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杉原 健太; 小野寺 直幸*; 井戸村 泰宏; Sitompul, Y.; 山下 晋
Journal of Computational Physics, 547, p.114534_1 - 114534_25, 2026/02
We propose a new gas-liquid two-phase fluid calculation method that improves computational efficiency compared with the conventional incompressible method (Incompressible). The methods are called the semi-implicit compressible method (SI-C) and the semi-implicit weakly compressible method (SI-WC). SI-C improves the convergence of the iterative solver by computing the pressure Poisson-type equation derived from the compressible fluid equation. In SI-WC, the number of iterations can be further reduced by computing a weakly compressible Poisson-type equation that uses an artificial sound speed controlled by the Mach number. The validity of the proposed method was verified by dam breaking problems and bubbly flow analysis, and comparative verification showed that compared to Incompressible, SI-C and SI-WC accelerate the pressure Poisson-type equation solver by a factor of two and four, respectively, while achieving almost the same solutions.
underwater radiation monitoring detectorJi, W.*; Lee, E.*; Ji, Y.-Y.*; 越智 康太郎; 吉村 和也; 舟木 泰智; 眞田 幸尚
Nuclear Engineering and Technology, 58(2), p.103933_1 - 103933_6, 2026/02
汚染予測地点の河川や貯水池の堆積物中の
Cs放射能濃度を推定するために、水中放射線in-situ検出器MARK-U1(Monitoring of Ambient Radiation of KAERI - Underwater)の性能を検証することを目的とした。さらに、高純度ゲルマニウム(HPGe)半導体検出器を用いて放射能を測定するため、コアサンプルを採取した。放射能を推定するために、測定されたスペクトルと試料中のCs放射能を比較して換算係数を導き出した。モンテカルロN粒子(MCNP)シミュレーションを実施し、in-situ測定に有効な線源形状を決定した。シミュレーション結果は、31.62%の偏差で、現場のMARK-U1モニタリング結果とよく相関した。これらの結果は、in-situ検出器の性能を検証するものである。したがって、この装置は、試料採取を必要とせず、in-situモニタリングによって水底堆積物中のCs放射能濃度を推定するために使用することができる。
RhZhang, J. Z.*; Chen, Z. Q.*; Qu, T.*; Wang, Y. K.*; Li, Z. H.*; Orlandi, R.; 他62名*
Physics Letters B, 873, p.140144_1 - 140144_9, 2026/02
At the RIKEN, 
-delayed 
-ray spectroscopy studies were conducted on 
Rh and 
Rh, resulting in the world's first successful identification of a 1/2
isomer in these isotope, extending the energy difference between the 9/2
and 1/2 states up to neutron number 
=74. Comparison of the new results with state-of-the-art calculations suggests that triaxial deformation plays a significant role in the evolution of the energy difference, indicating a shape transition from axially symmetric to triaxial deformation within the Rh isotopic series. These findings provide new insights into the structure of neutron-rich nuclei in the atomic number 
region, elucidating the interplay between triaxial deformation and shell evolution.
Dong, F.*; Xiao, Y.*; Chen, S.*; 出町 和之*; 高屋 茂; 吉川 雅紀
Advanced Engineering Informatics, 69(Part D), p.104094_1 - 104094_23, 2026/01
Ensuring safe and stable industrial plant operations requires accurate and timely fault diagnosis from multivariate time-series (MTS) sensor data. Conventional methods struggle with the complexity, high dimensionality, and limited feature extraction. To address this, we propose a novel end-to-end fault diagnosis framework that enhances class separability by leveraging instance-wise global and timestamp-wise local views of MTS representations. The dataset is augmented from the dual-view, and a complementary contrastive loss function captures both global and local contextual information. Unlike previous representation learning approaches, the diagnosis model's backbone and classifier are jointly optimized in an end-to-end scheme, ensuring aligned representations with the classification objective. Experimental results on simulated nuclear power plant fault datasets demonstrate the framework's effectiveness and robustness.
Qin, T. Y.*; Hu, F. F.*; 徐 平光; Zhang, R.*; Su, Y. H.; Ao, N.*; Li, Z. W.*; 篠原 武尚; 菖蒲 敬久; Wu, S. C.*
International Journal of Fatigue, 202, p.109233_1 - 109233_16, 2026/01
The surface induction-hardened S38C medium carbon steel shows a good balance of strength and toughness, but complicates the evaluation of fatigue resistance, mainly because of gradient residual stress (RS) and grains. An integrated fatigue resistance assessment (AIFA) framework was proposed to consider the residual stress relief under stochastic loads. To this end, quasi-in situ neutron diffraction and Bragg-edge imaging were combined to probe the evolution of residual stress during crack propagation. Firstly, a rigid-flexible coupled vehicle dynamics model was adopted to obtain the time-domain variable amplitude loading spectrum. Then, Fortran subroutines were developed to assign these data into full-scale S38C axle model, and the remaining life was predicted using the damage tolerance approach. The results demonstrate that crack propagation would accelerate when residual stress is considered in the case of the crack depth exceeding 3.0 mm. It is, for the first time, found that 15 mm- and 5 mm-thickness fan-shaped specimens can retain the axial and hoop residual strain in terms of diffraction angle variation, respectively, for full-scale structural S38C steel axles. In the absence of RS, the remaining life of the axle decreases sharply from 624,800 to 51,300 km as the crack depth increases from 3.0 to 16 mm. Compared with the standard method under constant amplitude loading without residual stress relief, the present AIFA method provides the more accurate but conservative fatigue life prediction.
Villagrasa, C.*; Baiocco, G.*; Chaoui, Z.-E.-A.*; Dingfelder, M.*; Incerti, S.*; Kundr
t, P.*; Kyriakou, I.*; 松谷 悠佑; 甲斐 健師; Parisi, A.*; et al.
PLOS ONE (Internet), 21(1), p.e0340500_1 - e0340500_22, 2026/01
電離放射線被ばくの生物学的影響を理解するために重要なナノ線量測定は、分子スケールでの原子相互作用を再現するMonte Carlo Track Structure (MCTS)コードにより評価可能である。数十年にわたり独立して開発された様々なMCTSコードは、生物組織の主成分である液体水中の電子線の相互作用について、異なる物理モデルと断面積データセットを使用してきた。本研究では、様々なMCTSコード内の相互作用断面積の違いによって生じるナノ線量測定計算の不確実性を評価した。7つのMCTSコード(Geant4-DNA, PARTRAC, PHITS, MCwater、およびPTra)の計算結果から、平均電離数や2回以上の電離が起こる確率などの分子スケールの物理量に大きな相違があることが明らかとなった。最も大きな相違が確認されたのは低エネルギー電子で、相互作用断面積の寄与が不確実性の主要因であることがわかった。本成果より、断面積の相違が複雑なDNA損傷などの生物学的影響に無視できない影響を与えることが浮き彫りになった。
Chong, Y.*; 都留 智仁; Gholizadeh, R.*; Minor, A. M.*; 辻 伸泰*
Acta Materialia, 301, p.121523_1 - 121523_12, 2025/12
六方最密充填(HCP)チタン合金は、非対称なHCP結晶構造のため本質的に独立した滑り系が少ないため、大きな延性を達成するには双晶形成が不可欠である。一般に双晶形成は原理的には微量の格子間酸素によって抑制され、チタンの延性が大幅に低下することが知られているが、その根本的なメカニズムは議論の余地がある。本研究では、Ti-O合金の双晶形成/双晶回復挙動に関する体系的なマルチスケール研究を報告し、格子間酸素が双晶形成を阻害する要因を検討した。アトムプローブトモグラフィーを使用して、酸素原子が{10
2}
引張双晶境界と{11
2}圧縮双晶境界の両方に偏析することを初めて明らかにした。また、第一原理計算によって、酸素シャッフルメカニズムによる双晶境界への酸素原子の強いピン止め効果が示され、これにより異なる温度でのTi-O合金の双晶境界の特異な移動形態を説明することに成功した。これらの実験と計算による研究から得られた知見は、格子間不純物含有量の変動に対する許容度を高めたチタン合金の設計の根拠となり、この高強度で軽量な材料のより広範な使用に大きな意味をもたらす。
Ji, Y.-Y.*; Joung, S.*; Ji, W.*; 越智 康太郎; 佐々木 美雪; 眞田 幸尚
Journal of Radiological Protection, 45(4), p.042501_1 - 042501_11, 2025/12
本研究では、LaBr
(Ce)検出器を用いた韓国原子力研究院の無人航空機搭載型ガンマ線スペクトロメトリーシステムの開発と実地検証について報告する。FDNPP付近における日本原子力研究開発機構との共同調査では、高度に基づく減衰補正を適用後、信頼性の高い線量率推定が得られたが、傾斜地では差異が生じた。緊急対応用途における精度向上のため、地形データの組み込みが推奨される。
Marium, M.*; 青木 健太郎*; He, Y.*; 山本 勝宏*; Suwansoontorn, A.*; 生田 聖也*; 原 光生*; 永野 修作*; 長尾 祐樹*; 西川 慶*; et al.
ACS Applied Energy Materials (Internet), 8(22), p.16589 - 16600, 2025/11
High C-rate capability and energy-density stability are crucial for advanced lithium-ion batteries (LIBs). However, these two characteristics typically conflict in conventional systems. Herein, a lyotropic polymer liquid crystal (LPLC)-based coating was applied to the surface of LiNi
Co
Mn
O
(NCM523) cathode to construct a highly ion-conductive artificial cathode electrolyte interface (CEI) layer, aiming to supersede traditional CEIs for LIBs. The coating material, composed of an amphiphilic lithium-substituted alkyl-sulfonated polyimide (ASPI-Li) and an appropriate amount of organic liquid electrolyte, forms nanoscale ion conduction channels that act as an artificial CEI layer, providing enhanced local Li-ion activity at the NCM523 surface. The ion-conduction channels, regulated by the layered structure within the ASPI-Li coating layer, significantly accelerated ion-diffusion kinetics at the electrode/electrolyte interface, thereby delivering superior C-rate capability at ambient temperatures compared with conventional LIB systems. This work, guided by molecular design, provides insights into the development of next-generation artificial CEI layers for efficient and sustainable energy-storage systems.
篠原 佑也*; 岩下 拓哉*; 中西 真大*; Liu, Y.*; Cooper, V. R.*; 古府 麻衣子*; 楡井 真実; Dmowski, W.*; Hickner, M. A.*; 江上 毅*
Journal of Physical Chemistry B, 129(47), p.12330 - 12337, 2025/11
Enhancing proton transport in polymer electrolytes is crucial for advancing next-generation solid-state batteries, yet our understanding of proton conductivity in nonaqueous environments remains limited due to a lack of atomic-scale insights. In this study, we investigated the atomic-scale dynamics of 1,2,3-triazole, a small molecule capable of dynamic hydrogen bonding, as a model system for proton hopping in nonaqueous environments. Using the real-space correlation function determined by the double Fourier transformation of inelastic neutron scattering spectra, we identified that the self-motion of protons and intermolecular dynamics occur on comparable time scales. Furthermore, we observed that the activation energy associated with the intermolecular dynamics matches the energy barrier for molecular rotations determined through Density Functional Theory calculations. These findings underscore the importance of controlling molecular dynamics at the atomic scale to control proton transport. Additionally, we demonstrated that intermolecular dynamics in systems involving protons can be studied using inelastic neutron scattering even without deuteration, thereby providing a broader avenue for studying atomic-scale dynamics in soft matter systems.
Yang, Y.*; 平 義隆*; 静間 俊行*; Omer, M.
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.194 - 196, 2025/11
Highly polarized MeV gamma-rays, produced by Laser Compton Scattered (LCS) of a polarized laser with an electron beam, offer a unique probe for basic and applied physics research. As the polarization characteristics of these gamma-rays vary with the position of the beam cross section, it is essential to understand the polarization properties when using polarized gamma-rays. However, detailed measurements of the two-dimensional spatial polarization distribution have not yet been conducted. In the UVSOR synchrotron facility, a polarimeter was developed to measure the spatial polarization distribution of linearly polarized gamma-rays. The polarimeter is based on asymmetry measurements of the Compton scattering cross section. In this conference, we will report on measurement results of the spatial polarization distribution of linearly and circularly polarized LCS gamma-rays. The polarization axis of the polarized gamma-rays was clearly measured to vary with scattering and azimuth angle. In the near future, we plan to use the developed polarimeter to also measure the spatial polarization distribution of gamma-rays generated by an axially symmetric polarized laser.
Jeong, S. G.*; Kwon, J.*; Kim, E. S.*; Prasad, K.*; Harjo, S.; Gong, W.; 川崎 卓郎; Estrin, Y.*; Bouaziz, O.*; Hong, S. I.*; et al.
Materials Science & Engineering A, 942, p.148712_1 - 148712_11, 2025/10
The cellular structure plays a key role in determining the mechanical properties of metal additive manufacturing (MAM) components. This study presents in situ neutron diffraction and dislocation density-based modeling for a CoCrFeMnNi high-entropy alloy (HEA) made via directed energy deposition (DED). A constitutive model based on the Kocks-Mecking-Estrin framework was used to represent the cellular structure. Parametric analysis showed lower dislocation accumulation and annihilation rates in the as-built sample (with cellular structure) than in the heat-treated one. These differences are linked to dislocation forest networks and local stacking fault energy variations. Dislocation density across cell interiors and walls was also compared with deformation-induced dislocation cells.
Moon, J. Y.*; 伊藤 由太; 他13名*
Journal of the Korean Physical Society, 87(5), p.640 - 648, 2025/09
被引用回数：2 パーセンタイル：44.93(Physics, Multidisciplinary)A new large-scale heavy-ion accelerator complex, RAON (Rare isotope Accelerator complex for ON-line experiments), in Korea has implemented the state-of-art device, multi-reflection time-of-flight mass spectrometer (MRTOF-MS) for the mass spectrometry of the exotic nuclei. Using the multi-reflections of ions between a pair of grid-free mirror electrodes and therefore extending the fly length, it can achieve the incredibly high mass resolving power of within a short measurement time of 
10 ms, providing the nuclear mass of the exotic nuclei with a high-precision level of sub-ppm. The device is coupled to one of the beamlines in the ISOL experimental hall, ready for participating in the longstanding topics of nuclear structure in the outskirts of the nuclear chart and nucleosynthesis of heavy elements in explosive astrophysical environments. The exclusively high mass resolving power is also advantageous for reducing the isobaric contaminants that rare isotope ion beam facilities suffer from. In this paper, we present a summary of the construction and current performance of the RAON MRTOF-MS.
松谷 悠佑; 嵯峨 涼*; Wang, Y.*; 佐藤 達彦
Medical Physics, 52(10), p.e70040_1 - e70040_14, 2025/09
放射線誘発微小核(micronuclei, MN)は染色体断片であり、近年、比較的早期に検出可能な染色体異常の定量的指標として使用されている。近年、MN形成を評価する技術は注目を集めているものの、MNの意義とそれに伴う細胞応答は未だ解明されていない。本研究では、被ばく後の細胞生存率を予測可能なintegrated microdosimetric-kinetic(IMK)モデルを拡張し、MN頻度を推定する生物物理学的モデルを提示し、MN形成に伴う細胞応答を理論的に検討した。本モデルは、修復不全による致死損傷からのMN形成確率を導入することで、線エネルギー付与や線量率に依存したMN形成頻度の予測に成功した。また、同モデルを使用した解析により、同一照射条件下では、細胞生存率とMN頻度に対する生物学的効果比は同等であることが確認された。本成果は、MNが放射線治療と放射線防護の双方において、被ばく後早期における治療効果と組織学的損傷を定量的に評価するために有用であることを示唆している。
Che, G.*; Tang, X.*; Liu, J.*; Lang, P.*; Fei, Y.*; Yang, X.*; Wang, Y.*; Gao, D.*; Wang, X.*; Ju, J.*; et al.
Nano Letters, 25(39), p.14467 - 14472, 2025/09
機械化学的ラジカル重合は、溶媒消費量の削減と不溶性モノマーへの適応性により、ポリマー合成において独自の利点を有する。しかしながら、反応中に生成ポリマーが制御不能に分解するという課題があり、精密な制御性を備えた新たな合成戦略の開発が求められている。本研究では、最大30GPaの高静圧を適用することで、1,3,5-トリフルオロベンゼンが共役
結合を切断するラジカル重合を起こし、高選択性でカーボンナノスレッド(ポリマーI多形体)を形成することを発見した。閾値圧力における結晶構造と結合経路の計算エネルギー障壁に基づき、ベンゼン環が1-2ラジカル重合経路で反応すると結論付けた。本研究は、極めて安定な芳香族化合物に対しても固相ラジカル重合を開始する堅牢な手法として高圧が有効であることを示し、高選択性を持つ炭素系高分子材料の合成に向けた新たな知見を提供する。
AuFu, X. Y.*; Liu, Z.*; Andreyev, A. N.; 他40名*
Chinese Physics C, 49(8), p.084004_1 - 084004_6, 2025/08
Delayed -ray spectroscopy of Au was performed at Argonne. A new isomer at 1504.2(4)~keV with a 630(80)~ns half-life was identified using - coincidences. It decays via a 294.8(3)~keV transition. Weisskopf estimates suggest this transition is likely E1, M1, E2, or M2. Possible configurations for this isomer are discussed using configuration-constrained potential energy surface calculations.
Zhao, X.*; Zhang, Z.*; 服部 高典; Wang, J.*; Li, L.*; Jia, Y.*; Li, W.*; Xue, J.*; Fan, X.*; Song, R.*; et al.
Nature Communications (Internet), 16, p.7713_1 - 7713_8, 2025/08
被引用回数：0 パーセンタイル：55.06熱効果は、固体状態の冷凍技術の一つの解決策の基盤を成すもので、通常は固体状態の相転移付近で発生し、冷凍温度範囲が限定されている。ここでは、前例のない概念である「全温度帯バロカロリック効果」を導入し実現する。すなわち、KPF
において77.5Kから300Kの極めて広い温度範囲(潜在的に4Kまで)で観測される顕著なバカカロリック効果である。この温度範囲は、一般的な室温、液体窒素、液体水素、液体ヘリウムの冷却領域をカバーしている。直接測定されたバーカロリック断熱温度変化は、250MPaの圧力を解放した際に、室温で12K、77.5Kで2.5Kに達する。この効果は、圧力依存性の中性子粉末回折、ラマン散乱解析、第一原理計算により示されるように、菱面体高圧相への持続的な相転移に起因する。構造的不安定性を考慮した熱力学的エネルギーランドスケープを記述する。この独自の全温度帯バロカロリック効果は、従来の多段式シナリオを超えた、高度に適用可能な固体状態冷凍技術への新たなアプローチを提供する。
structures from a coupled-channel perspectiveZhang, Y.*; Song, Q.-F.*; L
, Q.-F.*; 永廣 秀子*; 保坂 淳
Physical Review D, 112(3), p.034035_1 - 034035_11, 2025/08
結合チャネルのアプローチで低励起の構造を系統的に調べた結果を報告する。
平 義隆*; Yang, Y.*; 静間 俊行*; Omer, M.
Physical Review Research (Internet), 7(3), p.033130_1 - 033130_17, 2025/08
Highly polarized gamma rays with linear or circular polarization are essential light sources for nuclear and particle physics experiments, astronomical detector evaluations, and relativistic electron beam diagnostics. In this study, we demonstrate gamma-ray generation via Compton scattering with unique polarization states, termed axially symmetric polarization. To investigate this, we developed a polarimeter for Compton gamma-ray sources to measure their two-dimensional polarization distribution. We found two methods to generate gamma rays whose polarization axis follows the azimuthal direction. The first method exploits the inherent azimuthal polarization of gamma rays produced using a circularly polarized laser. In this configuration, the gamma rays along the central axis are circularly polarized, while the linear polarization components in the outer region of the beam cross section are aligned azimuthally. The second method utilizes azimuthal polarization that arises in the outer region of the beam due to the incoherent superposition of multiple linearly polarized gamma rays with varying polarization axes, generated by an axially symmetric polarized laser. Additionally, our calculations indicate the feasibility of generating gamma rays with polarization axes oriented along the radial direction. This radial polarization, observed near the beam axis, results from the incoherent superposition of second harmonic gamma rays produced through nonlinear interactions induced by an intense axially symmetric polarized laser.
竹内 祐太朗*; 佐藤 佑磨*; 山根 結太*; Yoon, J.-Y.*; 菅野 之矩*; 内村 友宏*; De Zoysa, K. V.*; Han, J.*; 金井 駿*; 家田 淳一; et al.
Science, 389(6762), p.830 - 834, 2025/08
被引用回数：0 パーセンタイル：77.58Electric current driving of antiferromagnetic states at radio or higher frequencies remains challenging to achieve. In this study, we report all-electrical, gigahertz-range coherent driving of chiral antiferromagnet manganese-tin (MnSn) nanodot samples. High coherence in multiple trials and threshold current insensitive to pulse width, in contrast to results observed with ferromagnets, were achieved in subnanosecond range, allowing 1000/1000 switching by 0.1-nanosecond pulses at zero field. These features are attributed to the inertial nature of antiferromagnetic excitations. Our study highlights the potential of antiferromagnetic spintronics to combine high speed and high efficiency in magnetic device operations.
