Status of the new Los Alamos UCN source

Ultra-cold neutrons (UCN) have been produced at reactors over the last 30 years. Although very successful, experiments often suffer from low UCN statistics—as limited by the traditional production scheme. A new type of UCN source has been developed at Los Alamos. The source combines a spallation target, a cold neutron flux trap, and a solid deuterium converter for the down-scattering of cold neutrons into the ultra-cold regime. The breakthroughs of the last year include the theoretical understanding of the production mechanism and its experimental verification. The new technique is capable of delivering orders of magnitude higher densities of UCN. The highest UCN density ever stored in an experiment is reported.