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Kaminaga, Kiichi*; Hirose, Eri; 5 of others*
Journal of Radiation Research (Internet), 66(3), p.318 - 328, 2025/05
Times Cited Count：0 Percentile：0.00(Biology)
-, 
- and X-ray spectraOshima, Masumi*; Goto, Jun*; Hayakawa, Takehito*; Asai, Masato; Shinohara, Hirofumi*; Suzuki, Katsuyuki*; Shen, H.*
Journal of Nuclear Science and Technology, 10 Pages, 2025/00
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The spectrum determination method (SDM) is the method to determine radioactivities by analyzing full spectral shape of - or rays through least-squares fitting by referring to standard - and spectra. In this paper, we have newly applied the SDM to a unified spectrum composed of two spectra measured with a Ge detector and a liquid scintillation counter. By analyzing the unified spectrum, uncertainties of deduced radioactivities have been improved. We applied this method to the unified spectrum including 40 radionuclides with equal intensities, and have deduced their radioactivities correctly.
Kowatari, Munehiko*; Nakagami, Koichi*; Hijikata, Yasukazu*; Yamashita, Kazuta*; Hirai, Yuta*; Matsuzaki, Satoru*; Moritake, Takashi*; Tsuji, Tomoya; Zutz, H.*; Ketelhut, S.*; et al.
Radiation Protection Dosimetry, p.ncaf061_1 - ncaf061_9, 2025/00
Times Cited Count：0Koizumi, Mitsuo; Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Arikawa, Yasunobu*; Abe, Yuki*; Wei, T.*; Yogo, Akifumi*; et al.
Dai-45-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2024/11
Kowatari, Munehiko*; Yoshitomi, Hiroshi; Tani, Kotaro*; Tanimura, Yoshihiko; Kurihara, Osamu*
Radiation Protection Dosimetry, 200(16-18), p.1574 - 1579, 2024/11
Times Cited Count：0 Percentile：0.00(Environmental Sciences)Seito, Hajime*; Yokozuka, Eri*; Oka, Toshitaka; Kitatsuji, Yoshihiro; Nagasawa, Naotsugu*
Radiation Protection Dosimetry, 200(16-18), p.1656 - 1659, 2024/11
Times Cited Count：0 Percentile：0.00(Environmental Sciences)We have examined dosimetric characteristics of bio-inspired carbonated hydroxyapatite (CO
HAp), which is a main component of calcified tissues like tooth enamel. COHAp powder samples were exposed to gamma-ray with radiation doses ranging from 1 Gy to 1000 Gy at room temperature, and ESR spectra were measured immediately after irradiation and subsequently measured each 1 day during 90 days. The post-irradiation fading resulted in significant 20% decay of the signal amplitude, which stabilised within 7 days after irradiation, and the intensity approached a constant. The sample has good linear dose response in the experiment range of 10 Gy - 1000 Gy. Our results indicate that the COHAp materials is suitable for chemical dosimetry.
Kitamura, Yoshimasa; Oka, Toshitaka; Seito, Hajime*; Yokozuka, Eri*; Nagasawa, Naotsugu*; Kitatsuji, Yoshihiro
Radiation Protection Dosimetry, 200(16-18), p.1660 - 1665, 2024/11
Times Cited Count：0 Percentile：0.00(Environmental Sciences)In this work, we evaluated the applicability of hydroxyapatite, which is a main component of tooth enamel, as individual dosimeters that can detect from less than 1 Gy to several tens Gy. Commercially available hydroxyapatite was irradiated by 
Co gamma-ray up to 75 Gy and ESR spectrum of the irradiated sample was observed. The relationship between the intensity of produced carbonated radical and the absorbed dose shows a good linearity (
) from 0 to 75 Gy. The detection limit of this samples was estimated to be 99.7 mGy, and the radical intensity do not change for eight month from the irradiation. These results suggest that this sample can be used as a candidate of the individual dosimeter.
Arai, Yoichi; Watanabe, So; Watanabe, Masayuki; Arai, Tsuyoshi*; Katsuki, Kenta*; Agou, Tomohiro*; Fujikawa, Hisaharu*; Takeda, Keisuke*; Fukumoto, Hiroki*; Hoshina, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research B, 554, p.165448_1 - 165448_10, 2024/09
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)
Am gamma calibration field based on international standards and its conversion coefficientsTsuji, Tomoya; Yoshitomi, Hiroshi; Kowatari, Munehiko*; Tanimura, Yoshihiko
Radiation Protection Dosimetry, 200(15), p.1416 - 1424, 2024/09
Times Cited Count：1 Percentile：0.00(Environmental Sciences)Koizumi, Mitsuo; Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Arikawa, Yasunobu*; Abe, Yuki*; Lan, Z.*; Wei, T.*; et al.
Scientific Reports (Internet), 14, p.21916_1 - 21916_9, 2024/09
Times Cited Count：2 Percentile：64.46(Multidisciplinary Sciences)Sakasegawa, Hideo; Nakajima, Motoki*; Kato, Taichiro*; Nozawa, Takashi*; Ando, Masami*
Materials Today Communications (Internet), 40, p.109659_1 - 109659_8, 2024/08
Times Cited Count：1 Percentile：30.18(Materials Science, Multidisciplinary)Nanometric oxide particles play an important role in improving the creep property of Oxide Dispersion Strengthened (ODS) steels. In our previous research, we examined a microstructural feature known as prior particle boundary (PPB). PPB refers to the surface of mechanically alloyed (MA) powders before consolidation. We revealed that the ODS steel with fine PPBs produced from smaller MA powders, exhibited shorter creep rupture times, compared to that with coarse PPBs produced from larger MA powders. The size of MA powders had an impact on the creep property. In this study, we examined the shape of MA powders, which were non-spherical shapes. Such shapes have the potential to induce anisotropic creep behavior. We conducted small punch creep tests on specimens with two different orientations to study the possible anisotropy. The results revealed that the creep rupture times varied depending on the orientation of specimen, thus indicating anisotropic creep property.
Oshima, Masumi*; Goto, Jun*; Hayakawa, Takehito*; Shinohara, Hirofumi*; Suzuki, Katsuyuki*; Sano, Yuichi*; Asai, Masato; Haraga, Tomoko
Journal of Nuclear Science and Technology, 61(7), p.871 - 882, 2024/07
Times Cited Count：1 Percentile：23.64(Nuclear Science & Technology)Previously we reported a simple algorithmic method of spectral determination method (SDM), which is based on the first principle that a -ray spectrum obtained for a sample is a linear superposition of individual spectra of the radioactive nuclides included in the sample and demonstrated that the method is valid for -ray determination. Here we apply it to the spectra obtained by liquid scintillation counter (LSC). In LSC measurements quenching is generally observed and we at first developed its correction method to standard spectra. The SDM code reported in the previous investigation is used to analyze the LSC spectra. Based on the analyses done by using the measured spectra, we concluded that the SDM method is valid in the LSC spectra similarly to the -ray spectra studied in the previous investigation.
Lan, Z.*; Arikawa, Yasunobu*; Mirfayzi, S. R.*; Morace, A.*; Hayakawa, Takehito*; Sato, Hirotaka*; Kamiyama, Takashi*; Wei, T.*; Tatsumi, Yuta*; Koizumi, Mitsuo; et al.
Nature Communications (Internet), 15, p.5365_1 - 5365_7, 2024/07
Times Cited Count：5 Percentile：75.95(Multidisciplinary Sciences)Han, J.*; Uchimura, Tomohiro*; Araki, Yasufumi; Yoon, J.-Y.*; Takeuchi, Yutaro*; Yamane, Yuta*; Kanai, Shun*; Ieda, Junichi; Ohno, Hideo*; Fukami, Shunsuke*
Nature Physics, 20(7), p.1110 - 1117, 2024/07
Times Cited Count：19 Percentile：96.80(Physics, Multidisciplinary)Quantum metric and Berry curvature are two fundamental and distinct factors to describe the geometry of quantum eigenstates. While Berry curvature is known for playing crucial roles in several condensed-matter states, quantum metric, which was predicted to induce new classes of topological phenomena, has rarely been touched, particularly in an ambient circumstance. Using a topological chiral antiferromagnet MnSn adjacent to Pt, at room temperature, we successfully manipulate the quantum-metric structure of electronic states through its interplay with the nanoscale spin texture at the MnSn/Pt interface. This is manifested by a time-reversal-odd second-order Hall effect that is robust against extrinsic electron scattering, in contrast to any transport effects from the Berry curvature. We also verify the flexibility of controlling the quantum-metric structure, as the interacting spin texture can be tuned by moderate magnetic fields or by interface engineering via spin-orbit interactions. Our work paves a way for harnessing the quantum-metric structure to unveil emerging topological physics in practical environments and to build applicable nonlinear devices.
Omer, M.; Shizuma, Toshiyuki*; Hajima, Ryoichi*; Koizumi, Mitsuo
Journal of Applied Physics, 135(18), p.184903_1 - 184903_10, 2024/05
Times Cited Count：0 Percentile：0.00(Physics, Applied)
TaShizuma, Toshiyuki*; Omer, M.; Hajima, Ryoichi*; Koizumi, Mitsuo
Physical Review C, 109(5), p.054320_1 - 054320_8, 2024/05
Times Cited Count：0 Percentile：0.00(Physics, Nuclear)
NiShizuma, Toshiyuki*; Omer, M.; Hayakawa, Takehito*; Minato, Futoshi*; Matsuba, Shunya*; Miyamoto, Shuji*; Shimizu, Noritaka*; Utsuno, Yutaka
Physical Review C, 109(1), p.014302_1 - 014302_7, 2024/01
Times Cited Count：3 Percentile：84.33(Physics, Nuclear)Iwata, Takuma*; Kosa, Towa*; Nishioka, Yukimi*; Owada, Kiyotaka*; Sumida, Kazuki; Annese, E.*; Kakoki, Masaaki*; Kuroda, Kenta*; Iwasawa, Hideaki*; Arita, Masashi*; et al.
Scientific Reports (Internet), 14, p.127_1 - 127_8, 2024/01
Times Cited Count：7 Percentile：89.71(Multidisciplinary Sciences), , and X-ray spectrum analysisOshima, Masumi*; Goto, Jun*; Hayakawa, Takehito*; Asai, Masato; Kin, Tadahiro*; Shinohara, Hirofumi*
Isotope News, (790), p.19 - 23, 2023/12
When analyzing samples that contain many radionuclides at various concentrations, such as radioactive waste or fuel debris, it is difficult to apply general spectrum analysis methods and is necessary to chemically separate each nuclide before quantifying it. The chemical separation is especially essential for analysis using a liquid scintillation counter (LSC). In this report, the authors explain the newly developed spectral determination method (SDM) in which the entire spectrum is fitted to quantify radioactivity of nuclides mixed in a sample. By applying the SDM to - and X-ray spectrum measured by LSC and -ray spectrum measured by Ge detector simultaneously, the authors demonstrated that radioactivity of 40 radionuclides mixed in a sample at concentrations varying by two orders could be quantified, which is useful to simplify chemical separation process in radionuclide quantification.
Okazaki, Hiroyuki*; Idesaki, Akira*; Koshikawa, Hiroshi*; Matsumura, Daiju; Ikeda, Takashi*; Yamamoto, Shunya*; Yamaki, Tetsuya*
Journal of Physical Chemistry C, 127(49), p.23628 - 23633, 2023/12
Times Cited Count：1 Percentile：9.61(Chemistry, Physical)