Boosting Ultracold Neutron Production with Low Enriched Uranium

Ultracold neutrons (UCNs) are free neutrons with energies low enough (<300 neV) to be manipulated by specific materials, gravity, and magnetism. Their ability to be stored in material bottles proves especially useful for fundamental physics experiments, including precise measurements of the neutron electric dipole moment, lifetime, and gravitational interactions at quantum scales. Despite advances in experimental design and detection technology, these experiments remain statistics-limited due to the inherently low flux of UCNs. An effort to increase UCN production yield includes the addition of a low enriched uranium cylinder in the UCN source assembly as a neutron multiplier. MCNP simulations support this effort to balance the neutrons sacrificed to fission with an increase in cold neutron flux in the converter volume.

LA-UR-25-26716.