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Phone: þ33 472 43 14 53, Fax: þ33 472 43 11 30The behavior of light yield in a wide range of inorganic scintillation crystals formed by isovalent substitution of anions or cations was investigated. The correlation between improvement of light yield in mixed crystals, and the ratios of volumes occupied by the competing atoms (ions) has been analyzed. A phenomenological approach to the prediction of light yield in mixed scintillation crystals allows us to predict the optimal combination of mixing components to reach the best scintillation performance.Relation between the rate of light-yield improvement and ratio of the volumes occupied by the substituted atoms.

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This work presents the Czochralski growth of SrI2:Eu scintillation crystals. SrI2:Eu is among the brightest recently discovered scintillators with an excellent energy resolution for spectroscopic identification of radioactive isotopes. The Czochralski crystal growth method is optimal from the point of scaling up of crystal production with minimal investment into upgrade of crystal growth equipment. In this study SrI2:Eu crystals with the diameter of up to 50 mm were produced by the developed process based on the Czochralski method. The crystals are prone to cracking, and thermal fields in the crystallizer still should be optimized. Nevertheless the scintillation parameters of detectors cut from the grown crystals are similar to that in detectors fabricated by the conventional Bridgman-Stockbarger technology. The Eu2+ activator concentration across the crystals is uniform within 5%, as well as the energy resolution, which ranges within 3.6±0.1% at 662 keV. Also, the decay times under X-rays, and non-proportionality of scintillation light yield on excitation energy in the range of 31-1274 keV have been determined.

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The Auger decay of a core hole results in appearance of several strongly correlated excitations. This excited region strongly polarizes the lattice and thus the defect creation is possible. In all cases the core hole causes the strong local perturbation of electronic and lattice subsystems. The creation of such excited region with mutual relaxation of correlated electrons and holes can result in the increase of the efficiency of energy transfer to activators, acceleration of the luminescence kinetics, and the appearance of radiation-induced luminescence centers.