Solid State Neutron Detector – Lithium Indium Selenide
Detecting thermal neutrons is a specialized area of instrument design because only a few, limited chemical isotopes have sufficient sensitivity (via neutron absorption cross-section). By products such as charged particles and ions provide the true means of detection, for example, typical reactions such as 10B(n, α)7Li or 6Li(n, α)3H. Finding materials that can include such key isotopes is vital to developing new solid state neutron detectors – an urgent need in light of diminishing supplies of 3He.
RMD is developing a technology based on the Lithium Indium Selenide (LiInSe2) to produce a solid state neutron detector. Similar to other semiconductors studied by RMD, Lithium Indium Selenide is a wide bandgap material capable of room temperature operation which produces signals induced through ionization. Separating neutron signals from those created by gamma-rays is easily accomplished through pulse height discrimination, as the neutron events yield over 4 MeV energy. RMD has grown ingots of LiInSe2 to 1” diameter and utilized both natural and enriched forms of Li (the enriched form can provide 90% neutron efficiency in only a 2 mm thickness).