In this review, the major achievements and research and development (R&D) trends from the last decade in the field of single crystal scintillator materials are described. Two material families are included, namely, those of halide and oxide compounds. In most cases, the host crystals are doped with Ce3+, Pr3+ or Eu2+ rare earth ions. Their spin- and parity-allowed 5d–4f transitions enable a rapid scintillation response, on the order of tens to hundreds of nanoseconds. Technological recipes, extended characterization by means of optical and magnetic spectroscopies, and theoretical studies are described. The latter provide further support to experimental results and provide a better understanding of the host electronic band structure, energy levels of specific defects, and the emission centers themselves. Applications in medical imaging and dosimetry, security measures, high-energy physics and the high-tech industry, in which X(γ)-rays or particle beams are used and monitored, are recognized as the main driving factor for R&D activities in this field.

Recent R&D Trends in Inorganic Single-Crystal Scintillator Materials for Radiation Detection

For a long time the discovery of new scintillators has been more serendipitous than driven by a deep understanding of the mechanisms at the origin of the scintillation process This situation has dramatically changed since the 1990's with an increased demand for scintillators of better performance for large particle physics experiments as well as for medical imaging It is now possible to design a scintillator for a specific purpose The bandgap can be adjusted, the traps energy levels and their concentration can be finely tuned and their influence can be damped or on the contrary enhanced by specific doping for an optimization of the performance of the scintillator Several examples are given in this paper of such crystal engineering attempts to improve the performance of crystal scintillators used in medical imaging devices An attention is also given to spectacular progress in crystal production technologies, which open new perspectives for large scale and cost effective crystal production with consistent quality

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Development of new scintillators for medical applications

This paper presents new developments in inorganic scintillators widely used for radiation detection. It addresses major emerging research topics outlining current needs for applications and material sciences issues with the overall aim to provide an up-to-date picture of the field. While the traditional forms of scintillators have been crystals and ceramics, new research on films, nanoparticles, and microstructured materials is discussed as these material forms can bring new functionality and therefore find applications in radiation detection. The last part of the contribution reports on the very recent evolutions of the most advanced theories, methods, and analyses to describe the scintillation mechanisms.

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Needs, Trends, and Advances in Inorganic Scintillators

Halide Perovskite, a Potential Scintillator for X-Ray Detection

Inorganic scintillators with high density and high light yield are of major interest for applications in medical imaging and high energy physics detectors. In this work, the optical and scintillation properties of Mg co-doped Ce:Gd 3 Al 2 Ga 3 O 12 crystals, grown using Czochralski technique, have been investigated and compared with Ce:Gd 3 Al 2 Ga 3 O 12 ones prepared with identical technology. Improvements in the timing performance of the Mg co-doped samples with respect to Ce:Gd 3 Al 2 Ga 3 O 12 ones have been measured, namely a substantial shortening of the rise time and scintillation decay components and lower afterglow were achieved. In particular, a significantly better coincidence time resolution of 233 ps FWHM, being a fundamental parameter for TOF-PET devices, has been observed in Mg co-doped crystals. The samples have also shown a good radiation tolerance under high doses of γ-rays, making them suitable candidates for applications in harsh radiation environments, such as detectors at future collider experiments.

Effect of Mg2+ ions co-doping on timing performance and radiation tolerance of Cerium doped Gd3Al2Ga3O12 crystals

Alkali earth co-doping effects on luminescence and scintillation properties of Ce doped Gd3Al2Ga3O12 scintillator

The 3 inch size Mg co-doped ${\rm Ce}:{\rm Gd}_{3} {\rm Al}_{2}{\rm Ga}_{3} {\rm O}_{12}$ single crystals were prepared by the Czochralski (Cz) method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Mg co-doping. The timing resolution measurement for a pair of $3 \times 3 \times 3\;\hbox{mm}^3$ size GAGG:Ce.Mg scintillator crystals was performed using Si-PMs.

Large Size Czochralski Growth and Scintillation Properties of $\text{Mg}^{2+}$ Co-doped $\text{Ce}:\text{Gd}_{3}\text{Ga}_{3}\text{Al}_{2}\text{O}_{12}$

Growth and scintillation properties of 3 in. diameter Ce doped Gd3Ga3Al2O12 scintillation single crystal

The Mg co-doped Y3Al5O12:Ce single crystal scintillators were prepared by micro pulling down method in a wide concentration range 0–3000 ppm of Mg co-dopant. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay, light yield to reveal the effect of Mg co-doping. The scintillation decays were accelerated by Mg co-doping. The Mg co-doped samples showed much faster decay with increasing Mg.

https://iopscience.iop.org/article/10.7567/JJAP.54.04DH17/pdf

Improvement of scintillation properties on Ce doped Y3Al5O12 scintillator by divalent cations co-doping

The Mg, Ca, Sr and Ba 200 ppm co-doped Ce:Lu3Al5O12 single crystals were prepared by micro pulling down method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of the co-doping. The scintillation decays were accelerated by both Mg and Ca co-dopants. The Mg co-doped samples showed the fastest decay and the highest light yield among the co-doped samples.

Aya Nagura

Papers

Alkali earth co-doping effects on luminescence and scintillation properties of Ce doped Gd3Al2Ga3O12 scintillator

Large Size Czochralski Growth and Scintillation Properties of $\text{Mg}^{2+}$ Co-doped $\text{Ce}:\text{Gd}_{3}\text{Ga}_{3}\text{Al}_{2}\text{O}_{12}$

Growth and scintillation properties of 3 in. diameter Ce doped Gd3Ga3Al2O12 scintillation single crystal

Improvement of scintillation properties on Ce doped Y3Al5O12 scintillator by divalent cations co-doping

Co-doping effects on luminescence and scintillation properties of Ce doped Lu3Al5O12 scintillator