physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...

, the attenuation length or absorption length is the

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...

\lambda

into a material when the

probability Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speaking, ...

has dropped to

1/e

that a

particle In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from ...

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

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 The Beer–Lambert law, also known as Beer's law, the Lambert–Beer law, or the Beer–Lambert–Bouguer law relates the attenuation of light to the properties of the material through which the light is travelling. The law is commonly applied t ...

: :

P(x) = e^ \!\,

. In general

\lambda

is material and energy dependent.

References

* * 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 Particle physics Experimental particle physics {{particle-stub

See also

References

External links