Phosphors for Radiation Detectors

3Inorganic Oxide Scintillators

Daisuke Nakauchi, Noriaki Kawaguchi, and Takayuki Yanagida

Nara Institute of Science and Technology, Ikoma, Japan

3.1 Introduction

A wide variety of inorganic scintillators such as single crystals, polycrystalline ceramics, and glasses have been developed depending on their application. Following the discovery of X‐rays, ZnS and CaWO₄ powders have been used as photographic film‐based radiation detectors for decades. However, since the application of medical diagnoses such as gamma cameras began, bulk single crystals have been adopted as the material form of inorganic scintillators in most practical applications. Compared with ceramics or glasses, a single crystal exhibits high transmittance at its own emission wavelength, and also has high density and homogeneity, so that high detection efficiency can be achieved in a large bulk body. Many oxide scintillators exhibit a highly effective atomic number (Z_eff), non‐deliquescence, and low afterglow, compared to halide scintillators such as Tl:NaI. For this reason, extensive research has been conducted on oxide scintillators for medical and security applications [1]. In general, oxides have a larger band‐gap energy (E_g) than halides such as bromide and iodide, so that the LY tends to be relatively low [2]. However, several oxide scintillators, including well‐organized garnets [3] and silicates [4], showing LY comparable with Tl:NaI have been recently discovered. This chapter briefly describes synthesis ...