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Your search keyword '"Yanagida, A."' showing total 640 results
Start Over Author "Yanagida, A." Publisher iop publishing
640 results on '"Yanagida, A."'

1. Scattering-free Ce:LYBO single crystals for thermal neutron detection

Author

Dongsheng Yuan, Encarnación G. Víllora, Daisuke Nakauchi, Takumi Kato, Noriaki Kawaguchi, Takayuki Yanagida, and Kiyoshi Shimamura

Subjects
scintillator, scintillation detector, thermal neutron detector, Li6Y(BO3)3, single crystal, scattering-free, Physics, QC1-999
Abstract

Ce:Li _6 Y(BO _3 ) _3 (LYBO) is a well-known candidate for thermal neutron detection with a very high Li concentration (3.06 × 10 ^22 /cm ^3 ). So far, as-grown crystals exhibit a milky appearance that compromises their performance as scintillators. Current work demonstrates, for the first time, the growth of scattering-free undoped and Ce-doped LYBO by a thermal quenching process. The origin and features of the scattering centers are investigated in detail. Furthermore, the annealing treatment for the scintillation activation is studied, finding that the reduction in oxygen vacancies is mandatory. Under thermal neutron irradiation, the annealed scattering-free Ce:LYBO single crystal achieves a record-high light yield of 6200 ph/n in a single decay with a lifetime as short as 24 ns.

Published
2024
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2. Scintillator application of CsPbBr3 quantum dots-embedded SiO2 glasses.

Author

Kato, Takumi, Shiratori, Daiki, Watanabe, Akito, Fujimoto, Yutaka, Asai, Keisuke, Nishikawa, Akihiro, Okazaki, Kai, Nakauchi, Daisuke, Kawaguchi, Noriaki, and Yanagida, Takayuki

Abstract

CsPbBr3 quantum dots-embedded SiO2 glasses were synthesized by the spark plasma sintering method as novel scintillators for γ -ray detectors. Their optical and scintillation properties were investigated to examine the scintillation performance. The X-ray diffraction patterns observed a halo peak of the SiO2 glass phase and diffraction peaks of CsPbBr3. An emission peak due to CsPbBr3 quantum dots was detected at around 515 nm in both photoluminescence (PL) and scintillation spectra. The PL and scintillation decay time curves included a component of nanosecond order, resulting from CsPbBr3 quantum dots. Under γ -ray irradiation from 137Cs, the light yield (LY) of the 0.2% CsPbBr3-embedded SiO2 glass was 150 photons MeV−1. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Comparative study of optical and dosimetric properties of Mn-doped CaF2.

Author

Kato, Takumi, Nakauchi, Daisuke, Kawaguchi, Noriaki, and Yanagida, Takayuki

Abstract

Mn-doped CaF2 has been used as a thermoluminescence detector. On the other hand, dosimetric properties of Mn-doped CaF2 transparent ceramics have not been thoroughly investigated. In this study, transparent ceramics (TC) of Mn-doped CaF2 were fabricated, and the optical and thermally stimulated luminescence (TSL) properties were investigated in comparison with Mn-doped CaF2 single crystal (SC) and opaque ceramics (Cer). The transmittance at 500 nm of the TC, SC, and Cer specimens was 58, 91, and 0%, respectively. All the specimens showed a PL peak at 490 nm with 340, 400, and 450 nm excitations, originating from d-d transitions of Mn2+ ions. The emission and excitation spectra changed with X-ray irradiation, and this phenomenon was attributed to optically stimulated luminescence. All the specimens mainly had a TSL glow peak at 300 °C. The TC specimen exhibited a higher TSL intensity than the SC and Cer specimens. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Photoluminescence and scintillation properties of Pr-doped (Lu, Y)2Si2O7 crystals.

Author

Okazaki, Kai, Nakauchi, Daisuke, Kantuptim, Prom, Kato, Takumi, Kawaguchi, Noriaki, and Yanagida, Takayuki

Abstract

Pr-doped (Lu1− x , Y x )2Si2O7 (x = 0.25, 0.5, and 0.75) crystals were synthesized by the floating zone method. Emission peaks due to 5d–4f transitions of Pr3+ were observed at 300 nm under excitation of both UV light and X-rays. Scintillation decay times of 19–22 ns were obtained, and they originated from the 5d–4f transitions of Pr3+. Afterglow levels became high from 64.7 to 541 ppm as the Y-admixed concentration increased. The light yields were estimated to be 560–700 photons MeV−1 by comparing the channels of photoabsorption peaks from the pulse height spectra of 137Cs γ -rays measured using prepared crystals and commercial Gd2SiO5 reference. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Photoluminescence, scintillation, and dosimetric properties of undoped and Tb-doped Ba3Gd(PO4)3 single crystals.

Author

Ezawa, Haruaki, Takebuchi, Yuma, Kato, Takumi, Nakauchi, Daisuke, Kawaguchi, Noriaki, and Yanagida, Takayuki

Abstract

Undoped and Tb-doped Ba3Gd(PO4)3 single crystals were synthesized by the floating zone method. Photoluminescence (PL), scintillation, and thermally stimulated luminescence (TSL) properties of the obtained single crystals were evaluated. The highest PL quantum yield value was obtained from the 5% Tb-doped single crystal. In X-ray-induced scintillation and TSL spectra, the undoped sample represented an emission peak originating from the 4f–4f transition of Gd3+ at 310 nm. The Tb-doped samples represented emission peaks originating from the 4f–4f transitions of Tb3+ and Gd3+ in the range of 310–620 nm. In TSL dose response functions, the 1% Tb-doped sample showed the highest TSL intensity, and the lower detection limit was 0.01 mGy. [ABSTRACT FROM AUTHOR]

Published
2023
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26. Surface modification of sputtered NiOx hole transport layer for CH3NH3PbI3 perovskite solar cells

Author

Masatoshi Yanagida, Tensho Nakamura, Tsukasa Yoshida, Dhruba Khadka, Yasuhiro Shirai, and Kenjiro Miyano

Subjects
General Engineering, General Physics and Astronomy
Abstract

The modification of the sputtered NiOx (x≧1)/CH3NH3PbI3 interface by 2-(3,6-dimethoxy-9H-carbazol-9-yl) ethyl] phosphonic acid (MeO-2PACz) considerably enhances the power conversion efficiency of the perovskite solar cells whose structure is ITO/NiOx/CH3NH3PbI3/[6,6]-phenyl C61 butyric acid methyl ester (PCBM)/Aluminum-doped zinc oxide (AZO)/Ag. In devices without MeO-2PACz, the internal quantum efficiency (IQE) above 450 nm increases with the increase of NiOx thickness from 4 nm to 53, although even in the thickest case, the IQE never reaches 90%. On the other hand, devices with MeO-2PACz modified NiOx show thickness insensitive IQE of ca. 90%. We propose that (1) MeO-2PACz effectively fill the pinholes in thinner NiOx and (2) it passivates the carrier trapping/recombination defects at the NiOx/perovskite interface.

Published
2023

41. Dosimetric properties of Mn2+-doped Ca2BO3Cl

Author

Wauke, Tomoaki, primary, Koide, Sohya, additional, Kawano, Naoki, additional, Kato, Takumi, additional, Fukushima, Hiroyuki, additional, Takebuchi, Yuma, additional, Okada, Go, additional, and Yanagida, Takayuki, additional

Published
2022
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43. Radio-photoluminescence phenomenon in Ag-doped Cs2O–CaO–Al2O3–P2O5 glasses

Author

Akihiro Nishikawa, Daiki Shiratori, Takumi Kato, Daisuke Nakauchi, Noriaki Kawaguchi, and Takayuki Yanagida

Subjects
General Engineering, General Physics and Astronomy
Abstract

In this study, Ag2O–Cs2O–CaO–Al2O3–P2O5 glasses with different Ag concentrations (0, 0.1, 0.3, 1.0, and 3.0 mol.%) were made by the melt-quenching method. The photoluminescence (PL) properties, the radio-photoluminescence (RPL) phenomenon, and the spatial resolution of X-ray imaging based on RPL were studied to aim for the X-ray imaging application. The RPL phenomenon was observed as an appearance of a new PL emission at around 620 nm after X-ray irradiation. According to the shape of the PL spectrum and lifetime (13.1–16.7 ns), the luminescence was confirmed to be due to Ag2+. In addition, the 3.0% Ag-doped sample had the highest emission intensity of Ag2+. From the X-ray imaging resolution test, the 3.0% Ag-doped sample showed a spatial resolution of at least 10.0 LP mm−1.

Published
2023

44. Scintillation properties of (H3NC n H2n NH3)PbBr4 (n = 8, 10, 12)

Author

Ryo Nagaoka, Naoki Kawano, Yuma Takebuchi, Hiroyuki Fukushima, Daiki Shiratori, Takumi Kato, Daisuke Nakauchi, and Takayuki Yanagida

Subjects
General Engineering, General Physics and Astronomy
Abstract

We prepared (H3NC8H16NH3)PbBr4 (1–8DIO), (H3NC10H20NH3)PbBr4 (1–10DID), and (H3NC12H24NH3)PbBr4 (1-12DIDD) crystals, and evaluated the photoluminescence (PL) and scintillation characteristics. A luminescence peak derived from free excitons was detected at around 400 nm from the crystals in the PL spectra, and the quantum yields were 8% (1-8DIO), 13% (1-10DID), and 7% (1-12DIDD). Also, scintillation light yields were determined to be 5070 photons MeV–1 for the 1-8DIO crystal, 2400 photons MeV–1 for the 1-10DID crystal, and 830 photons MeV–1 for the 1-12DIDD crystal, and they had a fast scintillation decay time of 4.8 ns (1-8DIO), 6.8 ns (1-10DID), and 3.1 ns (1-12DIDD) owing to the free exciton emissions.

Published
2023

45. Radio-photoluminescence phenomenon in Ag-doped Cs2O–CaO–Al2O3–P2O5 glasses.

Author

Nishikawa, Akihiro, Shiratori, Daiki, Kato, Takumi, Nakauchi, Daisuke, Kawaguchi, Noriaki, and Yanagida, Takayuki

Abstract

In this study, Ag2O–Cs2O–CaO–Al2O3–P2O5 glasses with different Ag concentrations (0, 0.1, 0.3, 1.0, and 3.0 mol.%) were made by the melt-quenching method. The photoluminescence (PL) properties, the radio-photoluminescence (RPL) phenomenon, and the spatial resolution of X-ray imaging based on RPL were studied to aim for the X-ray imaging application. The RPL phenomenon was observed as an appearance of a new PL emission at around 620 nm after X-ray irradiation. According to the shape of the PL spectrum and lifetime (13.1–16.7 ns), the luminescence was confirmed to be due to Ag2+. In addition, the 3.0% Ag-doped sample had the highest emission intensity of Ag2+. From the X-ray imaging resolution test, the 3.0% Ag-doped sample showed a spatial resolution of at least 10.0 LP mm−1. [ABSTRACT FROM AUTHOR]

Published
2023
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