How is a neutron produced in radioactive decay and nuclear fission?

In the context of physics, neutrons are produced through distinct mechanisms in radioactive decay and nuclear fission.

Nuclear Fission

In nuclear fission, a heavy nucleus splits into two smaller fragments, liberating energy and neutrons. These neutrons are categorized into two types:12
* Prompt Neutrons: These are emitted almost instantly at the moment of scission, primarily from the recoiling fission fragments as they release internal excitation energy.3
* Delayed Neutrons: These are produced when certain fission products undergo beta decay to an excited state of a daughter nucleus. If the decay energy exceeds the binding energy of a neutron in that daughter nucleus, a neutron is emitted. This emission is "delayed" because it is governed by the half-life of the precursor's beta decay.4

Radioactive Decay

While most common forms of radioactivity involve the emission of alpha particles, beta particles, or gamma rays, neutrons can be produced in rare, specialized processes:
* Beta-delayed neutron emission: Similar to the delayed neutrons in fission, this occurs when a nucleus undergoes beta decay to a highly excited state that subsequently emits a neutron.5
* Spontaneous Fission: Some heavy, unstable nuclei undergo spontaneous fission, a form of radioactive decay where the nucleus splits into two fragments and emits a few neutrons.6