Estimation of the Electron Thermalization Length in Ionic Materials

We report estimations of the thermalization length and the diffusion coefficient of photogenerated carriers in the insulator LiYF₄ as a function of their initial energy. Combining modeling of electron–phonon interaction and the detailed analysis of the kinetic response of fluorescent center Ce³⁺ under vacuum ultraviolet excitation, the thermalization length is obtained as a function of the initial kinetic energy of the electron. This parameter is essential for the description of the carrier recombination in the case of nonideal plasma conditions, where electrons and holes are strongly correlated. This approach also demonstrates the effect of a complicated structure of electronic band on the thermalization process, which impacts the complex nonproportionality response of materials under ionizing radiation excitation

Radioluminescence Sensitization in Scintillators and Phosphors: Trap Engineering and Modeling

The role of charge carrier trapping in determining radioluminescence (RL) efficiency increase during prolonged irradiation of scintillators has been studied by using YPO₄:Ce,Nd as a model material. The Nd³⁺ ions act as efficient electron traps minimizing the role of intrinsic defects. Different Nd contents were considered in order to point out the correlation between the trap concentration and the detected RL efficiency dose dependence. RL measurements as a function of temperature clarified the role of the trap thermal stability in determining the shape and the magnitude of such effect. We propose also a model based on trap filling which is able to describe accurately the complex processes which are involved