Scintillation detectors of radiation: Excitations at high densities and strong gradients

Abstract

This chapter discusses the electron-hole recombination processes that occur in the high excitation densities and strong radial gradients of particle tracks in scintillator detectors of radiation. The particle tracks are commonly those of high-energy Compton- or photo-electrons produced in energy-resolving gammaray detectors, but could also include those of heavier charged particles such as those following interactionwith neutrons. In energy-resolving radiation detectors, intrinsic proportionality of light yield to gamma ray energy or electron energy is an important concern. This chapter gives special emphasis to understanding the physical basis for nonproportionality, while reviewing recent results on fundamental physics of nonlinear quenching, cooling and capture of hot electrons, co-evolving free-carrier and exciton populations, and diffusion in the dense and highly structured excitation landscape of electron tracks. Particular attention is paid to short-pulse laser experiments atWake Forest University giving data and insight on the above phenomena complementary to more traditional scintillator experiments using gamma-ray or electron excitation. Numerical modeling of diffusion, nonlinear quenching (NLQ), exciton formation, and linear capture processes serves to test and establish links between the laser excitation and particle excitation measurements.