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杉田 裕; 大野 宏和; Beese, S.*; Pan, P.*; Kim, M.*; Lee, C.*; Jove-Colon, C.*; Lopez, C. M.*; Liang, S.-Y.*
Geomechanics for Energy and the Environment, 42, p.100668_1 - 100668_21, 2025/06
国際共同プロジェクトDECOVALEX-2023は、数値解析を使用してベントナイト系人工バリアの熱-水-応力(または熱-水)相互作用を研究するためのタスクDとして、幌延人工バリア性能確認試験を対象とした。このタスクは、モデル化のために、1つの実物大の原位置試験と、補完的な4つの室内試験が選択された。幌延人工バリア性能確認試験は、人工的な地下水注入と組み合わせた温度制御非等温の試験であり、加熱フェーズと冷却フェーズで構成されている。6つの研究チームが、さまざまなコンピューターコード、定式化、構成法則を使用して、熱-水-応力または熱-水(研究チームのアプローチによって異なる)数値解析を実行した。
Joung, S.*; Ji, Y.-Y.*; Choi, Y.*; Lee, E.*; Ji, W.*; 佐々木 美雪; 越智 康太郎; 眞田 幸尚
Journal of Instrumentation (Internet), 20(4), p.P04027_1 - P04027_10, 2025/04
被引用回数：0An airborne survey system named the MARK-A1 was previously developed to be mounted on an unmanned aerial vehicle for the purpose of application in contaminated areas with high dose rate levels. The MARK-A1 system consists of a CZT detector, signal processing unit, and positioning and interface units linked to a PC on the ground. The weight of the system is below 1 kg for loading on a commercial drone. In the current work, for experimental verification, field testing was conducted in a high dose rate environment near the Fukushima Daiichi Nuclear Power Plant. With the cooperation of the Japan Atomic Energy Agency, the MARK-A1 was installed on an unmanned aerial vehicle to conduct airborne surveys using two flight methods, namely a flat flight and a step flight, at various speeds. The airborne survey data were converted to gamma dose rates at a height of 1 m above the ground using a flat source model to create contamination maps. For a comparative evaluation of the airborne survey results, an in situ survey was also conducted in the survey area, and it was confirmed that the step flight method better matched the surface survey results.
Thennakoon, A.*; 横倉 涼雅*; Yang, Y.*; 梶本 亮一; 中村 充孝; 林 真弘*; 道岡 千城*; Chern, G.-W.*; Broholm, C.*; 植田 浩明*; et al.
Nature Communications (Internet), 16, p.3939_1 - 3939_13, 2025/04
被引用回数：0The pursuit of quantum spin liquid (QSL) states in condensed matter physics has drawn attention to kagome antiferromagnets (AFM) where a two-dimensional corner-sharing network of triangles frustrates conventional magnetic orders. While quantum kagome AFMs based on Cu
(
, 
) ions have been extensively studied, there is so far little work beyond copper-based systems. Here we present our bulk magnetization, specific heat and neutron scattering studies on single crystals of a new titanium fluorides Cs
RbK
Ti
F
where Ti
(
, ) ions form a modulated quantum kagome antiferromagnet that does not order magnetically down to 1.5 K. Our comprehensive map of the dynamic response function 
acquired at 1.5 K where the heat capacity is 
-linear reveals a dispersive continuum emanating from soft lines that extend along (100). The data indicate fractionalized spinon-like excitations with quasi-one-dimensional dispersion within a quasi two-dimensional spin system.
Kim, M.*; Lee, C.*; 杉田 裕; Kim, J.-S.*; Jeon, M.-K.*
Geomechanics for Energy and the Environment, 41, p.100628_1 - 100628_9, 2025/03
被引用回数：0 パーセンタイル：0.00(Energy & Fuels)この研究では、DECOVALEX-2023プロジェクトの一環として幌延の地下研究施設で実施された実規模大の人工バリア試験の数値解析を使用して、非等温二相流のモデリングに対する主要変数の選択の影響を調査した。検証済みの数値モデルを使用して、人工バリアシステム内の不均質多孔質媒体の熱-水連成挙動を解析した。支配方程式を離散化する際の2つの異なる主要変数スキームを比較したところ、結果に大きな違いがあることが明らかになった。
Rajeev, H. S.*; Hu, X.*; Chen, W.-L.*; Zhang, D.*; Chen, T.*; 古府 麻衣子*; 梶本 亮一; 中村 充孝; Chen, A. Z.*; Johnson, G. C.*; et al.
Journal of the Physical Society of Japan, 94(3), p.034602_1 - 034602_14, 2025/03
被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)Two-dimensional hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for light-emitting diode applications. In this study, by using time-of-flight neutron spectroscopy we identified and quantitatively separated the lattice vibrational and molecular rotational dynamics of two perovskites, butylammonium lead iodide (BA)
PbI
and phenethyl-ammonium lead iodide (PEA)PbI. By examining the corresponding temperature dependence, we found that the lattice vibrations, as evidenced by neutron spectra, are consistent with the lattice dynamics obtained from Raman scattering. We revealed that the rotational dynamics of organic molecules in these materials tend to suppress their photoluminescence quantum yield (PLQY) while the vibrational dynamics did not show predominant correlations with the same. Additionally, we observed photoluminescence emission peak splitting for both systems, which becomes prominent above certain critical temperatures where the suppression of PLQY begins. This study suggests that the rotational motions of polarized molecules may lead to a reduction in exciton binding energy or the breaking of degeneracy in exciton binding energy levels, enhancing non-radiative recombination rates, and consequently reducing photoluminescence yield. These findings offer a deeper understanding of fundamental interactions in 2D HOIPs and could guide the design of more efficient light-emitting materials for advanced technological applications.
experiment using a 
Cf calibration sourceLee, D. H.*; 百々 拓; 羽賀 勝洋; 原田 正英; 長谷川 勝一; 春日井 好己; 木下 秀孝; 増田 志歩; 明午 伸一郎; 酒井 健二; et al.
Nuclear Instruments and Methods in Physics Research A, 1072, p.170216_1 - 170216_6, 2025/03
被引用回数：2 パーセンタイル：94.02(Instruments & Instrumentation)JSNS investigates short-baseline neutrino oscillations using a 24-meter baseline and a 17-tonne Gd-loaded liquid scintillator target. Accurate event-reconstruction algorithms are crucial for analyzing experimental data. The algorithms undergo meticulous validation through calibration with a Cf source. This paper outlines the methodology and evaluates the reconstruction performance, focusing on neutrino interactions up to approximately 50 MeV for sterile neutrino searches. Both Cf and Michel electron events are studied to evaluate reconstruction accuracy. The analysis concludes that the uncertainty of the fiducial volume, with an appropriate correction, is much less than the requirement of JSNS requirement (10%). Furthermore, the energy resolution is measured to be 3.3 
0.1% for the Michel electron endpoint and 4.3 0.1% for the n-Gd peak in the central region.
Brumm, S.*; Gabrielli, F.*; Sanchez Espinoza, V.*; Stakhanova, A.*; Groudev, P.*; Petrova, P.*; Vryashkova, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; et al.
Annals of Nuclear Energy, 211, p.110962_1 - 110962_16, 2025/02
被引用回数：6 パーセンタイル：93.24(Nuclear Science & Technology)The completed Horizon-2020 project on "Management and Uncertainties of Severe Accidents (MUSA)" has reviewed uncertainty sources and Uncertainty Quantification methodology for the purpose of assessing Severe Accidents (SA). The key motivation of the project has been to bring the advantages of the Best Estimate Plus Uncertainty approach to the field of Severe Accident. The applications brought together a large group of participants that set out to apply uncertainty analysis (UA) within their field of SA modelling expertise, in particular reactor types, but also SA code used (ASTEC, MELCOR, etc.), uncertainty quantification tools used (DAKOTA, RAVEN, etc.), detailed accident scenarios, and in some cases SAM actions. This paper synthesizes the reactor-application work at the end of the project. Analyses of 23 partners are sorted into different categories, depending on whether their main goal is/are (i) uncertainty bands of simulation results; (ii) the understanding of dominating uncertainties in specific sub-models of the SA code; (iii) improving the understanding of specific accident scenarios, with or without the application of SAM actions; or, (iv) a demonstration of the tools used and developed, and of the capability to carry out an uncertainty analysis in the presence of the challenges faced. The partners' experiences made during the project have been evaluated and are presented as good practice recommendations. The paper ends with conclusions on the level of readiness of UA in SA modelling, on the determination of governing uncertainties, and on the analysis of SAM actions.
Lee, J.; Rossi, F.; 児玉 有; 弘中 浩太; 小泉 光生; 佐野 忠史*; 松尾 泰典*; 堀 順一*
Annals of Nuclear Energy, 211, p.111017_1 - 111017_7, 2025/02
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)Silica glass has been used as a base and host material in vitrified radioactive waste and lithium glass scintillator for neutron detection because of its superb transparency, high heat resistance, and excellent chemical inertness. Therefore, an accurate total cross section of the silica glass is important to evaluate the criticality safety for the vitrified wastes and to understand the neutron response for lithium glass scintillators accurately. In the present study, to provide the accurate total cross section in the thermal and epithermal energy range, the neutron transmission measurements were carried out by a pulsed neutron beam with the time-of-flight method at the Kyoto University Institute for Integrated Radiation and Nuclear Science - Linear Accelerator. We obtained the neutron total cross section of the silica glass in the energy region from 0.002 eV to 25 eV. The obtained results were compared and discussed with the previous results and the evaluated data.
Song, Y.*; Xu, S.*; 佐藤 駿介*; Lee, I.*; Xu, X.*; 大森 俊洋*; 長迫 実*; 川崎 卓郎; 鬼柳 亮嗣; Harjo, S.; et al.
Nature, 638, p.965 - 971, 2025/02
被引用回数：2 パーセンタイル：88.78(Multidisciplinary Sciences)In advanced applications like aerospace and space exploration, materials must balance lightness, functionality, and extreme thermal fluctuation resistance. Shape-memory alloys show promise with strength, toughness, and substantial strain recovery due to superelasticity, but maintaining low mass and effective operation at cryogenic temperatures is challenging. We hereby introduce a novel shape-memory alloy that adheres to these stringent criteria. Predominantly composed of Ti and Al with a chemical composition of Ti
Al
Cr
, this alloy 25 is characterized by a low density (4.36
10
kg/m) and a high specific strength (18510 Pa
m/kg) at room temperature, while exhibiting excellent superelasticity. The superelasticity, owing to a reversible stress-induced phase transformation from an ordered body-centered cubic parent phase to an ordered orthorhombic martensite, allows for a recoverable strain exceeding 7%. Remarkably, this functionality persists across a broad range of temperatures, from deep cryogenic 4.2 K to above room temperature, arising from an unconventional temperature dependence of transformation stresses. Below a certain threshold during cooling, the critical transformation stress inversely correlates with temperature. We interpret this behavior from the perspective of a temperature-dependent anomalous lattice instability of the parent phase. This alloy holds potential in everyday appliances requiring flexible strain accommodations, as well as components designed for extreme environmental conditions such as deep space and liquefied gases.
neutron imaging and diffraction analysis revealing spatial lithiation phase evolution in an ultra-thick graphite electrodeStrobl, M.*; Baur, M. E.*; Samothrakitis, S.*; Molamud, F.*; Zhang, X.*; Tung, P. K. M.*; Schmidt, S.*; Woracek, R.*; Lee, J.*; 鬼柳 亮嗣; et al.
Advanced Energy Materials, p.2405238_1 - 2405238_9, 2025/01
Energy-efficient, safe, and reliable Li-ion batteries (LIBs) are required for a wide range of applications. The introduction of ultra-thick graphite anodes, desired for high energy densities, meets limitations in internal electrode transport properties, leading to detrimental consequences. Yet, there is a lack of experimental tools capable of providing a complete view of local processes. Here, a multi-modal measurement approach is introduced, enabling quantitative spatio-temporal observations of Li concentrations and intercalation phases in ultra-thick graphite electrodes. Neutron imaging and diffraction concurrently provide correlated multiscale information from the scale of the cell down to the crystallographic scale. In particular, the evolving formation of the solid electrolyte interphase (SEI), observation of gradients in total lithium content, as well as in the formation of ordered Li
C
phases and trapped lithium are mapped throughout the first charge-discharge cycle of the cell. Different lithiation stages co-exist during charging and discharging; delayed lithiation and delithiation processes are observed in central regions of the electrode, while the SEI formation, potential plating, and dead lithium are predominantly found closer to the interface with the separator. The study emphasizes the potential to investigate Li-ion diffusion and the kinetics of lithiation phase formation in thick electrodes.
清水 一行*; 西村 克彦*; 松田 健二*; 布村 紀男*; 並木 孝洋*; 土屋 大樹*; 赤丸 悟士*; Lee, S.*; 都留 智仁; 髭本 亘; et al.
International Journal of Hydrogen Energy, 95, p.292 - 299, 2024/12
被引用回数：1 パーセンタイル：31.33(Chemistry, Physical)Al-0.06%Mn、Al-0.06%Cr、Al-0.02%Fe、およびAl-0.02%Ni合金(原子%)について、5
300Kの温度範囲でゼロ磁場ミューオンスピン緩和実験を行った。双極子場幅(
)の温度依存変化から、調製した合金の4つの異なるピークが明らかになった。200K未満で観測されたピークに対応するミューオン捕捉部位の原子構成は、溶質および溶質空孔対に近接する水素の捕捉エネルギーに対する第一原理計算を用いて詳細に特徴付けられた。この包括的な分析により、ミューオンピーク温度と水素捕捉エネルギーの線形相関を確立することができた。しかし、Al-Mn、Al-Cr、Al-Fe、およびAl-Ni合金では、200Kを超えると4番目のピークでこの線形関係からの大幅な逸脱が観測された。この矛盾は、4つのAl原子のうち2つが溶質元素と空孔(溶質空孔対)に置換されている四面体サイト内のミューオンと水素の異なる分布関数を考慮することで解釈できる。
勅使河原 誠; Lee, Y.*; 達本 衡輝*; Hartl, M.*; 麻生 智一; Iverson, E. B.*; 有吉 玄; 池田 裕二郎*; 長谷川 巧*
Nuclear Instruments and Methods in Physics Research B, 557, p.165534_1 - 165534_10, 2024/12
被引用回数：0 パーセンタイル：0.00(Instruments & Instrumentation)J-PARCの核破砕中性子源において、水酸化第二鉄触媒の機能性を評価するため、1MW運転時の積算ビーム出力9.4MWhの条件で、ラマン分光法を用いてパラ水素割合をその場測定した。その結果、1MW運転におけて触媒が十分に機能していることが分かった。また、触媒を通さないバイパスラインを用いて、中性子照射によるパラからオルソ水素への逆変換率を調べることを試みた。測定されたオルソ水素割合の増加は、500kW運転で積算ビーム出力2.4MWhの場合に0.44%であった。しかしながら、この結果は、冷中性子モデレータ内で引き起こされた逆変換と、バイパスされた触媒容器中の温度上昇によって発生した準静的オルソ水素のメインループへの受動的滲出との合算であることが示された。
小泉 光生; 伊藤 史哲*; Lee, J.; 弘中 浩太; 高橋 時音; 鈴木 敏*; 有川 安信*; 安部 勇輝*; Wei, T.*; 余語 覚文*; et al.
第45回日本核物質管理学会年次大会会議論文集(インターネット), 4 Pages, 2024/11
Neutron resonance transmission analysis (NRTA) is a non-destructive method applicable for measuring nuclear material using a time-of-flight (TOF) technique with a pulsed neutron source. To realize a high resolution compact NRTA system, use of a short-pulsed neutron source is essential. Laser-driven neutron sources (LDNSs) are well-suit for generating such neutron beams due to their short pulse width. The advances in laser technology will further reduce the system's size and improve practicality. In this study, we demonstrate the measurement of a neutron transmission TOF spectrum of a sample containing indium and silver using the LDNS of the Osaka University. The obtained spectrum was analyzed using the least-square nuclear-resonance fitting program, REFIT, showcasing for the first time the potential of an LDNS for nondestructive areal-density material characterization.
, 
, 
and 
mesons through their angular-dependent two-body decay modesPark, I. W.*; 佐甲 博之; 青木 和也*; Gubler, P.; Lee, S. H.*
Journal of Subatomic Particles and Cosmology (Internet), 1-2, p.100014_1 - 100014_11, 2024/11
The mass shift a spin-1 particle moving in the nuclear medium will depend on its polarization direction. To study polarization-independent mass shifts in the medium, we explore methods to isolate each polarization direction of spin-1 mesons through the angular-dependent two-body decay modes. Specifically, we study 
, 
, 
, 
and 
(
) decays. Concerning and mesons, since both particles have vacuum widths smaller than 100 MeV, they are ideal candidates for experimentally measuring chiral partners. The simultaneous observation of mass shifts of these chiral partners would provide valuable insights into the contribution of chiral symmetry breaking to the generation of hadron masses.
RhSi社本 真一; 山内 宏樹; 飯田 一樹*; 池内 和彦*; 金子 耕士; Chen, Y.-S.*; 矢野 真一郎*; Hsu, P.-T.*; Lee, M. K.*; Hall, A. E.*; et al.
Physical Review Research (Internet), 6(3), p.033303_1 - 033303_7, 2024/09
MnRhSiの磁気励起は少なくとも0.3から140meVに広がる。200Kでの非弾性散乱強度を積分することで、Mnサイト当たり約5
の磁気モーメントは、約5であることがわかった。一方で、長距離磁気秩序の磁気モーメントは4Kでわずか2.61であり、多くの部分が低温まで揺らいでいることがわかった。
小泉 光生; 伊藤 史哲*; Lee, J.; 弘中 浩太; 高橋 時音; 鈴木 敏*; 有川 安信*; 安部 勇輝*; Lan, Z.*; Wei, T.*; et al.
Scientific Reports (Internet), 14, p.21916_1 - 21916_9, 2024/09
被引用回数：2 パーセンタイル：0.00(Multidisciplinary Sciences)Laser-driven neutron sources (LDNSs) can generate strong short-pulse neutron beams, which are valuable for scientific studies and engineering applications. Neutron resonance transmission analysis (NRTA) is a nondestructive technique used for determining the areal density of each nuclide in a material sample using pulsed thermal and epithermal neutrons. Herein, we report the first successful NRTA performed using an LDNS driven by the Laser for Fast Ignition Experiment at the Institute of Laser Engineering, Osaka University. The key challenge was achieving a well-resolved resonance transmission spectrum for material analysis using an LDNS with a limited number of laser shots in the presence of strong background noise. We addressed this by employing a time-gated 
Li-glass scintillation neutron detector to measure the transmission spectra, reducing the impact of electromagnetic noise and neutron and gamma-ray flashes. Output waveforms were recorded for each laser shot and analyzed offline using a counting method. This approach yielded a spectrum with distinct resonances, which were attributed to 
In and 
Ag, as confirmed through neutron transmission simulation. The spectrum was analyzed using the least-square nuclear-resonance fitting program, REFIT, demonstrating the possibility of using an LDNS for nondestructive areal-density material characterization.
Nguyen, T.-D.*; Singh, C.*; Kim, Y. S.*; Han, J. H.*; Lee, D.-H.*; Lee, K.*; Harjo, S.; Lee, S. Y.*
Journal of Materials Research and Technology, 31, p.1547 - 1556, 2024/07
被引用回数：3 パーセンタイル：41.92(Materials Science, Multidisciplinary)This study investigates the mechanical properties of a friction-stir-welded (FSW) AA6061-T6 aluminum alloy at ultra-low temperature (ULT) of 20 K. In-situ neutron diffraction and orientation imaging microscopy were employed to compare the tensile deformation behavior of the base metal (BM) and heat-affected zone (HAZ) in the FSW aluminum plate. The results demonstrate that compared to room-temperature (RT), ULT induces a significant improvement in tensile strength and ductility in both the BM and HAZ. The enhanced mechanical properties in BM at ULT result from a more homogeneous deformation than occurs at RT. On the other hand, HAZ at ULT exhibits an even lower yield strength than at RT, but the strain hardening rate (SHR) is the most significant among the alloys, leading to a tensile strength of 346 MPa and the highest ductility of 46.8%. The lowest yield strength corresponds to the lowest-hardness zones in HAZ, caused by dissolved/coarsened precipitates during the FSW process.
Li-glass detector to gamma rays by a coincidence method伊藤 史哲*; Lee, J.; 弘中 浩太; 高橋 時音; 鈴木 敏*; 持丸 貴則*; 堀 順一*; 寺田 和司*; 小泉 光生
Nuclear Instruments and Methods in Physics Research A, 1064, p.169465_1 - 169465_9, 2024/07
被引用回数：0 パーセンタイル：0.00(Instruments & Instrumentation)The response of a gamma-ray spectrometer is generally determined by analyzing full-energy peaks. However, full-energy peaks cannot be measured easily in the case of scintillation detectors that consist of light elements, such as glass scintillators. Only a strong Compton plateau appears in the spectrum of such detectors. Therefore, Compton edgers were used to evaluate the response of these detectors. The response of a low-resolution Li-glass detector to gamma rays was measured for the first time by a coincidence method with a high-resolution LaBr
:Ce detector using cascade gamma rays (2.75 and 1.37 MeV) from a 
Na source. Coincidence gates were applied at the peaks of the spectrum of the LaBr:Ce detector at the 0.51 MeV annihilation peak, and the sum peaks of a gamma ray and a backscattered gamma ray. By analyzing the gated spectra of the Li-glass detector, the energy-dependent detector response (i.e., the output strength and its dispersion) was determined.
Rossi, F.; Lee, J.; 児玉 有; 弘中 浩太; 小泉 光生; 堀 順一*; 寺田 和司*; 佐野 忠史*
Proceedings of 65th Annual Meeting of the Institute of Nuclear Materials Management (Internet), 8 Pages, 2024/07
Various non-destructive assay techniques are being used to verify different nuclear material. However, one of the difficulties of current NDA is the measurement of highly radioactive materials. Since 2015, the JAEA has been working on the development of various active non-destructive assay techniques to address some of the current challenges in nuclear safeguards. Among the various technologies proposed, the Neutron Resonance Analysis system combines signatures from NRTA, NRCA and the newly proposed NRFNA. The combination of those techniques can provide accurate information on the small fissile content in a sample. Neutrons are generated by a pulsed neutron source and slowed down into the moderator. Neutrons are collimated using lead and borated polyethylene to reach the sample, where various neutron-induced reactions occur. n/g PSD plastic scintillators are used to measure the captured gamma rays and fission neutrons at sample location. GS20 is used to collect the transmitted neutrons downstream of the source-sample beamline. A first measurement campaign was performed using natural uranium sample. The possibility of using NRFNA to identify fissile materials within a sample was clearly demonstrated, but the detectors used were not sufficient to achieve a good n/g PSD. New PSD scintillators were introduced. A first measurement campaign was performed in 2023. The acquired data are currently being analyzed, but preliminary results show distinct fission resonance peaks of increasing intensity with varying thicknesses of the same natural uranium samples. Currently, an assembly of multiple scintillators is being investigated to provide a better signal. The new setup will be tested starting in early 2024. In this paper, we will describe in detail the NRA project development and the latest results from experimental campaign. This work is supported by MEXT under the subsidy for the "promotion for strengthening nuclear security and the like"
-phase in Al-Mg-Si alloys during aging treatmentAhmed, A.*; Uttarasak, K.*; 土屋 大樹*; Lee, S.*; 西村 克彦*; 布村 紀男*; 清水 一行*; 平山 恭介*; 戸田 裕之*; 山口 正剛; et al.
Journal of Alloys and Compounds, 988, p.174234_1 - 174234_9, 2024/06
被引用回数：10 パーセンタイル：96.31(Chemistry, Physical)本研究は、Al-Mg-Si合金における相の成長過程を形態進化の観点から明らかにすることを目的とする。本研究では、高分解能透過電子顕微鏡(HR-TEM)、集束イオンビーム(FIB)及び光学顕微鏡(OM)を用いて、相の配向関係、形状、成長過程、ミスフィット値、及び相とAlマトリックスとの界面状態を調べた。その結果、相の端にファセットが確認され、相の新しい3次元形状が2つ提案された。我々は、Mg
Si結晶の成長過程における形態変化を説明するためにミスフィットを計算し、不安定な{111}ファセットが(001)ファセットや(011)ファセットと比較して高いミスフィット値を持つことを解明した。これは、Al-Mg-Si合金の微細構造変化を予測し、所望の特性を持つ材料を設計するために重要な知見である。
