Scintillating Crystals as Continua with Microstructure

A scintillator material converts ionizing radiations into visible light. The process, a microscopic one related to the band gap energy in the atoms, is mediated by excited charge carriers which evolve and recombine in photons. Such recombination process evolves at a scale between the microscopic scale and the macroscopic scale of the bulk crystals. Here we show how this evolution process can be modeled with the mechanics of a continua with microstructure. By the means of thermodynamics we arrive at constitutive relations which lead to a reaction-diffusion-drift coupled system. Such a system resembles those already obtained, by starting from a different approach, for semiconductors. The mathematical study of these equations gives an insight about some properties of scintillator crystal which are confirmed by known experimental results.