ROLE OF ACTIVATOR AND VACANCY CENTERS IN THE DECAY OF THE GAMMA SCINTILLATORS OF CSI–NA CRYSTALS

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Abstract

The influence of the concentration of an activator (CNaI) and of plastic deformation on a change in the contribution of a slow component to the decay of the γ-scintillations of CsI–Na crystals was investigated, as well as the influence of CNaI on a change in the shape of the luminescence excitation spectrum in the region of absorption of activator centers (AC) and of vacancy-related centers (VRC) and also on a change in the intercenter time of deexcitation of the centers indicated. It is shown that AC and VRC participate in the photoluminescence and γ-scintillations of CsI–Na crystals. In the γ-scintillations, AC are responsible for the component τ′1 = 370 nsec, whereas the components τ1′ = 460 nsec and τ2 ∼ 2 μsec are associated with VRC. The reduction of τ1 from 770 to 560 nsec with an increase in CNaI from 2.10−3 to 3.10−2 mole% and from 570 to 470 nsec after plastic deformation of the crystals (ε = 5%) along the 〈111〉 axis is caused by a decrease in the number of VRC. The mechanisms underlying the γ-scintillations of the CaI–Na crystals containing AC and VRC and also the decrease in the number of VRC are discussed.

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