Producing a free neutron
In a nuclear reactor
Neutrons are produced by the fission of fissile nuclei impacted by slow neutrons. Each fission event produces a large number of neutrons. Some of them are slowed down to sustain additional fission reactions, while another part escapes from the reactor.
Examples: ILL, ORPHÉE
Diagram of a nuclear reactor producing neutrons.
In a spallation source
Neutrons are produced by the collision of very high-energy protons (> ~80 MeV) with heavy nuclei. The nuclei are broken apart or excited, emitting a large number of neutrons.
Examples: ISIS, ESS
Neutron production by spallation.
In a CANS
Neutrons are produced by the collision of medium-energy protons (< ~80 MeV) with light nuclei. The nuclei become excited and can de-excite by emitting neutrons.
Example: ICONE
Diagram of a Compact Accelerator-based Neutron Source (C