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Er静間 俊行*; Omer, M.; 羽島 良一*; 小泉 光生; 高橋 時音; 角田 佑介*; 大塚 孝治*
Physical Review C, 113(4), p.044325_1 - 044325_9, 2026/04
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)Low-energy dipole excitations in Er were investigated via nuclear resonance fluorescence using a quasi-monoenergetic, linearly polarized photon beam produced at the High Intensity 
-ray Source (HIS) facility at Duke University. The parity of the excited states was determined from the azimuthal asymmetry in the intensities of resonantly scattered rays with respect to the polarization plane of the incident beam. Electric and magnetic dipole strengths were extracted for excitation energies between 2.2 and 3.5 MeV. The results are interpreted in terms of the nuclear scissors mode by comparing with large-scale shell-model calculations based on the Qasiparticle Vacua Shell Model. In addition, the characteristics of the E1 excitations are examined in comparison with those of neighboring rare-earth nuclei to explore their relations to collective octupole--vibrational two-phonon excitations. This work is a contribution of the Japan Atomic Energy Agency (JAEA) to the International Atomic Energy Agency (IAEA) under the agreement of the coordinated research program (CRP), J02015 (Facilitation of Safe and Secure Trade Using Nuclear Detection Technology - Detection of RN and Other Contraband). This work was a part of the study of NRF phenomenon aiming at nuclear security and safeguards applications, being supported by the subsidiary for "promotion of strengthening nuclear security or the like" of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.
-ray beam measurementsOmer, M.; 静間 俊行*; 小泉 光生; 平 義隆*; Zen, H.*; 大垣 英明*; 羽島 良一*
Radiation Physics and Chemistry, 240, p.113467_1 - 113467_8, 2026/03
被引用回数：1 パーセンタイル：50.28(Chemistry, Physical)Coaxial high-purity germanium detectors are widely used in applications requiring high-resolution -ray spectroscopy. However, the internal structure of these detectors, particularly the geometry of the inactive volumes inside the detector core, can significantly influence their performance in beam detection configurations. This study investigates the impact of detector structure on the spectral response to pencil-like -ray beams, based on a comparison of -ray spectra measured with two coaxial high-purity germanium detectors that have similar active volumes but distinct internal geometries. Experimental measurements were conducted at the UVSOR synchrotron facility using collimated laser Compton scattered -ray beams with an energy of 
MeV. Monte Carlo simulations using the Geant4 toolkit were performed to refine the detector models and replicate experimental results. The results reveal that the front layer thickness and the presence of structural elements such as the cold finger strongly affect the spectral features, particularly the appearance of a coincidence sum peak of the annihilation radiation at 1.022 MeV. Off-axis irradiation significantly improves the detection efficiency and reduces undesired induced interactions within inactive volumes. Additionally, the observed pair production signatures are validated through the available theoretical cross section data, confirming the dominant role of internal structures in shaping the detector response under beam geometry. These findings are essential for optimizing detector configurations in precision -ray beam experiments. This work is a contribution of the Japan Atomic Energy Agency (JAEA) to the International Atomic Energy Agency (IAEA) under the agreement of the coordinated research program (CRP), J02015 (Facilitation of Safe and Secure Trade Using Nuclear Detection Technology - Detection of RN and Other Contraband). A part of this work was conducted at the BL1U of UVSOR Synchrotron Facility, Institute for Molecular Science (IMS program 23IMS6602).
池谷 正太郎; 鈴木 武; 横堀 智彦; 菅原 聡; 横田 顕; 菊地 絃太; 村口 佳典; 北原 理; 瀬谷 真南人; 黒澤 剛史; et al.
JAEA-Technology 2025-001, 169 Pages, 2025/08
JAEA-Technology-2025-001.pdf:14.22MB
原子力科学研究所の放射性廃棄物処理場は、多様な施設により構成されており、その中に、第3廃棄物処理棟、解体分別保管棟及び減容処理棟がある。これらの3建家は、核原料物質、核燃料物質及び原子炉の規制に関する法律による規制を受けており、耐震重要度分類でCクラスに分類されている。東京電力福島第一原子力発電所の事故を契機として原子力規制委員会が策定した新規制基準に対応するため、最新の建築基準法に基づき3建家の耐震評価を実施したところ、許容応力度評価で一部基準を満足しない箇所が認められた。これに対応すべく、令和3年3月5日に設計及び工事の計画の認可(設工認)を取得し、令和3年(2021)から令和4年(2022)までの期間にて耐震補強を行った。本報告書は、第3廃棄物処理棟、解体分別保管棟及び減容処理棟の各建家の耐震設計の概況をはじめ、耐震改修工事の工事概要、作業体制、安全管理、使用前事業者検査について取りまとめたものである。
He neutron spin filter at J-PARC高橋 慎吾; 鬼柳 亮嗣; 奥平 琢也*; 高田 秀佐*; 小林 龍珠; 奥泉 舞桜; 猪野 隆*; 浅井 寛太*; 土川 雄介; 及川 健一; et al.
Nuclear Instruments and Methods in Physics Research A, 1075, p.170410_1 - 170410_8, 2025/06
被引用回数：2 パーセンタイル：51.17(Instruments & Instrumentation)This study developed a compact and portable in-situ He neutron spin filter ( He NSF) utilizing spin-exchange optical pumping at MLF of J-PARC. Its performance as an incident neutron polarizer was evaluated at MLF, where it achieved a He polarization exceeding 0.6, corresponding to a neutron polarization greater than 0.8 at 1.8 
. Notably, the He NSF demonstrated stable operation for 110 h. These outcomes signify that the developed in-situ He NSF facilitates and promotes polarized pulsed neutron experiments at MLF.
Np, 
Am, and 
Am reaction rates in highly enriched uranium fuel cores at Kyoto University Critical AssemblyPyeon, C. H.*; 大泉 昭人; 方野 量太; 福島 昌宏
Nuclear Science and Engineering, 199(3), p.429 - 444, 2025/03
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)京都大学KUCAの高濃縮ウラン燃料による複数の炉心で取得したNp、Am、Amの核分裂率とNp捕獲反応率に関する積分実験データに対して、ENDF/B-VIII.0及びJENDL-5とSerpent2コードを用いた実験解析を実施した。Np/
U、Am/U、Am/Uの核分裂率比の実験値と解析値の比較では、ENDF/B-VIII.0及びJENDL-5のいずれにおいて、それぞれ約5、15、および10%の精度が示された。Np/
Auの捕獲反応率比については、熱中性子スペクトルの炉心において高い精度が得られることを明らかにした。また、Np/U、Am/U、Am/Uの核データに起因した不確かさは、概ね4%以内であることを示した。
遠藤 駿典; 安部 亮太*; 藤岡 宏之*; 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.
European Physical Journal A, 60(8), p.166_1 - 166_10, 2024/08
被引用回数：5 パーセンタイル：73.54(Physics, Nuclear)Measurements of -ray circular polarization emitted from neutron capture reactions provide valuable information for nuclear physics studies. The spin and parity of excited states can be determined by measuring the circular polarization from polarized neutron capture reactions. Furthermore, the -ray circular polarization in a neutron capture resonance is crucial for studying the enhancement effect of parity nonconservation in compound nuclei. The -ray circular polarization can be measured using a polarimeter based on magnetic Compton scattering. A polarimeter was constructed, and its performance indicators were evaluated using a circularly polarized -ray beam. Furthermore, as a demonstration, the -ray circular polarization was measured in 
S(n,)
S reactions with polarized neutrons.
Lan, Z.*; 有川 安信*; Mirfayzi, S. R.*; Morace, A.*; 早川 岳人*; 佐藤 博隆*; 加美山 隆*; Wei, T.*; 巽 湧太*; 小泉 光生; et al.
Nature Communications (Internet), 15, p.5365_1 - 5365_7, 2024/07
被引用回数：13 パーセンタイル：86.29(Multidisciplinary Sciences)The temperature measurement of material inside of an object is one of the key technologies for control of dynamical processes. For this purpose, various techniques such as laser-based thermography and phase-contrast imaging thermography have been studied. However, it is, in principle, impossible to measure the temperature of an element inside of an object using these techniques. One of the possible solutions is measurements of Doppler brooding effect in neutron resonance absorption (NRA). Here we present a method to measure the temperature of an element or an isotope inside of an object using NRA with a single neutron pulse of approximately 100 ns width provided from a high-power laser. We demonstrate temperature measurements of a tantalum (Ta) metallic foil heated from the room temperature up to 617 K. Although the neutron energy resolution is fluctuated from shot to shot, we obtain the temperature dependence of resonance Doppler broadening using a reference of a silver (Ag) foil kept to the room temperature. A free gas model well reproduces the results. This method enables element(isotope)-sensitive thermometry to detect the instantaneous temperature rise in dynamical processes.
方野 量太; 大泉 昭人; 福島 昌宏; Pyeon, C. H.*; 山本 章夫*; 遠藤 知弘*
Nuclear Science and Engineering, 198(6), p.1215 - 1234, 2024/06
被引用回数：1 パーセンタイル：12.78(Nuclear Science & Technology)京都大学臨界集合体A架台で測定された鉛ビスマスサンプル反応度を用いたデータ同化によって加速器駆動システムの冷却材ボイド反応度の鉛ビスマス非弾性散乱断面積に起因した不確かさを低減できることを実証した。サンプル反応度について、データ同化の式中に現れる実験不確かさと相関を再評価し、結果を明示した。不確かさ評価に用いる感度係数はMCNP6.2で評価し、データ同化はMARBLEを用いて実行した。鉛ビスマスに対してサンプル反応度は感度係数が大きいため、加速器駆動システムの冷却材ボイド反応度の断面積起因不確かさを6.3%から4.8%まで減少させ、本研究で設定した暫定的な目標精度5%を達成できることを示した。さらに、ADJ2017に使用された積分実験データを用いることで、マイナーアクチニドや鉄など他の支配的な核種に起因する不確かさを効果的に低減できることを示した。
Omer, M.; 静間 俊行*; 羽島 良一*; 小泉 光生
Journal of Applied Physics, 135(18), p.184903_1 - 184903_10, 2024/05
被引用回数：4 パーセンタイル：43.27(Physics, Applied)We report on the findings of a quantitative nondestructive analysis of the natural isotopic abundances of hafnium and tungsten elements using nuclear resonance fluorescence. Commercial samples of hafnium and tungsten were irradiated to six quasi-monochromatic -ray beams generated by laser Compton scattering in the energy range of 2.4-3.2 MeV. Multiple nuclei were simultaneously excited at each of the six -ray beam energies. A high-purity germanium detector array detected deexcitations of the nuclei. In total, 
transitions were unprecedentedly employed to estimate the isotopic abundances of heavy elements nondestructively. The estimated abundances of three hafnium isotopes and three tungsten isotopes are consistent with standard known natural abundances within the experimental uncertainties. The deviation from the standard values ranges from 0.18% to 1.36%. This work is a contribution of the Japan Atomic Energy Agency (JAEA) to the International Atomic Energy Agency (IAEA) under the agreement of the coordinated research program (CRP), J02015 (Facilitation of Safe and Secure Trade Using Nuclear Detection Technology - Detection of RN and Other Contraband). This work was a part of a study of the nuclear resonance fluorescence aiming at nuclear security and safeguards applications, being supported by the subsidiary for "promotion of strengthening nuclear security or the like" of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.
Ta静間 俊行*; Omer, M.; 羽島 良一*; 小泉 光生
Physical Review C, 109(5), p.054320_1 - 054320_8, 2024/05
被引用回数：2 パーセンタイル：42.78(Physics, Nuclear)Low-lying levels in the odd-mass nucleus Ta have been populated via nuclear resonance fluorescence using a quasi-monoenergetic, linearly polarized photon beam at the High Intensity -ray Source (HIS) facility at Duke University. The spin and parity of the levels were determined from the azimuthal intensity asymmetry of resonantly scattered -rays with respect to the polarization plane of the incident photon beam. The electric and magnetic dipole strengths were obtained for excitation energies from 2.2 to 3.2 MeV. The results are discussed in terms of the nuclear scissors mode. This work is a contribution of the Japan Atomic Energy Agency (JAEA) to the International Atomic Energy Agency (IAEA) under the agreement of the coordinated research program (CRP), J02015 (Facilitation of Safe and Secure Trade Using Nuclear Detection Technology - Detection of RN and Other Contraband). This work was a part of a study of the nuclear resonance fluorescence aiming at nuclear security and safeguards applications, being supported by the subsidiary for "promotion of strengthening nuclear security or the like" of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.
-ray elastic scatteringOmer, M.; 静間 俊行*; 小泉 光生; 羽島 良一*; 橋本 智*; 宮本 修治*
LASTI Annual Report, 24, p.20 - 22, 2023/12
Nondestructive elemental analysis is highly valued in many fields such as archeology, paleontology, space sciences, nuclear security, and nuclear nonproliferation. These fields usually impose estimating the elemental composition of bulk, large, and inhomogeneous samples nondestructively. Common elemental analysis techniques such as X-ray fluorescence (XRF) may fail in such situations due to self-absorption of low energy X-rays within thin layers of the sample. In the present study, we propose a novel nondestructive method that may be useful in distinguishing the elemental composition of a given sample based on the elastic scattering of linearly polarized and high-energy -rays. Linear polarization of -rays causes asymmetry of the elastic scattering cross sections with respect to the polarization plane of the incident -rays. At specific -ray energies and scattering angles, the asymmetry ratio, R, of the cross sections in two orthogonal planes is characteristic of each element. The measurement of asymmetry ratio of 1.62 MeV linearly polarized -rays at NewSUBARU facility is presented. This work is a contribution of the JAEA to the International Atomic Energy Agency (IAEA) under the agreement of the coordinated research program (CRP), J02015 (Facilitation of Safe and Secure Trade Using Nuclear Detection Technology - Detection of RN and Other Contraband).
Pyeon, C. H.*; 方野 量太; 大泉 昭人; 福島 昌宏
Nuclear Science and Engineering, 197(11), p.2902 - 2919, 2023/11
被引用回数：3 パーセンタイル：40.29(Nuclear Science & Technology)京都大学臨界集合体(KUCA)の固体減速・反射炉心においてアルミ、鉛、ビスマスサンプルとボイドを模擬するアルミスペーサを用いてサンプルおよびボイド反応度実験が行われた。実験値と比較して、JENDL-4.0とMCNP6.2を用いた固有値計算によるサンプル反応度は良い精度で得られた。また、ボイド反応度についてはJENDL-4.0の結果とENDF/B-VII.1の計算結果はともに実験値と比べて良い一致を示した。MCNP6.2/ksenによって得られた感度係数とENDF/B-VII.1に基づくSCALE6.2の共分散データを用いてサンプルおよびボイド反応度の不確かさを定量化し、アルミ、鉛、ビスマスの断面積に起因する不確かさの影響を明らかにした。ボイドを模擬するアルミスペーサを用いた一連の反応度実験解析により、KUCAの固体減速・反射炉心中のボイドを解析する手法を実証した。
Omer, M.; 静間 俊行*; 小泉 光生; 平 義隆*; Zen, H.*; 大垣 英明*; 羽島 良一
UVSOR-50, P. 37, 2023/08
核共鳴蛍光(NRF)を用いた非破壊分析において、試料温度によるドップラー効果による影響を調べることを目的とした研究を開始した。今回は、波長1980nmのファイバーレーザーを加速エネルギー746MeVの電子ビームと衝突させて生成した最大エネルギー5.54MeVのレーザーコンプトンガンマ線を
Pb標的に照射し、共鳴散乱ガンマ線を3台の高純度ゲルマニウム検出器を用いて測定した。その結果、レーザーコンプトンガンマ線最大エネルギーよりも高いエネルギーで、複数のガンマ線ピークが観測された。これらのガンマ線は、実験室内の制動放射線によって発生した中性子が測定装置の周囲の物質と反応した後に放出された中性子捕獲即発ガンマ線であると考えられる。そのため、バックグラウンドガンマ線の低減のため、ゲルマニウム検出器の周囲を厚さ10cmの鉛を用いて遮蔽した。その結果、即発ガンマ線のバックグラウンドは抑制され、Pbの共鳴散乱ガンマ線を観測することができた。
岡村 知拓*; 方野 量太; 大泉 昭人; 西原 健司; 中瀬 正彦*; 朝野 英一*; 竹下 健二*
Journal of Nuclear Science and Technology, 60(6), p.632 - 641, 2023/06
被引用回数：4 パーセンタイル：40.06(Nuclear Science & Technology)動的な核燃料サイクルシミュレーションの燃焼計算への適用を目的に、行列指数法を修正してOkamura explicit method (OEM)を開発した。OEMは、長いタイムステップであっても、短半減期核種の計算の発散を抑制することが可能である。OEMの計算コストはオイラー法と同等で小さく、燃料サイクルシミュレーションに十分な精度を保つことができる。
余語 覚文*; Lan, Z.*; 有川 安信*; 安部 勇輝*; Mirfayzi, S. R.*; Wei, T.*; 森 隆人*; Golovin, D.*; 早川 岳人*; 岩田 夏弥*; et al.
Physical Review X, 13(1), p.011011_1 - 011011_12, 2023/01
被引用回数：47 パーセンタイル：96.80(Physics, Multidisciplinary)Neutrons are powerful tools for investigating the structure and properties of materials used in science and technology. Recently, laser-driven neutron sources (LDNS) have attracted the attention of different communities, from science to industry, in a variety of applications, including radiography, spectroscopy, security, and medicine. However, the laser-driven ion acceleration mechanism for neutron generation and for establishing the scaling law on the neutron yield is essential to improve the feasibility of LDNS. In this paper, we report the mechanism that accelerates ions with spectra suitable for neutron generation. We show that the neutron yield increases with the fourth power of the laser intensity, resulting in the neutron generation of 
in 
at a maximum, with 
Wcm
, 900 J, 1.5 ps lasers. By installing a "hand-size" moderator, which is specially designed for the LDNS, it is demonstrated that the efficient generation of epithermal (0.1-100 eV) neutrons enables the single-shot analysis of composite materials by neutron resonance transmission analysis (NRTA). We achieve the energy resolution of 2.3% for 5.19-eV neutrons 1.8 m downstream of the LDNS. This leads to the analysis of elements and isotopes within sub-
s times and allows for high-speed nondestructive inspection.
Omer, M.; 静間 俊行*; 羽島 良一*; 小泉 光生
第43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), 3 Pages, 2022/11
Gamma-rays originated from laser Compton scattering (LCS) are convenient photon sources for nondestructive interrogation of nuclear materials. LCS can be used with nuclear resonance fluorescence (NRF) and X-ray fluorescence (XRF), the two of which are considered photon-based active interrogation techniques. However, an accurate estimation of the incident LCS -ray flux is crucial. The -ray flux is customarily measured using high purity germanium (HPGe) detectors, usually calibrated using standard point-like radioactive -ray sources. These standard sources are entirely different from LCS beams in terms of detection geometry. Therefore, the calibration process must be corrected to meet the LCS beam conditions. Here, we demonstrate how to implement the required corrections and provide experimental validation of these corrections.
中村 龍也; 藤 健太郎; 小泉 智克; 鬼柳 亮嗣; 大原 高志; 海老根 守澄; 坂佐井 馨
Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 2 Pages, 2022/11
J-PARC物質・生命科学実験施設に設置されたSENJU回折計用として、新たに薄型の位置敏感シンチレータ中性子検出器を開発した。本検出器は既設のオリジナル検出器と同等の有感面積(256
256mm)とピクセル分解能(44mm)を保持しつつ、奥行きは12cm(オリジナルの40%)の薄型へと改良した。製作した6台の検出器はいずれも検出効率60%(2A)、計数均一性5-8%と良好な性能を示した。現在、これらの検出器はビームライン内の回折計に装填されており、数か月の安定動作が確認されている。
Omer, M.; 静間 俊行*; 羽島 良一*; 小泉 光生
Radiation Physics and Chemistry, 198, p.110241_1 - 110241_7, 2022/09
被引用回数：8 パーセンタイル：66.04(Chemistry, Physical)In beam geometries where a directed -ray beam hits the surface of a coaxial high purity germanium detector (HPGe), the detector efficiency is sensitive to the position where -rays initially hit the detector surface because the structure of the detector is nonuniform. This may cause inaccuracy of the detector efficiency when measured using standard sources that are point-like sources emitting -rays isotropically. Obtaining a precise estimation of the full energy peak efficiency of the coaxial HPGe detector in the beam geometry for on-axis and off-axis measurements requires a Monte Carlo simulation. We performed a Monte Carlo simulation that calculates the detector efficiency in the beam geometry. The effects of the off-axis distance and -ray beam size on the efficiency are quantitatively analyzed. We found that the intrinsic efficiency in the beam geometry is maximized when the beam hits the detector at specific off-axis distances. Our Monte Carlo calculations have been supported by a nuclear resonance fluorescence experiment using laser Compton scattering -ray beam.
岡村 知拓*; 西原 健司; 方野 量太; 大泉 昭人; 中瀬 正彦*; 朝野 英一*; 竹下 健二*
JAEA-Data/Code 2021-016, 43 Pages, 2022/03
JAEA-Data-Code-2021-016.pdf:3.06MB
今後の核燃料サイクルの確立・高度化には、将来の原子力発電シナリオに応じて発生する多様なマスバランスを定量的に予測・分析することが求められる。しかし、核燃料サイクルはフロントエンドからバックエンドまでの多様な工程によって構成されており、モデル化の複雑さ、想定されるシナリオの多様さなどからシナリオの分析は容易ではない。そこで日本原子力研究開発機構と東京工業大学は、天然ウランの採掘から地層処分の核種移行工程までのマスバランスを統合的に解析するためのツールとしてNMBコードを開発した。NMBコードは、汎用性のある各工程の記述、広範なデータベース、高速な核種変換計算などを備え、ユーザーが指定する発電量や再処理容量などの条件に基づいて、各工程におけるマスバランスを定量化することができる。またNMBコードは多様なステークホルダーが利用できるように実行プラットフォームをMicrosoft Excel(R)としている。本ユーザーマニュアルでは、NMB4.0版のデータベースならびにシナリオ入力を作成する方法を述べる。
岡村 知拓*; 方野 量太; 大泉 昭人; 西原 健司; 中瀬 正彦*; 朝野 英一*; 竹下 健二*
Bulletin of the Laboratory for Advanced Nuclear Energy, 6, p.29 - 30, 2022/02
東京工業大学竹下研究室では日本原子力研究開発機構(JAEA)と共同で、Nuclear Material Balance code version 4.0 (NMB4.0)の開発を実施してきた。本レポートはNMB4.0の概要と機能をまとめたものである。
