To date, ³He gas has been commonly used to detect thermal neutrons because of their high chemical stability and low sensitivity to γ-rays, owing to their low density and large neutron capture cross-section. However, the depletion of ³He gas prompts the development of a new solid scintillator for thermal neutron detection to replace ³He gas detectors. Solid scintillators containing ⁶Li are commonly used to detect thermal neutrons. However, they are currently used in single crystals only, and their ⁶Li concentration is defined by their chemical composition. In this study, ⁶Li-containing eutectic scintillators were developed. CeCl₃ was selected as the scintillator phase because of its low density (3.9 g/cm³); high light yield (30,000 photons/MeV); and fast decay time with four components of 4.4 ns (6.6%), 23.2 ns (69.6%), 70 ns (7.5%) and >10 μs (16.3%), owing to the Ce³⁺ 5d-4f emission peak at approximately 360 nm. Crystals of the CeCl₃, LiCl and CaCl₂ ternary eutectic were fabricated by the vertical Bridgman technique. The grown eutectic crystals exhibited Ce³⁺ 5d-4f emission with a peak at 360 nm. The light yield was 18,000 photons/neutron, and the decay time was 10.5 ns (27.7%) and 40.1 ns (72.3%). Therefore, this work demonstrates optimization by combining a scintillator phase and Li-rich matrix phase for high Li content, fast timing, high light yield and low density.

In recent years, thermal neutron detection using scintillators has been used in a wide range of fields. Thus, the development of scintillators with a higher light yield, faster decay, and higher sensitivity for thermal neutrons is required. In this study, K₂CeCl₅/⁶LiCl and CeCl₃/SrCl₂/⁶LiCl were developed as novel eutectic scintillators for thermal neutron detection. LiCl was selected as the neutron capture phase and K₂CeCl₅ and CeCl₃ were used as the scintillator phases. The eutectics of K₂CeCl₅/⁶LiCl and CeCl₃/SrCl₂/⁶LiCl were prepared using the Vertical Bridgman method and the phases were identified by scanning electron microscopy and powder X-ray diffraction measurements. The results of radioluminescence measurements under Ag source X-ray tube irradiation confirmed that the 5d-4f emission derived from Ce³⁺. The cathodoluminescence spectra and thermal neutron responses of the prepared eutectics were measured to evaluate their optical properties.

We report the development of bundled optical-guiding crystal scintillators (OCSs) with ultrafine and uniform scintillator cores (~12 μm) for high-resolution X-ray imaging. Conventional OCS fabrication using iodide scintillators often suffers from iodine volatilization, bubble formation, and core discontinuities, which limit structural uniformity and device reliability. To address these limitations, a hollow-fiber-based fabrication strategy was introduced. Hollow glass fibers were first bundled and drawn without scintillator materials, followed by capillary infiltration of a Tl-doped Cs₃Cu₂I₅ (Tl: CCI) melt. This approach enabled the stable formation of densely packed bundled OCS structures with uniform core diameters of 10–12 μm while suppressing volatilization-induced defects. Radioluminescence measurements confirmed a broad emission peak at ~442 nm, consistent with Tl:CCI scintillation. X-ray imaging experiments demonstrated superior spatial resolution and image contrast compared with a commercial CsI:Tl columnar scintillator. The bundled OCS exhibited an average contrast transfer function (CTF) of 30.7% at ~10 lp/mm, exceeding the reference value. These results demonstrate that the hollow-fiber architecture provides an effective route toward scalable ultrafine-core scintillators and highlight the potential of Tl:CCI-filled OCSs for next-generation high-resolution X-ray imaging.