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Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Sato, Kaoru*; Tsutsumi, Masaki*; Tanaka, Yoshimasa*; Ogawa, Yasunobu*; Sato, Tatsuhiko
Space Weather, 21(12), p.e2023SW003651_1 - e2023SW003651_11, 2023/12
Times Cited Count:0 Percentile:0.01(Astronomy & Astrophysics)Comprehensive understandings of their global impact on the atmosphere require whole pictures of spatio-temporal distributions of the ionization due to them. We estimate the altitude profiles of the ionization rate during the space weather event occurred in September 2017 by using the Particle and Heavy Ion Transport code System (PHITS) with input of the particle fluxes obtained by satellites. The estimates are then compared with measurements of the ionization altitude, ionization intensity, and electron density by the radars in the polar region such as the PANSY radar at Syowa Station and the EISCAT in Tromso, Norway. We conclude that the PHITS simulation results reproduce those ionizations measured by ground-based instruments with inputs of observed ionization sources by satellites within a factor of 2.
Yamashita, Susumu; Sato, Takumi; Nagae, Yuji; Kurata, Masaki; Yoshida, Hiroyuki
Journal of Nuclear Science and Technology, 60(9), p.1029 - 1045, 2023/09
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)Kondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.
Nature, 620(7976), p.965 - 970, 2023/08
Times Cited Count:6 Percentile:93.26(Multidisciplinary Sciences)no abstracts in English
Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.
Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08
Times Cited Count:2 Percentile:83.53(Astronomy & Astrophysics)Detailed -ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
Shirasu, Noriko; Sato, Takumi; Suzuki, Akihiro*; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Science and Technology, 60(6), p.697 - 714, 2023/06
Times Cited Count:1 Percentile:68.31(Nuclear Science & Technology)Interaction tests between UO and Zr were performed at precisely controlled high temperatures between 1840 and 2000 C to understand the interaction mechanism in detail. A Zr rod was inserted in a UO crucible and then heat-treated at a fixed temperature in Ar-gas flow for 10 min. After heating in the range of 1890 to 1930 C, the Zr rod was deformed to a round shape, in which the post-analysis detected the significant diffusion of U into the Zr region and the formation of a dominant -Zr(O) matrix and a small amount of U-Zr-O precipitates. The abrupt progress of liquefaction was observed in the sample heated at around 1940 C or higher. The higher oxygen concentration in the -Zr(O) matrix suppressed the liquefaction progress, due to the variation in the equilibrium state. The U-Zr-O melt formation progressed by the selective dissolution of Zr from the matrix, and the selective diffusion of U could occur via the U-Zr-O melt.
Umeda, Maki; Chudo, Hiroyuki; Imai, Masaki; Sato, Nana; Saito, Eiji
Review of Scientific Instruments, 94(6), p.063906_1 - 063906_8, 2023/06
Times Cited Count:0 Percentile:0(Instruments & Instrumentation)Pohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; Gmez-Ramos, M.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.
Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04
Times Cited Count:5 Percentile:93.15(Physics, Multidisciplinary)We report on the first proton-induced single proton- and neutron-removal reactions from the neutron deficient O nucleus with large Fermi-surface asymmetry at 100 MeV/nucleon. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively.
Li, W.*; Yamada, Shinya*; Hashimoto, Tadashi; Okumura, Takuma*; Hayakawa, Ryota*; Nitta, Kiyofumi*; Sekizawa, Oki*; Suga, Hiroki*; Uruga, Tomoya*; Ichinohe, Yuto*; et al.
Analytica Chimica Acta, 1240, p.340755_1 - 340755_9, 2023/02
Times Cited Count:4 Percentile:29.37(Chemistry, Analytical)no abstracts in English
Sato, Takumi; Nagae, Yuji; Kurata, Masaki; Quaini, A.*; Guneau, C.*
CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 79, p.102481_1 - 102481_11, 2022/12
Times Cited Count:0 Percentile:0.01(Thermodynamics)Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
Times Cited Count:1 Percentile:20.65(Astronomy & Astrophysics)We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
Futemma, Akira; Sanada, Yukihisa; Ishizaki, Azusa; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Sato, Kazuhiko*; Haginoya, Masashi*; Matsunaga, Yuki*; Kikuchi, Hikaru*; et al.
JAEA-Technology 2021-029, 132 Pages, 2022/02
By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the FDNPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter has been conducted around FDNPS. The results of the airborne radiation monitoring and the evaluation for temporal change of dose rate in the fiscal 2020 were summarized in this report. Analysis considering topographical effects was applied to the result of the airborne monitoring to improve the accuracy of conventional method. In addition, technique for discriminating gamma rays from the ground and those from the airborne Rn-progenies was also utilized to evaluate their effect on airborne radiation monitoring.
Chen, Y.*; Sato, Masahiro*; Tang, Y.*; Shiomi, Yuki*; Oyanagi, Koichi*; Masuda, Takatsugu*; Nambu, Yusuke*; Fujita, Masaki*; Saito, Eiji
Nature Communications (Internet), 12, p.5199_1 - 5199_7, 2021/08
Times Cited Count:9 Percentile:63.91(Multidisciplinary Sciences)Sato, Junya; Shiota, Kenji*; Takaoka, Masaki*
Zairyo, 70(5), p.406 - 411, 2021/05
An aluminosilicate solid is an inorganic material that has the property of immobilizing heavy metals or radionuclides in the matrix. In this study, aluminosilicates with a Si/Al molar ratio of 0.5 was synthesized from a chemical reagent in order to produce aluminosilicate solids with a low Si/Al molar ratio, which were expected to improve the immobilization of heavy metals and radionuclides contained in the matrix. The synthesized Si-Al gel with a Si/Al molar ratio of 0.5 had little impurity content and was in an amorphous phase. In addition, the compressive strength of the aluminosilicate solid produced by the synthesized Si-Al gel showed a 5 MPa or more, confirming that it can be used as a raw material for aluminosilicate solids. The aluminosilicate solid with a Si/Al molar ratio of 1.25 had a dense surface structure from the result of BSE images and had the highest compressive strength among all samples.
Nakanishi, Toshimichi*; Okuno, Mitsuru*; Yamasaki, Keiji*; Hong, W.*; Fujita, Natsuko; Nakamura, Toshio*; Horikawa, Yoshiyuki*; Sato, Eiichi*; Kimura, Haruo*; Tsutsumi, Hiroyuki*
Nagoya Daigaku Nendai Sokutei Kenkyu, 5, p.38 - 43, 2021/03
no abstracts in English
Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.
Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02
Times Cited Count:45 Percentile:96.69(Physics, Multidisciplinary)A quasifree (,) experiment was performed to study the structure of the Borromean nucleus B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for and orbitals, and a surprisingly small percentage of 9(2)% was determined for . Our finding of such a small component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B. The present work gives the smallest - or -orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of or orbitals is not a prerequisite for the occurrence of a neutron halo.
Sato, Kentaro*; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Wakimoto, Shuichi; Arai, Masatoshi*; Fujita, Masaki*
Journal of the Physical Society of Japan, 89(11), p.114703_1 - 114703_7, 2020/11
Times Cited Count:6 Percentile:49.7(Physics, Multidisciplinary)Saito, Yuji; Fujiwara, Hidenori*; Yasui, Akira*; Kadono, Toshiharu*; Sugawara, Hitoshi*; Kikuchi, Daisuke*; Sato, Hideyuki*; Suga, Shigemasa*; Yamasaki, Atsushi*; Sekiyama, Akira*; et al.
Physical Review B, 102(16), p.165152_1 - 165152_8, 2020/10
Times Cited Count:1 Percentile:5.82(Materials Science, Multidisciplinary)Sudo, Ayako; Meszaros, B.*; Poznyak, I.*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Materials, 533, p.152093_1 - 152093_8, 2020/05
Times Cited Count:4 Percentile:44.4(Materials Science, Multidisciplinary)Pshenichnikov, A.; Kurata, Masaki; Bottomley, D.; Sato, Ikken; Nagae, Yuji; Yamazaki, Saishun
Journal of Nuclear Science and Technology, 57(4), p.370 - 379, 2020/04
Times Cited Count:12 Percentile:67.54(Nuclear Science & Technology)Nakayama, Masashi; Saiga, Atsushi; Kimura, Shun; Mochizuki, Akihito; Aoyagi, Kazuhei; Ono, Hirokazu; Miyakawa, Kazuya; Takeda, Masaki; Hayano, Akira; Matsuoka, Toshiyuki; et al.
JAEA-Research 2019-013, 276 Pages, 2020/03
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The present report summarizes the research and development activities of these 3 important issues carried out during 3rd Medium to Long-term Research Phase.