Model of ion-induced luminescence based on energy deposition by secondary electrons

Abstract

A model is proposed to describe the production of light induced by energetic ions in scintillator materials, based on the distribution of energy deposited by the secondary electrons produced along the ion’s track. The initial energy of the electrons is determined using an impulse approximation in which their motion is constrained to the radial direction, perpendicular to the ion’s track. The residual energy of the electrons along the radial coordinate is obtained from an expression for the specific energy loss obtained from Lindhard’s potential theory. Contributions from backscattered electrons to the energy deposition are included in the calculation. Local production of energy carriers is assumed to be proportional to the local density of deposited energy, in the absence of quenching effects. The latter are introduced by assuming the existence of a maximum energy density greater than which prompt quenching predominates and the energy carrier density reaches a maximum constant value. Light production is related to the process of energy transport through thermal diffusion of energy carriers to luminescence centers. Simple algebraic expressions are given for the energy deposition profile and for the specific luminescence. Model predictions are compared with published experimental data from various organic and inorganic scintillators.