ИСТИНА

Intraband luminescence (IBL) is a fast emission occurring in insulating crystals during electron and hole thermalization after the interaction of ionizing radiation with wide-band-gap crystals. This type of luminescence, in spite of its low quantum yield, is characterized by sub-picosecond rise time and picosecond decay time and could serve as a basis for fast timing for registration of ionizing radiation. The 10 ps goal is a contemporary request for nuclear medicine devices (namely, time-of-light positron-emission tomography) and for calorimeters in high energy physics for future accelerators with high luminosity. This work is aimed at the development of a theoretical model that allows to calculate IBL parameters, such as quantum yield, spectrum and kinetics, based on the band structure of substances. It is expected that this model will simplify and accelerate the experimental search for substances with a high quantum yield of IBL. In papers [1-2], the spectrum and quantum yield of IBL were calculated in the approximation of one parabolic branch of the electron dispersion law in the conduction band. Unfortunately, within the framework of this model, the IBL parameters cannot be fully reproduced, since direct radiative transitions are impossible. Therefore, within the framework of the present work, it was decided to develop a theoretical model of IBL for the case of multiple parabolic branches of the electron dispersion law in the conduction band. Developing this model, expressions were obtained describing the rates of nonradiative electronic transitions with absorption or emission of phonons, as well as expressions describing the rates of radiative transitions: direct (with emission of photons) and indirect (with simultaneous emission of photons and emission or absorption of phonons). Using the Monte Carlo method, the dependencies of these rates on the electron energy for cesium iodide were calculated. Then, based on the results of the calculations, the spectrum and quantum yield of IBL were obtained. [1] Vasil’ev, A. N., and R. V. Kirkin., Physics of Wave Phenomena 186-191 (2015) 23.3. [2] Omelkov, S. I., et al., Journal of Luminescence. 309-317 (2016) 176.