Analysis and experimental verification of neutron-activated LiF as a stable matrix for tritium beta sources

Abstract

Tritium (3H) has long been considered a useful radioisotope for many purposes due to its low-energy and pure beta decay. However, due to its aggressive migration, solid-state retention of tritium for use as a beta radiation source is challenging. Bulk-level infusion of tritium in a solid is often employed as a solution to effusion and outgassing but limits the beta radiation output due to the use of high-Z materials. This letter presents experimental and simulated analysis regarding the production and efficacy of a low-Z, solid-state tritium beta source. Single-crystal lithium fluoride (LiF) is used as a host matrix for tritium radionuclides, which are generated by the 6Li(n,α)3H reaction when the crystal is exposed to thermal neutron irradiation. The experimental findings present negligible outgassing of tritium from the material, while the simulation results suggest thickness optimization of the LiF/3H beta source. Moreover, the simulation results indicate significantly enhanced beta output efficiency compared to palladium tritide, which is a state-of-the-art tritium host. With proper thickness, the tritium-filled LiF matrix is a stable low energy beta source, which can be easily produced and incorporated into a variety of applications.