Radiative Capture of Neutrons

the nuclear reaction (n,γ), in which the target nucleus captures a neutron and the excitation energy of the nucleus formed is radiated as a gamma quantum. The probability of radiative capture depends on the properties of the target nucleus and the energy ℰ of the neutron. The probability generally decreases with increasing ℰ (resonance radiative-capture reactions are exceptions). For slow neutrons, the effective cross section of radiative capture is proportional to ℰ^–½.

Investigation of the gamma-ray spectrum of radiative capture permits determination of such characteristics of the nuclei formed as energy levels, spins, and parities. Extensive use is made of radiative capture in the production of radioactive isotopes and, consequently, in allied fields. Radiative capture is the principal process responsible for neutron absorption during the operation of nuclear reactors; it is used to control reactor operation.