Multiwire-type two-dimensional neutron detector with high pressure for J-PARC MLF BL17 neutron reflectometer

藤 健太郎; 中村 龍也; 坂佐井 馨; 山岸 秀志*

JPS Conference Proceedings (Internet), 45, p.011201_1 - 011201_8, 2026/06

https://doi.org/10.7566/JPSCP.45.011201

Neutron reflectometry experiments using a gaseous two-dimensional neutron detector system with multiwire elements have been performed at the MLF BL17 Sharaku at the J-PARC Center. We have developed a two-dimensional neutron detector for BL17 utilizing a multiwire-type detector element known for its reliability. This system has been operating reliably for over 10 years without major maintenance. Initially, the detector used a low-pressure fill gas (0.27 MPa) due to a helium-3 shortage. To improve sensitivity, a new high-pressure detector (0.7 MPa) was developed, featuring a robust pressure vessel and updated signal processing circuits. Pulsed neutron irradiation tests showed that the new detector's sensitivity at the TOF peak (12.4 ms, neutron energy 11 meV) was approximately twice that of the original detector. Results from a Cf source and pulsed neutrons will be presented.

Measurements of circular polarization from the 0.75-eV p-wave resonance of the La(n,)La reaction

遠藤 駿典; 藤岡 宏之*; 後藤 優*; 猪野 隆*; 岩本 修; 岩本 信之; 河村 しほり*; 木村 敦; 北口 雅暁*; 小林 龍珠; et al.

JPS Conference Proceedings (Internet), 45, p.011056_1 - 011056_8, 2026/06

https://doi.org/10.7566/JPSCP.45.011056

The NOPTREX collaboration aims to search for time-reversal symmetry breaking (T-violation) using compound nuclear reactions. To elucidate the mechanism of T-violation in compound nuclear reactions, we are measuring the spin-angle correlation term of the (n,) reaction. We have already successfully measured the angular distribution and transverse asymmetry of emitted gamma-rays for several nuclei, such as La and Sn. As the next step, we measured the circular polarization of the emitted gamma-rays from the 0.75-eV p-wave resonance of La(n,)La reactions. The measurements were performed at J-PARC MLF BL04 (ANNRI). The circular polarization of gamma-rays was measured using the developed gamma-ray polarimeter. Although the circular polarization observed was weak, this first measurement on the resonances allowed us to place limits on the circular polarization from the p-wave resonance. In this presentation, we will report the details of the experiment and future plans.

Incommensurate magnetic ordered phase with enhanced low-temperature magnetic specific heat in SmAuAl

東中 隆二*; Iwami, Takuma*; Saito, Kosuke*; 伊藤 孝; 田端 千紘; 金子 耕士; 大原 高志; 鬼柳 亮嗣; 中尾 朗子*; 中村 惇平*; et al.

Journal of the Physical Society of Japan, 95(6), p.063702_1 - 063702_5, 2026/06

https://doi.org/10.7566/JPSJ.95.063702

Neutron scattering and muon spin rotation (mSR) measurements on single-crystal SmAuAl reveal magnetically ordered states associated with successive transitions at 2.8 K and 0.9 K. Magnetic Bragg peaks appear below TN with an incommensurate propagation vector q = (0.30, 0, 1.33). mSR detects spontaneous internal fields below 2.8 K, and the spectral shape is consistent with the incommensurate magnetic ordering. No anomalies are observed at 0.9 K, indicating that the magnetic structure remains essentially unchanged.

Development of a circular-shape cathode element with pixel size of 0.8 0.8 mm for two-dimensional neutron detector

藤 健太郎; 中村 龍也; 坂佐井 馨; 山岸 秀志*

Journal of Physics; Conference Series, 3130(1), p.012012_1 - 012012_5, 2025/11

https://doi.org/10.1088/1742-6596/3130/1/012012

個別読み出し、マルチワイヤ型二次元中性子検出器において高精度な中性子測定を実現するため、画素サイズを小型化した検出器素子を開発した。開発した素子のピクセルサイズは0.80.8mmであり、素子はガス増幅用のマルチワイヤ陽極と中性子によって発生した電荷を収集し、入射中性子の位置を検出するための円形陰極バンプから構成されている。有感面積は102.4102.4mmであり、X, Y方向の間隔は0.8mmである。開発した検出素子に対する中性子均一照射試験をCf-252中性子源を用いて行った結果、2次元中性子検出器として優れた均一性を示し、全画素における中性子計数の広がりは9.9%であった。また試験により得られた位置分解能は半値幅で1.89mmであった。バックグラウンド計数率は8.2210cps/pixel、Co-60線源を用いたガンマ線感度の測定値は3.8710であった。

Development of a quantitative, radiation-resistant feeding pump for use in extraction chromatography techniques for MA(III) recovery

長谷川 健太; 安倍 弘; 高畠 容子; 渡部 創; 中村 雅弘; 佐野 雄一; 竹内 正行

Progress in Nuclear Science and Technology (Internet), 8, p.248 - 251, 2025/09

https://doi.org/10.15669/pnst.8.248

Japan Atomic Energy Agency has been working on development of extraction chromatography technology for recovery of trivalent minor actinides (MA(III): Am, Cm) from high-level radioactive liquid waste generated in reprocessing of spent nuclear fuel. In this project, a diaphragm pump with radiation resistant is being developed for use in feeding the liquid on the recovery system. In this study, the degradation behavior of ethylene-propylene-diene (EPDM) rubber, selected as a candidate diaphragm material for diaphragm pumps, was quantitatively evaluated by irradiation tests. The rubber samples were immersed in nitric acid solution under tensile load, and irradiated with gamma rays. After irradiation tests, tensile testing and dynamic mechanical analysis, and so on, were conducted to the rubber samples.

Study of the spin-memory effect with low-energy gamma-rays in Hf(n,)Hf reaction measurement

河村 しほり*; 遠藤 駿典; 岩本 修; 岩本 信之; 木村 敦; 北口 雅暁*; 中村 詔司; 奥平 琢也*; Rovira Leveroni, G.; 清水 裕彦*; et al.

EPJ Web of Conferences, 329, p.05002_1 - 05002_3, 2025/06

https://doi.org/10.1051/epjconf/202532905002

共鳴の全角運動量は低エネルギー核反応において重要なパラメータの一つである。実験から共鳴のJを推定する方法はいくつか提案されているが、本研究ではWetzelとThomasによって提案された、共鳴のガンマ線スペクトルにおいて、適切に選ばれた2つの低エネルギーガンマ線の強度比を比較する方法に着目した。この方法は、HuizengaとVandenboschによって提案されたスピンメモリー効果(SME)に基づいている。SMEとは、カスケード遷移において多くの中間励起準位が存在しても、初期の共鳴状態のスピン情報が残ることを意味する。強度比に現れるSMEの強さは、強度比の差から定量的に評価することができる。過去の測定結果から、原子番号Zがマジックナンバー(Z=50)付近でSMEが大きくなることが示唆されている。本研究ではZ=50から離れた元素である天然のHf(Z=72)を用いて、J-PARC・MLF・ANNRIにおいて中性子捕獲反応測定を行った。SMEの強さは、共鳴からの低エネルギー線の強度比から決定された。その結果、Hf(Z=72)で観測されたSMEはTa(Z=73)よりも非常に大きいことがわかった。

クリープ破断時間および高温引張強度予測モデルの連合学習

櫻井 惇也*; 鳥形 啓輔*; 松永 学*; 高梨 直人*; 日比野 真也*; 木津 健一*; 森田 聡*; 井元 雅弘*; 下畠 伸朗*; 豊田 晃大; et al.

鉄と鋼, 111(5), p.246 - 262, 2025/04

https://doi.org/10.2355/tetsutohagane.TETSU-2024-124

Creep testing is time-consuming and costly, leading institutions to limit the number of tests conducted to the minimum necessary for their specific objectives. By pooling data from each institution, it is anticipated that predictive models can be developed for a wide range of materials, including welded joints and degraded materials exposed to service conditions. However, the data obtained by each institution is often highly confidential, making it challenging to share with others. Federated learning, a type of privacy-preserving computation technology, allows for learning while keeping data confidential. Utilizing this approach, it is possible to develop creep life prediction models by leveraging data from various institutions. In this paper, we constructed global deep neural network models for predicting creep rupture life of heat-resistant ferritic steels in collaboration with eight institutions using the federated learning system we developed for this purpose. Each institution built a local model using only its own data for comparison. While these local models demonstrated good predictive accuracy for their respective datasets, their predictive performance declined when applied to data from other institutions. In contrast, the global model constructed using federated learning showed reasonably good predictive performance across all institutions. The distance between each institution's data was defined in the space of explanatory variables, with the NIMS data, which had the largest dataset, serving as the reference point. The global model maintained high predictive accuracy regardless of the distance from the NIMS data, whereas the predictive accuracy of the NIMS local model significantly decreased as the distance increased.

Spontaneous magnetic field and disorder effects in BaPtAsSb with a honeycomb network

足立 匡*; Ogawa, Taiki*; 小宮山 陽太*; 須村 拓也*; Saito-Tsuboi, Yuki*; Takeuchi, Takaaki*; Mano, Kohei*; Manabe, Kaoru*; 川端 幸樹*; 今津 毅士*; et al.

Physical Review B, 111(10), p.L100508_1 - L100508_6, 2025/03

https://doi.org/10.1103/PhysRevB.111.L100508

Chiral superconductivity exhibits the formation of novel electron pairs that breaks the time-reversal symmetry and has been actively studied in various quantum materials in recent years. However, despite its potential to provide definitive information, effects of disorder in the crystal structure on the chiral superconductivity has not yet been clarified, and therefore the investigation using a solid-solution system is desirable. We report muon-spin-relaxation (SR) results of layered pnictide BaPtAsSb with a honeycomb network composed of Pt and (As, Sb). We observed an increase of the zero-field SR rate in the superconducting (SC) state at the Sb end of , suggesting the occurrence of a spontaneous magnetic field due to the time-reversal symmetry breaking in the SC state. On the other hand, a spontaneous magnetic field was almost and completely suppressed for the As-Sb mixed samples of and 0.2, respectively, suggesting that the time-reversal symmetry-breaking SC state in is sensitive to disorder. The magnetic penetration depth estimated from transverse-field SR measurements at and 0.2 behaved like weak-coupling -wave superconductivity. These seemingly incompatible zero-field and transverse-field SR results of BaPtAsSb with could be understood in terms of chiral -wave superconductivity with point nodes on the three-dimensional Fermi surface.

Evaluation report for sludge measurement by nondestructive assay (Plutonium Scrap Multiplicity Counter)(Joint research)

谷川 聖史; 瀬谷 和仁*; 浅川 直也*; 林 宏幸*; 堀籠 和志; 向 泰宣; 北尾 貴彦; 中村 仁宣; Henzlova, D.*; Swinhoe, M. T.*; et al.

JAEA-Technology 2024-014, 63 Pages, 2025/02

JAEA-Technology-2024-014.pdf:3.02MB

プルトニウム転換技術開発施設の廃液処理工程で発生したスラッジ中のPu量を評価する上で、スラッジは生成上、多くの不純物(Na, Fe, Ni等)を含み不均質であるため、従来の破壊分析ではサンプリングによる代表性が乏しく、Pu量測定に係る測定不確かさが大きかった(約24%)。この測定不確かさを低減させるために、日本原子力研究開発機構と米国ロスアラモス国立研究所は共同で中性子を利用した非破壊測定装置のPlutonium Scrap Multiplicity Counter (PSMC)を用いた測定技術の開発を進めた。MOX粉末を用いた模擬スラッジやモンテカルロ法により検証等を行いPSMC検出器パラメーター(predelay, doubles gatefraction等)を最適化し、高分解能ガンマ線分光分析を組み合わせて測定した結果、含有不純物の影響はないことが確認でき、従来法と比べ新たに設定した非破壊測定方法における測定不確かさは約6.5%まで低減できた。さらに、PSMC測定値の妥当性を評価するため、IAEA立ち合いの下、ガンマ線を測定しPu量を評価するIn Situ Object Counting System (ISOCS)を用いた比較測定した結果、ISOCSとPSMCの測定値は両方の測定不確かさの範囲内で一致したため、PSMCによる測定値の妥当性が確認された。これらの結果より、本非破壊測定技術はスラッジのように不純物を多く含み、サンプリングの代表性が乏しいアイテムに有効であり、スラッジの計量管理に適用することが認められた。

Ag segregation and interfacial characterization of the hexagonal (MgSi)-phase in Al-Mg-Si-Ag alloy

Ahmed, A.*; Uttarasak, K.*; 土屋 大樹*; Lee, S.*; 西村 克彦*; 布村 紀男*; 池野 進*; Malik, A.*; 清水 一行*; 平山 恭介*; et al.

Materials Today Communications (Internet), 43, p.111835_1 - 111835_10, 2025/02

https://doi.org/10.1016/j.mtcomm.2025.111835

This study investigates the interface characteristics of the hexagonal (MgSi)-phase in Al-Mg-Si-Ag alloys, providing novel insights into its orientation relationship, interfacial conditions, misfit, and Ag segregation with the Al matrix. Using optical microscopy (OM), focused ion beam (FIB), and scanning transmission electron microscopy (STEM), we clarified the role of three distinct facets {111}//{111}, {122}//{110}, and {112}//{111} in determining the stability and properties of the hexagonal (MgSi)-phase. Unlike the conventional (MgSi)-phase with a {100} habit plane, the hexagonal -phase was found on the {111} habit plane, exhibiting a new orientation relationship [{111}//{111}, 110//110]. Ag segregation was notably observed at the interfaces of these facets, with varying concentrations influencing interfacial coherency and strain. These findings not only advance our understanding of microstructural evolution in Al-Mg-Si alloys but also provide a foundation for tailoring material properties through interface engineering. The results offer critical insights for optimizing alloy compositions and heat treatments to enhance mechanical properties and performance in practical applications.