Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
)
(SrAl
TaO)
with 
伊藤 孝; 髭本 亘; 幸田 章宏*; 中村 惇平*; 下村 浩一郎*
Interactions (Internet), 245(1), p.25_1 - 25_7, 2024/12
We report on muon spin relaxation (
SR) measurements in a mixed perovskite compound, (LaAlO)
(SrAlTaO) with (LSAT), which is widely used as a single-crystalline substrate for thin film deposition. In zero applied field (ZF), muon depolarization due to the distribution of nuclear dipole fields was observed in the temperature range from 4 K to 270 K. Interestingly, SR time spectra in ZF maintained a Gaussian-like feature over the entire range, while the depolarization rate exhibited a monotonic decrease with increasing temperature. This behavior may be attributed to the thermally activated diffusion of muons between a few adjacent sites within a confined space of the angstrom scale, where the motionally averaged local field that each muon experiences can remain non-zero and result in maintaining the Gaussian-like line shape. The spatial distribution of electrostatic potential at lattice interstices evaluated via density functional theory calculations suggests that such a restriction of muon diffusion paths can be caused by the random distribution of cations with different nominal valences in the mixed perovskite lattice.
下村 浩一郎*; 幸田 章宏*; Pant, A. D.*; 砂川 光*; 藤森 寛*; 梅垣 いづみ*; 中村 惇平*; 藤原 理賀; 反保 元伸*; 河村 成肇*; et al.
Interactions (Internet), 245(1), p.31_1 - 31_6, 2024/12
J-PARC Muon Facility: MUSE (Muon Science Establishment) is responsible for the inter-university user program and the operation, maintenance, and construction of the muon beamlines, namely D-line, S-line, U-line, and H-line, along with the muon source at J-PARC Materials and Life Science Facility (MLF). In this paper, recent developments are briefly presented.
伊藤 真司*; 清水 浩之*; 大野 進太郎*; 高山 裕介
土木学会論文集(インターネット), 80(8), p.24-00030_1 - 24-00030_18, 2024/08
放射性廃棄物の地層処分施設の設計検討では、建設・操業段階から閉鎖後長期にわたって生じ得る現象を考慮した力学挙動評価が求められる。このような背景のもと、長期力学解析コードMACBECEの開発を進めている。本研究では、廃棄体の発熱や地下水による再冠水などの過渡的な現象を考慮できるように、不飽和土の弾塑性構成モデルや、熱伝導/浸透流解析との連携機能を導入することで、過渡期から長期まで一貫して評価できる解析コードを構築した。そして、幌延深地層研究センターにおける原位置試験の再現解析を実施し、計測データとの比較・分析により妥当性を確認した。その結果、二次元解析の制約による乖離が一部みられるものの、機能拡張した解析コードは計測データを良好に再現できることがわかった。
二宮 和彦*; 久保 謙哉*; 稲垣 誠*; 吉田 剛*; 竹下 聡史*; 反保 元伸*; 下村 浩一郎*; 河村 成肇*; Strasser, P.*; 三宅 康博*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 333(7), p.3445 - 3450, 2024/07
A novel nondestructive light element analysis method for bulk materials using muon beams was demonstrated. This method is based on the lifetime measurement of muons in a material and performed by measuring muon-decay electrons and identifying elements using the atomic number based on muon lifetimes. Muon irradiation on pure iron and two steel samples with known carbon contents was conducted to prepare a calibration curve for the quantitative analysis. We also performed a muon lifetime measurement for a Japanese sword and successfully determined its carbon content as 0.51 wt% using the calibration curve, without sample destruction.
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
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.
服部 高典; 鈴木 浩二*; 三代 達也*; 伊藤 崇芳*; 町田 真一*
Nuclear Instruments and Methods in Physics Research A, 1059, p.168956_1 - 168956_9, 2024/02
被引用回数：0 パーセンタイル：0.02(Instruments & Instrumentation)見込み幅0.5mmのラジアルコリメータを高圧中性子回折実験用に特別に設計し、その性能と有効性を調べた。0.75mm, 1.5mm, 3.0mmのラジアルコリメータはそれぞれ0.50mm, 1.07mm, 2.78mmのみこみ幅を示した。3つのラジアルコリメータの透過率はすべて同等であった。Paris-Edinburgh(PE)プレスとdiamond anvil cell (DAC)を使用した評価では、見込み幅0.5mmラジアルコリメータを使用した場合、アンビル散乱はかなり減少し、サンプル/アンビル信号比はPEプレスとDACでそれぞれ0.5と2.0に達した。これらの結果は、見込み幅0.5mmラジアルコリメータが意図したとおりに製作され、高圧中性子回折実験(特に30GPaを超える実験)に有効であることを示している。今回作成されたラジアルコリメータの見込み幅は、これまで世界の中性子散乱実験用に製作されたものの中で、最も小さい見込み幅を持つものである。
池田 一貴*; 佐次田 頌*; 大友 季哉*; 大下 英敏*; 本田 孝志*; 羽合 孝文*; 齋藤 開*; 伊藤 晋一*; 横尾 哲也*; 榊 浩司*; et al.
International Journal of Hydrogen Energy, 51(Part A), p.79 - 87, 2024/01
被引用回数：0 パーセンタイル：0.01(Chemistry, Physical)Low-vanadium-concentration alloys have low durability, and their hydrogen absorption and desorption amounts decrease by 20% after 100 cycles. In this study, we conducted reverse Monte Carlo modeling on X-ray diffraction patterns and neutron pair distribution functions of the hydrogen-absorbed and desorbed samples of a V
Ti
Cr
alloy to analyze the variations in the local structure. The local structure surrounding the hydrogen atom in the hydrogen-absorbed phase exhibited minimal changes. In contrast, hydrogen occupied both tetrahedral and octahedral sites of the hydrogen-desorbed phase almost equally during the early cycles; however, the amount of hydrogen occupying the tetrahedral sites increased with the number of cycles.
Lee, J.; 弘中 浩太; 伊藤 史哲*; 小泉 光生; 堀 順一*; 佐野 忠史*
Journal of Nuclear Science and Technology, 61(1), p.23 - 30, 2024/01
被引用回数：0 パーセンタイル：0.01(Nuclear Science & Technology)In the short-distance time-of-flight (TOF) measurements, the background events increase exponentially with decreasing the distance, and the high background increases the uncertainty of the measurement data. The moderated neutron beam includes the time-dependent background originating from the neutron moderator, such as 2.2 MeV gamma rays emitted by 
H(n,
) reaction in the moderator. In this paper, to achieve a compact neutron resonance transmission analysis system with high accuracy, we studied the relationship between the moderator and time-dependent background due to gamma rays. Monte Carlo simulations were carried out with the PHITS and the JENDL-4.0 to investigate the time distributions of neutrons and gamma rays emitted from the moderator. Ratios of the gamma-ray intensity to neutron intensity (S/S
ratio) were calculated for various moderators and flight distances. From the obtained results, moderator designs for maintaining low S/S ratio were discussed.
二宮 和彦*; 久保 謙哉*; 稲垣 誠*; 吉田 剛*; Chiu, I.-H.; 工藤 拓人*; 浅利 駿介*; 千徳 佐和子*; 竹下 聡史*; 下村 浩一郎*; et al.
Scientific Reports (Internet), 14, p.1797_1 - 1797_8, 2024/01
被引用回数：0 パーセンタイル：0.05(Multidisciplinary Sciences)鋼の特性を決める上で重要な鋼中のC量は、鋼の生産技術に大きく左右される。このため、ミュオンを使って鋼のC含有量を非破壊で測定する新しい方法を提案する。この方法は、生産中の鋼の品質管理だけでなく、貴重な鋼製考古学的遺物の分析にも使えるかもしれない。負の電荷を持つミュオンは原子系を形成し、最終的には核に吸収されるか電子に崩壊する。ミュオンの寿命は、Fe原子かC原子に捕らわれるかによってかなり違い、ミュオン停止位置での元素含有量をミュオン寿命測定で特定できる。C/Feのミュオン捕獲確率とCの元素含有量の関係は直線的で、ミュオン寿命測定で鋼のC含有量を定量的に決められる。さらに、ミュオンの入射エネルギーを調整して、0.5mm厚の3種類の鋼板からなる積層サンプルの各層でミュオンを停止させ、0.20-1.03wt%の範囲でC含有量を深さ選択的に、サンプルを壊さずに決定することに成功した。
伊藤 孝; 髭本 亘; 下村 浩一郎*
Physical Review B, 108(22), p.224301_1 - 224301_11, 2023/12
被引用回数：1 パーセンタイル：44.21(Materials Science, Multidisciplinary)In positive muon spin rotation and relaxation (SR) spectroscopy, positive muons () implanted into solid oxides are conventionally treated as immobile spin-probes at interstitial sites below room temperature. This is because each is thought to be tightly bound to an oxygen atom in the host lattice to form a muonic analogue of the hydroxy group. On the basis of this concept, anomalies in SR spectra observed in oxides have been attributed in most cases to the intrinsic properties of host materials. On the other hand, global diffusion with an activation energy of 
0.1~eV has been reported in some chemically-substituted perovskite oxides at cryogenic temperatures, although the reason for the small activation energy despite the formation of the strong O
bond has not yet been quantitatively understood. In this study, we investigated interstitial diffusion in the perovskite oxide lattice using KTaO cubic perovskite as a model system. We used the SR method and density functional theory calculations along with the harmonic transition state theory to study this phenomenon both experimentally and theoretically. Experimental activation energies for global diffusion obtained below room temperature were less than a quarter of the calculated classical potential barrier height for a bottleneck transfer path. The reduction in the effective barrier height could be explained by the harmonic transition state theory with a zero-point energy correction; a significant difference in zero-point energies for at the positions in the O bonding equilibrium state and a bond-breaking transition state was the primary cause of the reduction. This suggests that the assumption of immobile in solid oxides is not always satisfied since such a significant decrease in diffusion barrier height can also occur in other oxides.
美崎 慧*; 三輪 寛子*; 伊藤 孝; 吉田 健文*; 長谷川 慎吾*; 中村 由紀奈*; 徳竹 駿太*; 高畠 萌*; 下村 浩一郎*; Chun, W.-J.*; et al.
ACS Catalysis, 13(18), p.12281 - 12287, 2023/09
被引用回数：2 パーセンタイル：55.84(Chemistry, Physical)The direct alkylation of benzenes with simple alkanes is one of the ideal processes for the production of alkylbenzenes. We demonstrated that Pd nanoparticles on the outer surface of H-ZSM-5 are efficient catalysts for direct alkylation. The reaction proceeds through the activation of an alkane on the acid sites present inside the zeolite pores. This process is followed by the nucleophilic addition of an arene to the activated alkane. The spillover of the abstracted hydrogen atoms from the acid sites to the Pd nanoparticles on the outer surface accelerates recombination to H
. A maximum toluene conversion of 58.5% and selectivity of 95.6% for the alkylated products are achieved when toluene is reacted with 
-heptane. 
-selective alkylation is achieved, due to the effect of the pore size of H-ZSM-5. The SR study of muonium, a pseudo-isotope of hydrogen, in aluminosilicates suggested that the formation of atomic hydrogen is possible and its lifetime is in the sub-microsecond range or longer, which is long enough for chemical reactions.
弘中 浩太; Lee, J.; 小泉 光生; 伊藤 史哲*; 堀 順一*; 寺田 和司*; 佐野 忠史*
Nuclear Instruments and Methods in Physics Research A, 1054, p.168467_1 - 168467_5, 2023/09
被引用回数：0 パーセンタイル：0.02(Instruments & Instrumentation)We propose neutron resonance fission neutron analysis (NRFNA), an active nondestructive assay (NDA) technique, to improve the capability to identify and quantify a small amount of fissile material in a sample. NRFNA uses pulsed neutrons to induce fission reactions in the sample. Fission neutrons are detected by a neutron-gamma pulse shape discrimination (PSD) scintillation detector with time-of-flight (TOF) technique. The obtained nuclide-specific resonance peaks in the neutron energy spectrum provide information to identify and quantify a fissile material in the sample. The possibility of using PSD for NRFNA was confirmed through a test experiment using a natural uranium sample. We successfully observed the resonance peaks from 
U(n,f) reaction and showed that NRFNA would be useful for measuring a small amount of fissile material in a sample.
SR) methods伊藤 孝; 下村 浩一郎*
Hydrogenomics; The Science of Fully Utilizing Hydrogen (Internet), p.43 - 49, 2023/03
A brief introduction to the muon spin rotation, relaxation, and resonance (SR) methods is given for researchers and students involved in hydrogen science research. The text includes several examples of how the SR methods can be used to elucidate the behavior of hydrogen in materials.
下村 浩一郎*; 幸田 章宏*; Pant, A. D.*; 名取 寛顕*; 藤森 寛*; 梅垣 いづみ*; 中村 惇平*; 反保 元伸*; 河村 成肇*; 手島 菜月*; et al.
Journal of Physics; Conference Series, 2462, p.012033_1 - 012033_5, 2023/03
被引用回数：0 パーセンタイル：0.21(Physics, Applied)At J-PARC MUSE, since the SR2017 conference and up to FY2022, there have been several new developments at the facility, including the completion of a new experimental area S2 at the surface muon beamline S-line and the first muon beam extraction to the H1 area in the H-line, mainly to carry out high-statistics fundamental physics experiments. Several new studies are also underway, such as applying negative muon non-destructive elemental analysis to the analysis of samples returned from the asteroid Ryugu in the D2 area of the D-line. This paper reports on the latest status of MUSE.
町田 昌彦; Shi, W.*; 山田 進; 宮村 浩子; 吉田 亨*; 長谷川 幸弘*; 岡本 孝司; 青木 勇斗; 伊藤 倫太郎; 山口 隆司; et al.
Proceedings of Waste Management Symposia 2023 (WM2023) (Internet), 11 Pages, 2023/02
In order to find radioactive hot spots inside reactor building rooms from structural data together with air dose rate measurement data, Least Absolute Shrinkage and Selection Operator (LASSO) has been recently suggested as a promising scheme. The scheme has been examined in simplified room models and its high estimation feasibility has been confirmed by employing Particle and Heavy Ion Transport code System (PHITS) as a radiation simulation code. In this paper, we apply the scheme to complex room models inside real reactor buildings. The target rooms are pool canal circulation system room and main circulation system room in Japan Materials Testing Reactor (JMTR) at Oarai area, Japan Atomic Energy Agency (JAEA). In these real rooms, we create STL format structural data based on Computer Aided Design (CAD) models made directly from their point group data measured by laser scanning devices, and we notice that the total number of their surface meshes in these real rooms reaches to the order of 1 million. Then, this order of the mesh number clearly indicates that one needs a simplified radiation simulation code considering only direct transmission of gamma ray as a radiation calculation instead of PHITS demanding high computational costs. By developing such a simplified code and customizing it to perform LASSO scheme, we consequently confirm that LASSO scheme driven by the simplified simulation can also successfully predict unknown radioactive hot spots on real structural models.
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：6 パーセンタイル：93.39(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.
藤山 浩樹*; 高橋 博樹; 岡部 晃大; 伊藤 雄一*; 畠山 衆一郎; 鈴木 隆洋*; 大津 聡*; 山川 龍人*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (インターネット), p.529 - 531, 2023/01
J-PARC加速器のコリメータやワイヤースキャナモニタの機械駆動には、ステッピングモータが使用されている。これらの駆動装置ハードウェアは、J-PARC建設当初から使用されているものが多く経年劣化対策が必要となっている。そこで、2017年ごろからモーターや制御系の更新を進めることとなった。ところが、RCS H0コリメータのステッピングモータを現行品に更新したところ、誤動作が生じた。これは、モータードライバから発生するノイズにより、駆動部制御系がLS(リミットスイッチ)の状態を正しく認識できず、動作に支障が生じたものであった。確認のため、新旧のステッピングモータから発生するノイズを簡易テスト環境で測定したところ、明らかに現行品の方が大きいことが明らかとなった。そこで対策として、1本の多芯ケーブルに束ねられたステッピングモータの配線を、電源系とLS信号系に分離したところ、ノイズレベルが1/10程度になり、正常な動作を取り戻すことができた。本件では、RCS H0コリメータ駆動部のノイズ対策について報告する。
伊藤 史哲*; Lee, J.; 弘中 浩太; 小泉 光生; 余語 覚文*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (インターネット), p.137 - 140, 2023/01
中性子共鳴透過分析(NRTA)は、パルス中性子を計量したい核物質に照射し、飛行時間(TOF)法を用いて測定核物質を非破壊測定する手法であるが、小型・高精度化には短パルスな小型中性子源が必要となる。近年発展著しいレーザー技術を用いたレー ザー駆動中性子源(LDNS)は、そのような中性子源として将来を期待されている。そこで我々はLDNSを用いたNRTAの技術開発を行い、実証実験を行った。その結果について報告する。
Lee, J.; 伊藤 史哲*; 弘中 浩太; 高橋 時音; 鈴木 敏*; 小泉 光生
Journal of Nuclear Science and Technology, 59(12), p.1546 - 1557, 2022/12
被引用回数：5 パーセンタイル：81.82(Nuclear Science & Technology)Compact time-of-flight (TOF) measurement systems are desirable for easy installation in various facilities. To achieve such compact systems, one of the key considerations is the design of the neutron moderator. However, there are only a few reports on systematic studies on moderators considering both neutron energy resolution as well as a neutron intensity. In this paper, to design an epithermal neutron moderator for short-distance TOF measurements, the neutron intensity and energy resolution of epithermal neutrons have been studied using the Monte Carlo simulation code PHITS with JENDL-4.0 for various types of moderators. The neutronic characteristics of a moderator comprising several components were evaluated. The relationships between the moderator dimensions and both the energy resolution and intensity of the epithermal neutrons were determined. From the obtained results, the appropriate high resolution moderator designs for the short-distance TOF measurements were proposed.
Lee, J.; 伊藤 史哲*; 弘中 浩太; 高橋 時音; 鈴木 敏*; 小泉 光生; 堀 順一*; 寺田 和司*
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), 4 Pages, 2022/11
中性子検出に広く使われているGS20リチウムガラスシンチレータは、応答は速いがn/g弁別能に乏しい。ガンマ線背景事象を適切に評価するためには、ガンマ線に対する応答特性を知る必要がある。特に中性子測定時は減速材中の水素原子核から発生する2.2MeVのガンマ線が主な背景事象となるが、このような高エネルギーガンマ線への応答特性の報告はほとんどない。このため、本研究では、GS20の応答特性についてNa-24ガンマ線源を用いて調べた。
