Phosphors for Radiation Detectors

4Inorganic Fluoride Scintillators

Noriaki Kawaguchi, Hiromi Kimura, Daisuke Nakauchi, Takumi Kato, and Takayuki Yanagida

Nara Institute of Science and Technology, Ikoma, Japan

4.1 Introduction

Since the ZnS:Ag scintillator’s use for radiation detection experiments over 100 years ago [1], various scintillators have since been developed, including oxides, iodides, bromides, and fluorides. Figure 4.1 shows decay times and light yields of commercially available γ‐ray scintillators. The horizontal axis is the light yield, the vertical axis is the decay time, and the information on “hygroscopic,” “slightly hygroscopic,” or “non‐hygroscopic” are indicated by the symbols. From the figure, it can be seen that the fluoride scintillators are characterized by fast decay times, low hygroscopicities, and relatively lower light yields than iodide scintillators.

Figure 4.1 Decay times and light yields of commercial scintillators forγ‐ray detection [2–6].

The light yield LY (photons/MeV) and the number of emitted photons N_ph (photons) under γ‐ray excitation are expressed by the following equations [7]:

(4.1)

(4.2)

where E_γ is the γ‐ray energy absorbed by the scintillator (MeV), and β·E ...