Simple model relating recombination rates and non‐proportional light yield in scintillators

Abstract

We present a phenomenological approach to derive an approximate expression for the local light yield along a track as a function of the rate constants of different kinetic orders of radiative and quenching processes for excitons and electron-hole pairs excited by an incident ! -ray in a scintillating crystal. For excitons, the radiative and quenching processes considered are linear and binary, and for electron-hole pairs a ternary (Auger type) quenching process is also taken into account. The local light yield (YL) in photons per MeV is plotted as a function of the deposited energy, -dE/dx (keV/cm) at any point x along the track length. This model formulation achieves a certain simplicity by using two coupled rate equations. We discuss the approximations that are involved. There are a sufficient number of parameters in this model to fit local light yield profiles needed for qualitative comparison with experiment.

Comparative Study of Nonproportionality and Electronic Band Structures Features in Scintillator Materials

“…Different types of energy carriers such as excitons and electron and hole pairs may exist in a crystal. The idea that both type of excitations (exciton and free e/h) may be present in a scintillator and that their relative proportion affects the shape of the light yield response is adapted in a recent phenomenological model relating recombination rates and nonproportionality [17]. Assuming similar carriers' lifetime in a particular scintillator, the spatial distribution of free charge carriers is sensitive to the difference in their effective masses.…”

“…Fortunately, the development of the Compton Coincidence [4,10]. The simulations were used to determine the energy loss rate dE/dx that enabled the calculations of the density of activated sites n(ρ,x,t) and the local light yield produced by these activated sites using a kinetic model that accounts for spontaneous emission, quenching, and transfer rates [17]. A different research approach was undertaken to relate nonproportionality to relevant material parameters.…”

The role of different linear and non-linear channels of relaxation in scintillator non-proportionality

“…1 (right axis). The model of the cylindrical track has been used in most papers which study non-proportionality [1,[9][10][11].…”

“…Some of our attempts for the phenomenological description of the excitation density dependence of the yield are also presented in Refs. [11,12].…”

Kinetic Monte Carlo simulations of excitation density dependent scintillation in CsI and CsI(Tl)

“…These elementary processes include the creation of excited states, the transport of excited carriers through the scintillator lattice, and the quenching of excitations as they propagate. Approaches employed to model these processes include minimalist phenomenological models , kinetic models , diffusion models , and microscopic models that explicitly deal with individual electron–hole pairs .…”