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Scintillating crystals as continua with microstructure: Basic facts and non deformable crystals

17 February 2022
2:00 pm
San Francesco Complex - Classroom 1

Scintillating crystals, both organic and inorganic (henceforth referred as Scintillators) act as wavelength-shifter. When they are hit by an ionizing radiation (gamma-rays) charged particles from the core and valence bands jump to the conduction band. These particles generates a particle shower and then recombines, some of them giving back the initial energy as photons in the visible range. For this reason scintillators are used as sensor in High-Energy Physics, in Medical Imaging, in Astrophysics and in Security devices . The whole phenomena is a multi-scale one: the generation of charged particles is a microscopic phenomena, their evolution and recombination take place at the mesoscopic scale and then the light propagation within the crystal obeys the law of anisotropic optics and photo elasticity. We present a continuum model for the evolution and recombination of charge carriers in inorganic scintillators by modelling the crystal as a continuum with microstructure. For non-deformable crystals the evolution of charge carriers is described by the means of a Reaction-Diffusion-Drift equation whose mathematical aspects shall be discussed in details. The model is then extended to deformable continua in order to encompass, besides the effects of the stress on scintillation, also coupled phenomena like elasto-mechanoluminescence, i.e. the generation of light by the means of mechanical stress.


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Fabrizio Davì - Università Politecnica delle Marche