Phosphors for Radiation Detectors

8Optically‐Stimulated Luminescent Dosimeters

Hidehito Nanto and Go Okada

Co‐creative Research Center of Industrial Science and Technology, Kanazawa Institute of Technology, Hakusan, Japan

8.1 Introduction

Interaction of ionizing radiation with matter is one of the most important and basic phenomena in radiation measurements and engineering. As incident radiation energy is absorbed by a material (or solid), a large number of free electrons and holes are generated via ionization and excitation processes. Usually, the generated electrons and holes collide with the host lattice and then reduce energy while generating secondary electrons. Eventually, the energy is completely lost by recombining to emit light or phonons (heat). During these processes, if localized trapping centers exist in the host, some of the radiation‐generated charges such as free electrons and holes are captured by some of these trapping centers. The trapped charges are metastable or sometimes completely stable. In the metastable state, when external stimulation by heat or light is given to the material, the metastable charges relax to the ground state radiatively (meaning to emit light) and return to the original state. The luminescence phenomenon due to the thermal stimulation is called thermally‐stimulated luminescence (TSL), while the one due to the optical stimulation is called optically‐stimulated luminescence (OSL). The luminescence intensities of TSL and OSL are proportional to the dose of ionizing ...