[en] We investigated the scintillation and dosimeter properties of yttria stabilized zirconia (YSZ, Y₂O₃–ZrO₂) crystal. It showed 70–80% in-line transmittance at wavelength longer than 300 nm. Under excitations around the bandgap energy, several intense photoluminescence (PL) emission peaks appeared at 450, 550, 570 and 600 nm, and the PL decay time constants were 5.5 and 20.7 ns. In the X-ray induced scintillation spectrum, an intense emission peak around 450 nm was observed, and the scintillation decay time constants were 14.4 and 169.8 ns. After irradiations with X-rays, thermally stimulated luminescence (TSL) glow peaks appeared at 100, 200 and 450 °C. Also, after X-ray irradiations, optically stimulated luminescence (OSL) was detected around 500 nm with 650 nm stimulation.

[en] Eu-doped SrCO_3 ceramics are prepared by a spark plasma sintering (SPS) technique. In photoluminescence (PL), emissions around 615 nm due to 4f-4f transition of Eu"3"+ appear under several excitation wavelengths. The PL decay time constants are 314 ns due to the host and 400-600 μs due to Eu"3"+. The X-ray induced scintillation spectra show an intense emission peak and some small bands around 615 nm and scintillation decay time constants are 210-224 μs. In thermally stimulated luminescence (TSL) after X-ray irradiation, a strong TSL glow peak is observed in 450degC and TSL intensity increase in association with Eu concentration. (author)

[en] Au nanomaterials are known to change their properties significantly depending on their particle size. The prepared chloride glasses exhibited yellow emission (520 nm) upon UV rays (250 nm) irradiation, and the intensity of emission was found to decrease with X-ray dose. We concluded that this is because luminescent Au nanoclusters (AuNCs) of a few nanometers in size grow into Au nanoparticles (AuNPs) of a few tens of nanometers in size due to the photoreduction effect induced by irradiating X-ray, and the absorption (550 nm) attributed to the surface plasmon effect of AuNPs make decrease the AuNCs emissions. From the results of the changes of photoluminescence (PL) intensity concerning the irradiation X-ray dose, it was found that the PL intensity monotonically decreased 3000 mGy or more. This suggests that the Au-doped CsCl-BaCl₂-ZnCl₂ glass can act as an X-ray detection material in a specific dose region. (author)

[en] Ce-doped RE₃Al₅O₁₂ (Ce:REAG, RE=Tb, Dy, Ho, Er, Tm and Yb) single crystals were synthesized by the optical Floating Zone method. The transmittance is approximately 80% in all the samples, and absorptions by rare-earth ions were observed. Under X-ray irradiation, Ce:TbAG, Ce:DyAG, Ce:HoAG and Ce:TmAG exhibit scintillation signals with a broad emission band around 500–700 nm, which is attributable to the 5d–4f transitions of Ce³⁺. Several emission peaks due to F⁺ centers and 4f–4f transitions of trivalent rare-earth ions are also observed in some samples. In afterglow properties, Ce:Tb₃Al₅O₁₂ and Ce:Yb₃Al₅O₁₂ showed better afterglow levels than the other samples.

[en] Tb₃Al₅O₁₂ (TbAG) crystalline materials doped with different concentrations of Ce were prepared by the floating zone (FZ) method to evaluate their basic optical and scintillation properties. In photoluminescence (PL), a broad emission due to the 5d-4f f transition of Ce³⁺ appeared around 550 nm, and the decay time was approximately 40 ns. Under X-ray irradiation, the scintillation due to the 5d-4f transition of Ce³⁺ was also observed around 550 nm, but the decay time appeared to be much longer 376–599 ns than that of PL and it depended on the concentration of Ce. The pulse height spectroscopy analyses revealed that 3.0% Ce-doped TbAG showed the highest light yield of 30,100 ph/MeV under ¹³⁷Cs $\gamma$-ray irradiation among the samples investigated in this work.

[en] In this study, NaI transparent ceramics were synthesized by the spark plasma sintering method, also optical and scintillation properties were investigated. To evaluate the potential of the transparent ceramics, a NaI single crystal was also prepared by the vertical Bridgman-Stockbarger method. The diffuse transmittance of the transparent ceramic fabricated at 470 ℃ was equivalent to that of the single crystal. All the samples showed scintillation peaking at 320 nm due to self-trapped exciton. In addition, scintillation peaks ascribed from lattice defects were detected at 450 nm for the transparent ceramics and 540 nm for the single crystal. The scintillation decay time constants of the transparent ceramic fabricated at 440 ℃ were 5.7, 18, and 189 ns. The light yield of the transparent ceramic turned out to be 910 photons MeV⁻¹ and was two-thirds of the single crystal. (author)

[en] Ti-doped CaHfO₃ crystals were synthesized by the floating zone method equipped with xenon arc lamps, and the photoluminescence (PL) and scintillation properties are investigated. Ti-doped CaHfO₃ crystals emit strong blue photons under UV irradiation. The PL and scintillation signals are observed around 410 nm due to the charge transfer related to Ti⁴⁺. The PL and scintillation decay time constants are approximately 1 μs, which is relatively shorter than other Ti-doped materials. The scintillation light yield of Ti-doped CaHfO₃ crystals is estimated by the pulse height measurement under ¹³⁷Cs gamma-ray irradiation. The 1.0% Ti-doped sample shows the highest scintillation light yield (3400 photons/MeV) among the present samples. (author)

[en] The photoluminescence (PL) and scintillation emission spectra of β-BaB₂O₄ single crystal were studied at different temperatures from 9 to 300 K. In PL, intense emission appeared at 430 nm with a sub-peak at 365 nm, and the X-ray-induced scintillation spectrum was close to PL. When we investigated the temperature dependence of PL and scintillation, the PL intensity increased at lower temperature while the scintillation intensity decreased. This tendency can be understood to be due to thermal activation via the trapping phenomenon associated with thermally stimulated luminescence with shallow traps. (author)

[en] Pyrochlore La₂Hf₂O₇, Gd₂Hf₂O₇, and Lu₂Hf₂O₇ single crystals were successfully grown by using an optical floating zone furnace. The synthesized crystals exhibit scintillation with a broad emission peaking around 440–510 nm. The crystal quality and luminescence intensity are sufficiently high that it is applicable for pulse height spectrum measurements. Under ²⁴¹Am alpha-ray exposure, the pulse height spectrum indicates the estimated light yield of a La₂Hf₂O₇ crystal is 270 photons/MeV. (author)

[en] Li-codoped MgF₂:Tb ceramics with different Li concentrations (0.01, 0.1, 1, and 3 mol%) were prepared by the spark plasma sintering method, and photoluminescence (PL), scintillation, and dosimetric properties were investigated. Sharp peaks due to 4-4 f transitions of Tb³⁺ ion were observed in all of PL, scintillation, and thermally-stimulated luminescence (TSL). TSL glow curves confirmed that the TSL intensity was increased by Li-codoping without an increase of QY values. Especially, the TSL intensity was the highest in 1% Li-codoped MgF₂:Tb, which was approximately 2.2 times larger than that of MgF₂ doped with only Tb. Moreover, It was confirmed that the TSL responses of the 0.01, 0.1 and 1% Li-codoped MgF₂:Tb ceramics were very sensitive to irradiation dose and showed a good linearity from 0.01 to 1000 mGy.