Editing Neutron (section)

=== Neutron detection by neutron capture ===
A common method for detecting neutrons involves converting the energy released from [[neutron capture]] reactions into electrical signals. Certain nuclides have a high neutron capture [[cross section (physics)|cross section]], which is the probability of absorbing a neutron. Upon neutron capture, the compound nucleus emits more easily detectable radiation, for example an alpha particle, which is then detected. The nuclides {{SimpleNuclide|Helium|3}}, {{SimpleNuclide|Lithium|6}}, {{SimpleNuclide|Boron|10}}, {{SimpleNuclide|Uranium|233}}, {{SimpleNuclide|Uranium|235}}, {{SimpleNuclide|Neptunium|237}}, and {{SimpleNuclide|Plutonium|239}} are useful for this purpose. <!-- The following needs correction, errors due to lack of reference: These nuclides are rarely found in nature, but can be accumulated through processes such as isotopic enrichment.

The cross section for the process of neutron capture is much lower at high energies than at low energies. Therefore, the detection of neutrons by neutron capture requires a preceding slowing down of neutrons. For this purpose, a [[neutron moderator]] is used, typically a thick slab of polyethylene. Neutron detectors using the moderate-and-capture approach cannot measure neutron energy, precise time of arrival, or direction of incidence, because this information is lost during moderation. -->