the distance ${\displaystyle \lambda }$ into a material when the probability has dropped to ${\displaystyle 1/e}$ that a particle has not been absorbed. Alternatively, if there is a beam of particles incident on the material, the attenuation length is the distance where the intensity of the beam has dropped to ${\displaystyle 1/e}$, or about 63% of the particles have been stopped.

Mathematically, the probability of finding a particle at depth x into the material is calculated by Beer-Lambert law:

${\displaystyle P(x)=e^{-x/\lambda }\!\,}$.

In general ${\displaystyle \lambda }$ is material and energy dependent.

See also

• Beer's Law
• Mean free path
• Attenuation coefficient
• Attenuation (electromagnetic radiation)
• Radiation length

References

• S. Eidelman; et al. (2004). Particle Data Group (ed.). "Review of particle physics". Phys. Lett. B. 592.
• https://web.archive.org/web/20050215215652/http://www.ct.infn.it/~rivel/Glossario/node2.html

External links

• http://henke.lbl.gov/optical_constants/atten2.html