Search results
Results from the WOW.Com Content Network
In nuclear physics, the concept of a neutron cross section is used to express the likelihood of interaction between an incident neutron and a target nucleus. The neutron cross section σ can be defined as the area in cm 2 for which the number of neutron-nuclei reactions taking place is equal to the product of the number of incident neutrons that would pass through the area and the number of ...
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 ...
Calculating the coefficients φ in homogeneous and heterogeneous mixtures, we get; φ hom = e −0,00625·68 = e −0,425 ≈ 0,65, φ het = e −0,00625·11,3 = e −0,0705 ≈ 0,93. The transition from homogeneous to heterogeneous medium slightly reduces the thermal neutron absorption in uranium.
In the context of ozone shielding of ultraviolet light, absorption cross section is the ability of a molecule to absorb a photon of a particular wavelength and polarization. Analogously, in the context of nuclear engineering, it refers to the probability of a particle (usually a neutron ) being absorbed by a nucleus.
The multiplication factor, k, is defined as (see nuclear chain reaction): k = number of neutrons in one generation / number of neutrons in preceding generation . If k is greater than 1, the chain reaction is supercritical, and the neutron population will grow exponentially.
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).
Nonradioactive 133 Cs capturing a neutron and becoming 134 Cs, which is radioactive with a half-life of 2 years; Many of the fission products with mass 147 or greater such as 147 Pm, 149 Sm, 151 Sm, and 155 Eu have significant cross sections for neutron capture, so that one heavy fission product atom can undergo multiple successive neutron ...
A neutron may pass by a nucleus with a probability determined by the nuclear interaction distance, or be absorbed, or undergo scattering that may be either coherent or incoherent. [1] The interference effects in coherent scattering can be computed via the coherent scattering length of neutrons, being proportional to the amplitude of the ...