Magnetic trapping of ultracold neutrons - art. no. 055502

Three-dimensional magnetic confinement of neutrons is reported. Neutrons ar e loaded into an Ioffe-type superconducting magnetic trap through inelastic scattering of cold neutrons with He-4. Scattered neutrons with sufficientl y low energy and in the appropriate spin state are confined by the magnetic field until they decay. The electron resulting from neutron decay produces scintillations in the liquid helium bath that results in a pulse of extrem e ultraviolet light. This light is frequency downconverted to the visible a nd detected. Results are presented in which 500+/-155 neutrons are magnetic ally trapped in each loading cycle, consistent with theoretical predictions . The lifetime of the observed signal, 660(-170)(+290) s, is consistent wit h the neutron beta-decay lifetime.