Article
Chemistry, Inorganic & Nuclear
Yuui Yokota, Takahiko Horiai, Akira Yoshikawa
Summary: In this study, charge compensation by co-doping Na+ ions at the Ca2+ sites of Ce-doped LiCaAlF6 single crystals was performed to prevent the generation of cation vacancies. As a result, improved radiation resistance and increased light yield under neutron irradiation were achieved. On the other hand, the use of Al metal as a substitute for AlF3 in Eu-doped LiCaAlF6 and Eu-doped LiSrAlF6 single crystals significantly increased the effective segregation coefficient keff of Eu2+ ions.
JOURNAL OF SOLID STATE CHEMISTRY
(2023)
Article
Physics, Applied
Yui Takizawa, Kei Kamada, Kyoung Jin Kim, Masao Yoshino, Akihiro Yamaji, Shunsuke Kurosawa, Yuui Yokota, Hiroki Sato, Satoshi Toyoda, Yuji Ohashi, Takashi Hanada, Vladimir V. Kochurikhin, Akira Yoshikawa
Summary: This study compares the suitability of the Czochralski and halide vertical Bridgman methods for growing a large-size eutectic scintillator of Tb-doped BaCl2/NaCl/KCl. The study successfully obtained 1 inch diameter eutectic bulks using the H-VB method. X-ray irradiation revealed the strongest intensity peak at approximately 550 nm. The resolution performance for radiation-imaging applications was evaluated using the grown eutectic.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Prom Kantuptim, Masaki Akatsuka, Daisuke Nakauchi, Takumi Kato, Noriaki Kawaguchi, Takayuki Yanagida
Summary: Lutetium pyrosilicate (Lu2Si2O7, LPS) single crystals were synthesized by the floating-zone method with different dopant concentration to investigate the Nd-concentration dependence on the photoluminescence (PL) and scintillation properties. The Nd-doped LPS demonstrated efficient PL and scintillation performance under X-ray irradiation.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Yuma Takebuchi, Masanori Koshimizu, Kensei Ichiba, Takumi Kato, Daisuke Nakauchi, Noriaki Kawaguchi, Takayuki Yanagida
Summary: Eulytite-type Ba3RE(PO4)(3) (RE = Y, La, and Lu) single crystals were successfully synthesized by the floating zone method, and their scintillation properties were investigated. The samples exhibited a luminescence peak at around 400 nm due to self-trapped exciton under vacuum ultraviolet and X-ray irradiation. The scintillation light yields of the Ba3RE(PO4)(3) single crystals were quantitatively clarified for the first time.
Article
Physics, Applied
Yui Takizawa, Kei Kamada, Masao Yoshino, Ryuga Yajima, Kyoung Jin Kim, Vladimir V. Kochurikhin, Akira Yoshikawa
Summary: In this study, a novel thermal neutron scintillator Eu:(LiCl)-Li-6/BaCl2 with high Li concentration was developed. The scintillator exhibited a lamellar eutectic structure and optical transparency. The cathode luminescence measurement confirmed the emission of Eu2+ in the BaCl2 phase. The scintillator showed a light yield over 20,200 photons MeV-1 under neutrons and demonstrated good potential for PSD.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Particles & Fields
Keyu Ding, Jing Liu, Yongjin Yang, Dmitry Chernyak
Summary: The light yield of a small undoped CsI crystal coupled with SiPMs at cryogenic temperature was measured, showing great potential for neutrino and low-mass dark matter detection. However, the use of cryogenic SiPMs instead of PMTs may have some drawbacks, including worse energy resolution and optical cross-talks.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Applied
Haruaki Ezawa, Yuma Takebuchi, Takumi Kato, Daisuke Nakauchi, Noriaki Kawaguchi, Takayuki Yanagida
Summary: Undoped and Tb-doped Ba3Gd(PO4)(3) single crystals were synthesized and their photoluminescence, scintillation, and thermally stimulated luminescence properties were evaluated. The Tb-doped single crystal exhibited the highest photoluminescence quantum yield and additional emission peaks in the scintillation and thermally stimulated luminescence spectra.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Kalyani, Mohit Tyagi, A. K. Singh, Sonu, G. Anil Kumar
Summary: Different concentrations of Sr co-doping were grown on Eu doped LiI single crystal scintillators to improve their performance characteristics for thermal neutron detection. The major disadvantage of these scintillators is the lack of pulse shape discrimination of neutron and gamma radiations, which can be introduced with Sr co-doping. The effects of codoping on crystal structure, electronic properties, defects, luminescence, self-absorption, and scintillation properties have been studied in detail.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Astronomy & Astrophysics
F. Calaprice, S. Copello, I Dafinei, D. D'Angelo, G. D'Imperio, G. Di Carlo, M. Diemoz, A. Di Giacinto, A. Di Ludovico, A. Ianni, M. Iannone, F. Marchegiani, A. Mariani, S. Milana, S. Nisi, F. Nuti, D. Orlandi, V Pettinacci, L. Pietrofaccia, S. Rahatlou, M. Souza, B. Suerfu, C. Tomei, C. Vignoli, M. Wada, A. Zani
Summary: New results on the radiopurity of a 3.4-kg NaI(Tl) crystal scintillator operated in the SABRE proof-of-principle detector setup show the lowest ever achieved potassium contamination and breakthrough background rate in the crystal active veto setup, dominated by Pb-210. Ongoing developments in crystal manufacture aim at further reducing background rates to levels suitable for next-generation NaI(Tl) detector arrays for the direct detection of dark matter particles.
Article
Chemistry, Physical
M. Buryi, V Babin, V Laguta, Y. Yokota, H. Sato, A. Yoshikawa, J. Pejchal, M. Nikl
Summary: Single crystals of LiCaAlF6, both undoped and doped with Eu and Na, were studied using electron paramagnetic resonance, radioluminescence, and thermally stimulated luminescence techniques. The undoped samples exposed to X-ray irradiation exhibited two hole-like charge trapping centers, while annealing in air caused the appearance of a new electron-like defect. The presence of Eu and Na dopants affected the defects distribution and incorporation in the LiCaAlF6 host, which could contribute to decreased light yield and timing characteristics.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Physics, Applied
Chen Zhao, Jiwei Ren, Lin Lei, Feiyi Liao, Kezhao Liu, Yiying Zhao
Summary: Low output power has been a limitation for micro-radioisotope batteries, but recent developments in x-ray radioluminescent batteries have shown great potential. Researchers have successfully fabricated an x-ray radioluminescent battery with near milliwatt output power and demonstrated its various potential applications.
APPLIED PHYSICS LETTERS
(2022)
Article
Crystallography
Yui Takizawa, Kei Kamada, Kyoung Jin Kim, Masao Yoshino, Akihiro Yamaji, Shunsuke Kurosawa, Yuui Yokota, Hiroki Sato, Satoshi Toyoda, Yuji Ohashi, Takashi Hanada, Vladimir. V. Kochurikhin, Akira Yoshikawa
Summary: In this study, Tb:BaCl2 and NaCl/KCl ternary eutectics were grown using quartz ampoules via the vertical Bridgman-Stockbarger method. The Tb:BaCl2 scintillator phase was found to form optical waveguides and exhibit Tb3+ emission peak under X-ray irradiation. The Tb:BaCl2/NaCl/KCl eutectics showed long photoluminescence decay times.
JOURNAL OF CRYSTAL GROWTH
(2022)
Article
Materials Science, Multidisciplinary
Kenta Igashira, Daisuke Nakauchi, Taiki Ogawa, Takumi Kato, Noriaki Kawaguchi, Takayuki Yanagida
Summary: Through the study of Eu-doped Ca2MgSi2O7 single crystals, it was found that optimal photoluminescence and scintillation properties can be achieved with dopant concentrations in the range of 1-10%. The estimated light output efficiencies are comparable at 10,400-10,700 ph/MeV, and the afterglow level is significantly reduced after Eu doping.
MATERIALS RESEARCH BULLETIN
(2021)
Article
Crystallography
Torvid Feiler, Adam A. L. Michalchuk, Vincent Schroeder, Emil List-Kratochvil, Franziska Emmerling, Biswajit Bhattacharya
Summary: Organic single crystals that combine mechanical flexibility and optical properties are rare, but small chemical modifications to the organic molecule can tune these properties independently. Incorporating a chlorine atom into the crystal backbone demonstrated a remarkable difference in optical properties and mechanical flexibility.
Article
Astronomy & Astrophysics
G. Adhikari, N. Carlin, J. J. Choi, S. Choi, A. C. Ezeribe, L. E. Franca, C. Ha, I. S. Hahn, S. J. Hollick, E. J. Jeon, J. H. Jo, H. W. Joo, W. G. Kang, M. Kauer, H. Kim, H. J. Kim, J. Kim, K. W. Kim, S. H. Kim, S. K. Kim, W. K. Kim, Y. D. Kim, Y. H. Kim, Y. J. Ko, H. J. Kwon, D. H. Lee, E. K. Lee, H. Lee, H. S. Lee, H. Y. Lee, I. S. Lee, J. Lee, J. Y. Lee, M. H. Lee, S. H. Lee, S. M. Lee, D. S. Leonard, B. B. Manzato, R. H. Maruyama, R. J. Neal, S. L. Olsen, B. J. Park, H. K. Park, H. S. Park, K. S. Park, S. D. Park, R. L. C. Pitta, H. Prihtiadi, S. J. Ra, C. Rott, K. A. Shin, A. Scarff, N. J. C. Spooner, W. G. Thompson, L. Yang, G. H. Yu
Summary: We report on the search for weakly interacting massive particle (WIMP) dark matter candidates in the COSINE-100 experiment and discuss the potential improvements for the future COSINE-200 experiment in detecting low-mass WIMPs.
Article
Materials Science, Multidisciplinary
Ichiro Kawamura, Hiroki Kawamoto, Hiromi Kimura, Hajime Komiya, Yutaka Fujimoto, Masanori Koshimizu, Go Okada, Yusuke Koba, Ryo Ogawara, Mitsuru Suda, Genichiro Wakabayashi, Takayuki Yanagida, Keisuke Asai
Summary: We have synthesized Ce3+-doped CaO-Al2O3-B2O3 glass phosphor materials with enriched B-10 and B-11 isotopes, called B-10-glass and B-11-glass, respectively, for neutron detection applications. The TL properties of these glasses were studied using X-ray, proton, and neutron irradiations. It was found that the TL intensity of neutron-irradiated B-10-glass was much greater than that of B-11-glass, and increased monotonically with neutron fluence.
MATERIALS TECHNOLOGY
(2022)
Article
Physics, Applied
Arisa Magi, Masanori Koshimizu, Atsushi Sato, Yutaka Fujimoto, Shunji Kishimoto, Takayuki Yanagida, Keisuke Asai
Summary: We developed plastic scintillators loaded with perovskite quantum dots (QDs) to enhance the detection efficiency for high-energy photons such as X-rays and gamma rays. The detection efficiency for 67.4 keV X-rays was successfully enhanced by loading, although the scintillation light yield was reduced.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Hiroki Kawamoto, Ichiro Kawamura, Hajime Komiya, Masanori Koshimizu, Yutaka Fujimoto, Keisuke Asai
Summary: Ag-doped phosphate glasses are used as radiophotoluminescence dosimeters, and this study investigates the recombination process of Ag-2(+) with trapped holes at different temperatures, revealing the mechanism of RPL disappearance.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Hajime Komiya, Ichiro Kawamura, Hiroki Kawamoto, Yutaka Fujimoto, Masanori Koshimizu, Go Okada, Yusuke Koba, Genichiro Wakabayashi, Keisuke Asai
Summary: Thermoluminescent materials enriched with B-10 and B-11 were studied for neutron detection. The TL properties of these materials were investigated after irradiation with X-rays, He ions, and thermal neutrons. The sensitivity to radiation was independent of the boron isotopes, but the TL intensity of the B-10-enriched sample was higher than that of the B-11-enriched sample after irradiation with thermal neutrons.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Biomedical
Kengo Shibuya, Haruo Saito, Hideaki Tashima, Taiga Yamaya
Summary: Positronium (Ps) lifetime imaging is a method that can extract additional biomedical information from PET. This paper presents a technique using inverse Laplace transform (ILT) to separate the lifetime components in the voxel and avoid information loss.
PHYSICS IN MEDICINE AND BIOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Toshiya Endo, Masanori Koshimizu, Yutaka Fujimoto, Keisuke Asai
Summary: In this study, PVC and PMMA films containing different black dyes were fabricated as dosimeters in radiotherapy. The experiments showed that oxidation reactions occurred in the PVC films containing Black400, and their X-ray sensitivity was significantly higher compared to other polymer films containing leuco dyes. Therefore, these PVC films containing Black400 have great potential for use as dosimeters in radiotherapy.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Hiroto Yamaguchi, Masanori Koshimizu, Hajime Komiya, Hiroki Kawamoto, Yutaka Fujimoto, Genichiro Wakabayashi, Mitsuhiro Nogami, Keitaro Hitomi, Kenichi Watanabe, Keisuke Asai
Summary: In this study, Dy3+-doped Li2O-Al2O3-B2O3 glasses were fabricated and their thermoluminescence properties after X-ray and thermal neutron irradiation were investigated. The results showed that these glasses had similar sensitivities to X-rays, and the TL intensity of the Li-6-B-11 glass was significantly higher than that of the other glasses and showed good linearity against the thermal neutron fluence.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2022)
Article
Materials Science, Multidisciplinary
Atsushi Sato, Masanori Koshimizu, Yutaka Fujimoto, Keisuke Asai
Summary: Plastic scintillators doped with 1,1,2,3,4,5-hexaphenyl-1H-silole (HPS) showed good aggregation-induced emission (AIE) behavior and improved scintillation light yield. The photoluminescence and scintillation properties of the plastic scintillators with HPS concentrations ranging from 0.10 to 10 mol% were characterized. Plastic scintillators with high concentrations of HPS exhibited high photoluminescence quantum yields and tolerance to concentration quenching due to AIE. Scintillation light yields of up to 8200 photons/MeV were achieved at HPS concentrations of 0.50 and 1.0 mol%, but decreased when the concentration exceeded 1.0 mol% due to self-absorption. The scintillation decay time constants of the first component were around 5 ns at HPS concentrations exceeding 0.5 mol%.
Article
Materials Science, Multidisciplinary
Hajime Komiya, Hiroki Kawamoto, Yutaka Fujimoto, Masanori Koshimizu, Go Okada, Yusuke Koba, Genichiro Wakabayashi, Keisuke Asai
Summary: Thermoluminescent (TL) ceramic materials for neutron detection have been developed based on Eu-doped Sr2B2O5. These materials exhibit excellent performance in photoluminescence and TL spectra, making them suitable for neutron flux measurement.
Article
Materials Science, Multidisciplinary
Hiroto Yamaguchi, Masanori Koshimizu, Hiroki Kawamoto, Yutaka Fujimoto, Genichiro Wakabayashi, Keisuke Asai
Summary: In this study, Dy3+-doped Li2O-CaO-P2O5 glasses were fabricated using 6Li or nLi isotopes and their thermoluminescent properties were investigated for neutron detection. The results showed similar sensitivities to X-rays for nLi and 6Li glasses, with TL glow peaks observed at 366 K. Furthermore, the TL intensity of the 6Li glass was significantly higher than that of the nLi glass after neutron irradiation, indicating efficient TL induction through the 6Li (n, alpha)3H reaction. Additionally, a good linear correlation was observed between thermal neutron fluence and TL intensity in the range of 1.0 x 106-1.0 x 1011 neutrons/cm2. These glasses are expected to be useful for TL dosimetry in X-rays, gamma rays, and thermal neutrons.
Article
Instruments & Instrumentation
Masanori Koshimizu, Yutaka Fujimoto, Keisuke Asai
Summary: We synthesized Ce-doped Gd3Al5-yGa(y)O(12) (GAGG) nanoparticle scintillators for efficient emission in living bodies upon X-ray irradiation. The highest photoluminescence quantum yield (QY) of 90% was achieved with the composition for Gd:Al:Ga = 3:3:2, a Ce concentration of 0.1 mol% relative to (Gd + Ce), aging at room temperature for 1 d, and a calcination temperature of 1300 degrees C. The particles had a size of 200-300 nm. The dominant emission band at around 550 nm was attributed to the 5d-4f transition of Ce3+. Nanoparticle scintillators based on Ce-doped GAGG were successfully developed, showing high photoluminescence QY and suitable size for applications in living bodies.
SENSORS AND MATERIALS
(2023)
Article
Chemistry, Physical
Yuma Takebuchi, Masanori Koshimizu, Kensei Ichiba, Takumi Kato, Daisuke Nakauchi, Noriaki Kawaguchi, Takayuki Yanagida
Summary: Eulytite-type Ba3RE(PO4)(3) (RE = Y, La, and Lu) single crystals were successfully synthesized by the floating zone method, and their scintillation properties were investigated. The samples exhibited a luminescence peak at around 400 nm due to self-trapped exciton under vacuum ultraviolet and X-ray irradiation. The scintillation light yields of the Ba3RE(PO4)(3) single crystals were quantitatively clarified for the first time.
Article
Materials Science, Multidisciplinary
Yusuke Nakabayashi, Yutaka Fujimoto, Masanori Koshimizu, Keisuke Asai
Summary: Inorganic glasses have advantages over crystals in terms of fabrication, cost, shape control, and durability. This study developed an inorganic scintillator based on phosphate glass with alkali metal and Ce3+ as the host and emission centers, respectively. The glass showed a high light yield and transparency, making it suitable for gamma and X-ray detection.
Article
Instruments & Instrumentation
M. Koshimizu, S. Kurashima, A. Kimura, M. Taguchi
Summary: By observing the scintillation time profiles of CeF3 under irradiations of pulsed beams with different LETs, we found that the initial decay was faster for higher LET, which is consistent with previous studies on other self-activated scintillators. This faster decay at higher LET can be explained by the competition between the scintillation caused by 5d-4f transition of Ce3+ ions and quenching due to the interaction between excited Ce3+ ions close to each other.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2024)
Article
Chemistry, Multidisciplinary
Atsushi Sato, Masanori Koshimizu, Yutaka Fujimoto, Shusuke Komatsuzaki, Shunji Kishimoto, Keisuke Asai
Summary: In this study, HPS crystals were synthesized to develop organic crystal scintillators based on aggregation-induced emission (AIE). The scintillation properties of HPS crystals were characterized, showing emission peak, decay time constants, and light yields comparable to conventional organic crystal scintillators. This suggests the suitability of HPS crystals as scintillation materials based on AIE behavior.
MATERIALS CHEMISTRY FRONTIERS
(2022)