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In physics, absorption cross-section is a measure of the probability of an absorption process. More generally, the term cross-section is used in physics to quantify the probability of a certain particle-particle interaction, e.g., scattering , electromagnetic absorption , etc. (Note that light in this context is described as consisting of ...
In physics, the cross section is a measure of the probability that a specific process will take place in a collision of two particles. For example, the Rutherford cross-section is a measure of probability that an alpha particle will be deflected by a given angle during an interaction with an atomic nucleus.
Two-photon absorption is a third-order process, with absorption cross section typically several orders of magnitude smaller than one-photon absorption cross section. Two-photon absorption was originally predicted by Maria Goeppert-Mayer in 1931 in her doctoral dissertation. [2]
The absorption neutron cross section of an isotope of a chemical element is the effective cross-sectional area that an atom of that isotope presents to absorption and is a measure of the probability of neutron capture. It is usually measured in barns. Absorption cross section is often highly dependent on neutron energy. In general, the ...
absorption cross section and scattering cross section are both quantitatively related to the attenuation coefficient; see absorption cross section and scattering cross section for details; The attenuation coefficient is also sometimes called opacity ; see opacity (optics) .
Nuclear cross sections are used in determining the nuclear reaction rate, and are governed by the reaction rate equation for a particular set of particles (usually viewed as a "beam and target" thought experiment where one particle or nucleus is the "target", which is typically at rest, and the other is treated as a "beam", which is a projectile with a given energy).
The oscillator strength is defined by the following relation to the cross section for absorption: [19] = =, where e {\displaystyle e} is the electron charge, m e {\displaystyle m_{e}} is the electron mass, and ϕ ν {\displaystyle \phi _{\nu }} and ϕ ω {\displaystyle \phi _{\omega }} are normalized distribution functions in frequency and ...
The mass attenuation coefficient (also called "mass extinction coefficient"), which is the absorption coefficient divided by density; The absorption cross section and scattering cross-section, related closely to the absorption and attenuation coefficients, respectively "Extinction" in astronomy, which is equivalent to the attenuation coefficient