Source: wikibot/ultracold-neutrons
= Ultracold neutrons
{wiki=Ultracold_neutrons}
Ultracold neutrons (UCNs) are neutrons that have been cooled to very low temperatures, typically below 1 microelectronvolt (µeV) in energy. This extreme cooling reduces their kinetic energy, making them nearly stationary relative to other particles. Ultracold neutrons are produced when thermal neutrons are either scattered off surfaces that reflect them or when they undergo specific interactions that reduce their energy.