neutronaktivitet

Neutronaktivitet (neutron activity) is a term used in nuclear physics and engineering to describe processes related to neutrons, including their production, transport, and interactions with matter. In practice, it may refer to the neutron flux in a system or to the activity of radionuclides produced by neutron activation.

Neutron flux is the rate at which neutrons pass through a given area, typically expressed in neutrons per square centimeter per second (n/cm^2 s). The neutron population in a system such as a reactor evolves according to generation by fission and losses due to absorption and leakage, described by the effective multiplication factor k_eff.

Neutron activation occurs when nuclei capture neutrons and become radioactive isotopes. The concern is the induced activity A in the material, given by A = lambda N, where N is the number of activated nuclei and lambda is their decay constant. During irradiation, the production rate dN/dt = Phi * sigma * N_target leads to a buildup of activity that decays after irradiation ends according to the isotope’s half-life.

Applications include neutron activation analysis for elemental quantification, dosimetry in radiation protection, and material testing. Safe handling requires understanding neutron fluxes, cross-sections, decay schemes, and shielding considerations.