Kinetic Model of Energy Relaxation in CsI:A (A = Tl and In) Scintillators

Abstract

A model of energy relaxation in alkali halide scintillators doped with Tl-like activators is presented. Interaction between thermalized charge carriers, their diffusion, and capture by traps are considered. The model of energy relaxation suggested in the work includes essential electron excited states in alkali halides doped with Tl-like activators. Self-trapping of holes occurs in alkali halides at LNT, giving rise to creation of self-trapped excitons (STEs). Thallium-like activator impurity can act both as an electron or a hole trap. Once both of the charge carriers are trapped by the dopant, activator recombination channel comes to action. The model is verified using CsI classical scintillation crystals doped with thallium and indium ions in a range of concentrations from 10–4 to 10–1 mol %. Temperature dependences of the STE and the activator-induced emission yield are measured as a function of the activator concentration under continuous X-ray excitation. A system of rate equations is used to simulate the applicability of the model under different excitation conditions. Evaluation of the parameters of the system is done for a numerical solution. The model of energy relaxation suggested allows to explain energy losses in CsI:A scintillators in a 10–300 K temperature range.

Particle detection at cryogenic temperatures with undoped CsI

“…This component is consistent with previous measurements of undoped CsI scintillation at low temperature [5,44] Below 10 K, the structure becomes more complicated, with several components contributing equal amounts of light to the pulse. We see a short component of the order 100 ns from both αs and γs, consistent with the 290 nm emission, and a long component that is consistent with the 338 nm emission, which are described by previous studies as a system of three excitonic absorption bands [20,38]. There are several very long time constants present at high temperatures that seem to hold a constant value of 10 µs and 100 µs, which could be attributed to coincidence within our acquisition window of α and γ events.…”

“…There is some evidence that the non-proportionality of the LY in pure CsI depends on temperature. Lu et al [45] report that at 295 K, the LY of a 60 keV γ-interaction is greater than that of a [38] are shown by the solid green line, scaled to be equal to our result at 77 K. c) α/γ ratio (corrected) as a function of temperature, showing a factor 4 variation and reaching values greater than 1. In a) and b), conversion of detected photons to emitted ones requires a multiplication by roughly 70, though this does not affect ratio in c).…”

Operational Approach and Solutions of Hyperbolic Heat Conduction Equations

“…We omit the bulky result of the above integration for arbitrary n ∈ Integers, γ ∈ Reals, which can be computed with account for (9). In the particular case of given n and γ, for the example for n = −γ = 1, we obtain…”

“…A good description of the major numerical methods is given, for example, in [1][2][3][4][5][6]. Here they allow numerical modelling of complicated physical processes [7][8][9][10][11][12][13][14][15][16][17][18][19], including multidimensional heat transfer in rectangles and cylinders [20][21][22][23]. However, proper understanding of the solutions and of the obtained results can be best done when they are obtained in analytical form.…”

A continuum theory of scintillation in inorganic scintillating crystals

“…From a physical point of view such an equation expresses the conservation of charge density (normalized with respect to the electron charge e ≈ 1.6 · 10 −19 C) within R provided the following identification for the micromechanical quantities is done: 2 For instance the models developed into [14], [16], [39], have M = 2 (electron-hole and exciton carriers densities), those in [15] and [7] split between the electron and holes with M = 3, the model developed into [40] has M = 7 whereas those in [13] and [36] have unspecified M (M ≥ 11 in [13]). it is important to remark that (b , s) represents a system of external actions for R in the sense that we may assume that in an experiment they can be controlled and be disposed of.…”