Luminescence response of CsI:Na to electron pulse irradiation

This paper investigates the influence of activator concentration and temperature on the scintillation process in CsI:Na crystal which was excited by a pulsed electron beam (E-ex = 0.25 MeV, t(1/2) = 15 ns, W = 0.003...0.16 J/cm(2)) at temperature within 77-300 K. It has been established that the transition of Na-bound two halide exciton from singlet state causes 3 eV emission of CsI:Na. The capturing of V-k by Na+ ion determines the scintillation pulse shape. Thermal liberation of V-k from V-kA centers results in an inertial rise of the emission pulse in lightly activated CsI:Na and in a mono-exponential decay of the emission pulse in heavily activated CsI:Na. The value of thermal dissociation energy of V-kA centers is 0.24 +/- 0.01 eV, which was obtained from the temperature dependences of the emission decay time constant for CsI:2.8.10(-3)%Na and of the rise time constant for CsI:2.0.10(-4)%Na. (C) 2013 Elsevier Ltd. All rights reserved.