A radiation detector having glass emitting photons by scintillation in response to incident neutrons and/or electromagnetic radiation of at least about 1 keV, and a system associated with the glass for detecting the presence of photons emitted by scintillation. The glass ceramic material is a fluoride glass matrix having nanocrystalline particles distributed therein substantially all of which are in a phase that scintillates with average diameters of less than about 100 nm in a fluorozirconate matrix. Various metals are disclosed for the ceramic particles and methods of manufacture are also disclosed.