Zosym D. Long scintillation position - sensitive gamma - radiation detectors

The thesis is devoted to investigation and solution of the problem of the crea-tion of a new method for position-sensitive detection of ionizing radiation fluxes by means of scintillation crystals, as well as to establishment of regularities in the influ-ence of the properties of the crystals on the formation of their position sensitivity. It is shown that non-uniform monotonously decreasing distribution of the light yield from one end of a long scintillation crystal to the other end allows to create position-sensitive scintillation detectors. Linear or exponential decrease of the light yield along the crystal axis is provided by special conditions of light collection in scintillation crystals defined by their structure and optical perfection. The coordination resolution is shown to be defined by the energy resolution of the scintillator and by the non-uniformity of the light yield distribution along the crystal axis. For CsI(Tl) crystals the optimum value of such a non-uniformity must belong to the interval from 0,7 to 0,5. In order to achieve reproducible results of light collection in CsI(Tl)-based detec-tors with a height/cross-section ratio of 9-10, the boundaries of the concentration plateau of the dependence "light yield - activator concentration" should be 0,092 - 0,114 weight %.