Neutroninduced

Neutron-induced describes nuclear reactions initiated by the interaction of a nucleus with one or more neutrons. These reactions include radiative capture (n,γ), inelastic scattering (n,n'), neutron emission (n,2n), fission (n,f), and, less commonly, particle emission channels such as (n,p) and (n,α). The term is often used to distinguish such processes from those induced by charged particles.

Cross sections depend strongly on neutron energy. Thermal neutrons (around 0.025 eV) commonly undergo capture on many isotopes, with cross sections that often follow a 1/v trend at low energies. Fast neutrons (MeV range) are more likely to cause fission in fissile materials like 235U and 239Pu and to initiate other reactions such as (n,2n). The distribution of possible channels and their probabilities determine the neutron economy of a system and influence reactor design, radiation shielding, and isotope production.

Applications include nuclear power generation, where neutron-induced fission sustains a chain reaction; neutron activation analysis, which relies on neutron capture to produce radioactive tracers for material characterization; and production of medical isotopes. In astrophysics, neutron-induced reactions contribute to the synthesis of heavy elements via the s-process and r-process.

Measurement and evaluation of neutron-induced cross sections employ time-of-flight experiments, activation methods, and reactor- and accelerator-based sources. Results are compiled in nuclear data libraries to support simulations and safety analyses. The field intersects with nuclear theory through models of the compound nucleus and direct reaction mechanisms.