[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Recent research in the field of phosphor and scintillator materials and related detectors is reviewed. After a historical introduction the fundamental issues are explained regarding the interaction of x-ray radiation with a solid state. Crucial parameters and characteristics important for the performance of these materials in applications, including the employed measurement methods, are described. Extended description of the materials currently in use or under intense study is given. Scintillation detector configurations are further briefly overviewed and selected applications are mentioned in more detail to provide an illustration.

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Scintillation detectors for x-rays

The synthesis of lanthanide-activated phosphors is pertinent to many emerging applications, ranging from high-resolution luminescence imaging to next-generation volumetric full-color display. In particular, the optical processes governed by the 4f-5d transitions of divalent and trivalent lanthanides have been the key to enabling precisely tuned color emission. The fundamental importance of lanthanide-activated phosphors for the physical and biomedical sciences has led to rapid development of novel synthetic methodologies and relevant tools that allow for probing the dynamics of energy transfer processes. Here, we review recent progress in developing methods for preparing lanthanide-activated phosphors, especially those featuring 4f-5d optical transitions. Particular attention will be devoted to two widely studied dopants, Ce3+ and Eu2+. The nature of the 4f-5d transition is examined by combining phenomenological theories with quantum mechanical calculations. An emphasis is placed on the correlation of hos...

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects.

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

The Ce-doped (LuyGd1–x)3(Gay,Al1–y)5O12 single crystals were grown by the micropulling down method. Their structure and chemical composition were checked by X-ray diffraction (XRD) and electron probe microanalysis (EPMA) techniques. Optical, luminescent, and scintillation characteristics were measured by the methods of time-resolved luminescence spectroscopy, including the light yield and scintillation decay. Balanced Gd and Ga admixture into the Lu3Al5O12 structure provided an excellent scintillator where the effect of shallow traps was suppressed, the spectrally corrected light yield value exceeded 40 000 photons/MeV, and scintillation decay was dominated by a 53 ns decay time value which is close to that of Ce3+ photoluminescence decay. This study provides an excellent example of a combinatorial approach where targeted single-crystal compositions are obtained by a flexible, time saving, and cost-effective crystal growth technique.

Composition Engineering in Cerium-Doped (Lu,Gd)3(Ga,Al)5O12 Single-Crystal Scintillators

Mg-codoped Lu3Al5O12:Ce single crystal scintillators were prepared by a micropulling down method in a wide concentration range from 0 to 3000 ppm of Mg codopant. Their structure and chemical composition were checked by X-ray diffraction and electron probe microanalysis techniques. Absorption and luminescence spectra, photoluminescence decays, and thermoluminescence glow curves were measured together with several other scintillation characteristics, namely, the scintillation decay, light yield, afterglow, and radiation damage to reveal the effect of Mg codoping. Several material characteristics manifest a beneficial effect of Mg codopant. We propose a model explaining the mechanism of material improvement which is based on the stabilization of a part of the cerium dopant in the tetravalent charge state. The stable Ce4+ center provides an additional fast radiative recombination pathway in the scintillation mechanism and efficiently competes with electron traps in garnet scintillators.

Defect Engineering in Ce-Doped Aluminum Garnet Single Crystal Scintillators

Photo- and radioluminescence characteristics of the Pr3+-doped Lu3Al5O12 single crystal are reported and compared with those of Pr-doped Y3Al5O12. With respect to the Y3Al5O12 host, lower emission quenching and better temperature stability round 300 K is obtained for the Pr3+ 5d–4f emission peaking round 308 nm and about a factor 2 higher radioluminescence intensity is observed around this temperature. The photoluminescence decay time is of about 17 ns, while the scintillation decay is dominated by the component of about 25 ns. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Alena Beitlerova

Papers

Defect Engineering in Ce-Doped Aluminum Garnet Single Crystal Scintillators

Photo‐ and radioluminescence of Pr‐doped Lu3Al5O12 single crystal

Luminescence and scintillation properties of YAG:Ce single crystal and optical ceramics

Scintillation response of Ce-doped or intrinsic scintillating crystals in the range up to 1MeV

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