Medium-sized devices Plasma focus and plasma pinch devices Some accelerator-based neutron generators induce fusion between beams of deuterium and/or tritium ions and metal hydride targets which also contain these isotopes. 2 H ( deuterium) + >2.26 MeV photon → 1 neutron + 1H.9 Be + >1.7 MeV photon → 1 neutron + 2 4He.Gamma radiation with an energy exceeding the neutron binding energy of a nucleus can eject a neutron ( photoneutron). Radioisotopes which decay with high-energy photons co-located with beryllium or deuterium Usual combinations of materials are plutonium- beryllium (PuBe), americium-beryllium (AmBe), or americium- lithium (AmLi). The size and cost of these neutron sources are comparable to spontaneous fission sources. The useful lifetime for such sources depends on the half-life of the radioisotope. An alpha-beryllium neutron source may produce about 30 neutrons per 10 6 alpha particles. Alpha neutron sources typically produce ~10 6–10 8 neutrons per second. Thus, one can make a neutron source by mixing an alpha-emitter such as radium, polonium, or americium with a low-atomic-weight isotope, usually by blending powders of the two materials. Neutrons are produced when alpha particles hit any of several light isotopes including isotopes of beryllium, carbon, or oxygen. Radioisotopes which alpha decay mixed with a light element A typical 252Cf neutron source emits 10 7 to 10 9 neutrons per second when new but with a half-life of 2.6 years, neutron output drops by half in 2.6 years. 252Cf neutron sources are typically 1/4" to 1/2" in diameter and 1" to 2" in length. 252Cf and all other SF neutron sources are made by irradiating uranium or a transuranic element in a nuclear reactor, where neutrons are absorbed in the starting material and its subsequent reaction products, transmuting the starting material into the SF isotope. The most common spontaneous fission source is the isotope californium-252. Some isotopes undergo SF with emission of neutrons. Neutron source variables include the energy of the neutrons emitted by the source, the rate of neutrons emitted by the source, the size of the source, the cost of owning and maintaining the source, and government regulations related to the source. Neutron sources are used in physics, engineering, medicine, nuclear weapons, petroleum exploration, biology, chemistry, and nuclear power. Fundamental research with neutrons: Ultracold neutrons Ī neutron source is any device that emits neutrons, irrespective of the mechanism used to produce the neutrons.For neutron sources used in nuclear weapons, see modulated neutron initiator.
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