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Tatebayashi, Japan

Nihon Kessho Kogaku Co. and Tohoku University | Date: 2012-08-17

An afterglow property of cesium iodide: thallium (CsI:Tl), in which CsI is a host material and doped with thallium, is improved. It is possible to improve the afterglow property of a scintillator by doping a crystal material including CsI (cesium iodide), as a host material, and thallium (Tl), as a luminescent center, with bismuth (Bi).

Fujimoto Y.,Tohoku University | Yanagida T.,Tohoku University | Kawaguchi N.,Tokuyama Corporation | Kurosawa S.,Tohoku University | And 6 more authors.
Crystal Growth and Design | Year: 2012

Single crystals of undoped and 0.5% Ce 3+-doped calcium metaborate CaB 2O 4 have been grown successfully by micropulling down (μ-PD) technique. The material can find its application in the neutron detection. After the single-phase of CaB 2O 4 was confirmed using X-ray diffraction analysis, optical and scintillation characteristics were investigated. In the transmittance spectra, Ce 3+-doped crystals showed absorption bands around 270 and 320 nm which are ascribed to the transition from 4f ground state to 5d excited state of Ce 3+. Under the 241Am 5.5 MeV α-ray excitation, strong emission peak at 370 nm because of the Ce 3+ 5d-4f transition was observed for Ce 3+-doped crystal, while the undoped crystal showed broad intrinsic emission band around 300-400 nm which is caused by the lattice defects in the host crystal. The absolute light yield was calculated to be about 2200 photons per neutron under 252Cf neutron irradiation. © 2011 American Chemical Society.

Nihon Kessho Kogaku Co. | Date: 2011-06-30

A fluorite with excellent laser durability is provided by devising a heat-treatment method for CaF

Nihon Kessho Kogaku Co. | Date: 2013-11-07

A fluorite having all the more excellent laser durability compared to a conventional fluorite is provided. A fluorite is proposed, in which the standard deviation of the surface areas of the Voronoi regions in a diagram from a Voronoi decomposition of the distribution of etch-pits in the (111) plane is 6,000 m

Yanagida T.,Tohoku University | Fujimoto Y.,Tohoku University | Kawaguchi N.,Tohoku University | Kawaguchi N.,Tokuyama Corporation | And 6 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

The crystals of 1 mol% Ce-doped LuLiF4 (Ce:LLF) grown by the micro-pulling down (μ-PD) method and 1 mol% Ce-doped LuScBO3 (Ce:LSBO) grown by the conventional Czochralski (Cz) method were examined for their scintillation properties. Ce:LLF and Ce:LSBO demonstrated ∼80% transparency at wavelengths longer than 300 and 400 nm, respectively. When excited by 241Am α-ray to obtain radioactive luminescence spectra, Ce3 5d4f emission peaks were detected at around 320 nm for Ce:LLF and at around 380 nm for Ce:LSBO. In Ce:LSBO, the host luminescence was also observed at 260 nm. By recording pulse height spectra under γ-ray irradiation, the absolute light yield of Ce:LLF and Ce:LSBO was measured to be 3600±400 and 4200±400 ph/MeV, respectively. Decay time kinetics was also investigated using a pulse X-ray equipped streak camera system. The main component of Ce:LLF was ∼320 ns and that of Ce:LSBO was ∼31 ns. In addition, the light yield non-proportionality and energy resolution against the γ-ray energy were evaluated. © 2010 Elsevier B.V.

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