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In this study, optical-guiding crystal scintillator (OCS) and bundled plates were fabricated. Considering the performance and melting point of halide scintillators and the softening point of glass, Tl:CsI was selected as the fiber core and borosilicate glass as the cladding. Thus, the fabricated OCS had a scintillator in the core and glass in the cladding. The scintillator was remelted and unidirectionally solidified to remove the voids in the OCS and form a single crystal. Consequently, the OCS served as a scintillator fiber with excellent optical-guiding performance and high sensitivity to γ- and X-rays. An OCS plate was also fabricated using bundles of OCSs with diameters of several tens of microns. The developed OCS plate is expected to be a high-resolution and high-sensitivity imaging plate because of its excellent optical-guiding performance.

Scintillation properties of a flexible optical-guiding crystal scintillator with a thallium-doped CsI (Tl:CsI) crystal and borosilicate glass as the core and cladding, respectively, are reported. The as-fabricated optical-guiding crystal scintillator exhibits a light yield of 31,000 photons MeV−1 under 662 keV γ-ray irradiation. The recrystallized sample is transparent and provides a higher light yield of 54,000 photons MeV–1, which is comparable to that of single-crystal Tl:CsI. The decay times are 400 ns (28%) and 1,350 ns (72%). This material can serve as a scintillator fiber with high sensitivity to γ- and X-rays, high light yield, and energy discrimination.

A 6LiCl/6Li2SrCl4 eutectic scintillator with a high Li concentration was developed as a novel thermal neutron scintillator. Eu2+ served as an activator for the 6Li2SrCl4 phase, and Eu-doped 6LiCl/6Li2SrCl4 eutectics were grown via the Bridgman Stockbarger method in quartz ampoules (inner diameter = 4 mm). The Eu-doped 6LiCl/6Li2SrCl4 eutectics exhibited a lamellar-type eutectic structure and optical transparency, as well as 400 nm emission due to Eu2+ 5d-4f transition. The scintillation properties of the eutectics were evaluated under gamma- and alpha-ray irradiation to demonstrate its potential as a thermal neutron scintillator.

In this study, Tl:CsI/KI/KCl eutectic scintillators were grown using the Bridgman–Stockbarger method by unidirectional solidification. The eutectic phases were uniformly distributed in the transverse direction and were slightly aligned along the growth direction. The Tl:CsI scintillator phase was grown as a matrix, which was then used for creating optical waveguides of the scintillation light. The expected Tl+ emission peak was observed at 486 nm under X-ray excitation and cathodoluminescence; this was attributed to the self-trapped exciton perturbed by TI+ in Tl:CsI. The decay time of the Tl:CsI/KI/KCl eutectic was 313 ns, and its light output was estimated to be 22,000 photons/MeV.

In this study, one-inch diameter Tl:CsI/CsCl/NaCl eutectic scintillators were grown by the Czochralski method at various pulling rates. Crystal growth conditions such as rotation, pulling rates, and crystal growth setup were analyzed. By examining the structure of the obtained eutectic, the growth orientation of the CsI phase as well as the optimum pulling speed and rotation speed were found. A transparent eutectic plate of about 3 × 5 mm was prepared from the grown sample, and scintillation properties such as light output and decay time after excitation by 662 keV gamma-rays were evaluated. The performance was compared with the Tl: CsI single crystal standard. Furthermore, a β-ray imaging test was carried out by combining the eutectic plate and an electron-multiplied charge coupling device camera, and the position resolution as an imaging device was evaluated.