Kudin A. Development of physics and technology bases of the crystal surface modification for correction of their scintillation parameters

Physics and technology bases of the crystal surface modification are developed for correction the characteristics of scintillation crystals. It has been shown that modification of crystal reflective surfaces is an effective method to improve the spectrometric characteristics of the scintillator independently on the crystal sizes. It has been shown that non-uniformity of light collection coefficient gives a main contribution to the intrinsic energy resolution. The possibility and efficiency of light conversion to the region of lower crystal absorption and refraction as well as to higher sensitivity of photo-receivers have been proved for CsI, CsI:Na and CsI:Tl by means of wavelength shifting coatings. On a base of developed organosilicon coatings and adapted technology of surface treatment the new method of leveling of axis non-uniformity of light output has been proposed. This method permits to improve significantly the energy resolution of CsI crystals and increase the light yield of fast component of scintillation and its contribution to total output. It has been shown that protective coatings must be applied on a crystal surface after relaxation of deteriorated layer near surface. It has been shown that a radiation-induced band of surface absorption is not appeared in CsI crystal with protective coatings up to critical dose of irradiation.