UCNτ Magneto-Gravitational Trap

The LANSCE Ultracold Neutron (UCN) source is a unique facility that produces high energy spallation neutrons. UCNs have some unique properties that allow them to be studied precisely: they move at speeds of only a few meters per second, and are completely confined by magnetic fields and material bottles for many hundreds of seconds at a time. These properties lead to very precise low energy particle physics experiments. There are several new and on-going experiments at the UCN source that measure decay correlations and other properties of the neutron. UCNτ, or the neutron lifetime experiment, utilizes a magneto-gravitational trap to contain ultra-cold neutrons without material interaction. The trap is lined with a Halbach array, a window-frame electromagnet, and uses strong magnetic fields to bind UCNs from the top.

A schematic of the UCNτ experiment. (NSF UCNτ Collaboration)