(physics) A nuclear reaction in which one or more neutrons are emitted. / A form of radioactive decay, where a nucleus with a severe excess of neutrons, emits a neutron.

(nuclear physics) A neutron produced immediately by the fission of an atomic nucleus, instead of being emitted by decaying fission products seconds to minutes later; over 99% of all fission neutrons are prompt neutrons (the exact proportion depends on the nuclide undergoing fission).

(nuclear physics) A neutron produced as a result of nuclear fission which is emitted upon the radioactive decay of a fission product nucleus seconds to minutes later, rather than at the time of the initial fission event. Less than 2% of fission neutrons are delayed neutrons (the exact proportion depends on the nuclide being fissioned).

(physics) The jagged line, on a chart showing the number of protons and neutrons of all known isotopes, beyond which neutron-rich nuclei are unstable and emit neutrons.

(physics) The cross section (probability) of a neutron capture reaction

(inorganic chemistry) An analytical technique that measures the decay of elements when bombarded with neutrons

plural of proto-neutron star

(stars) The degenerate core of a massive star, prior to its emergence after a supernova as a neutron star.

plural of neutron drip line

plural of neutron cross section