粘土を含む水が花崗岩質岩盤の透水特性に及ぼす影響

奈良 禎太*; 柏谷 公希*; 桶谷 和生*; 藤井 宏和*; Zhao, Y.*; 加藤 昌治*; 青柳 和平; 尾崎 裕介; 松井 裕哉; 河野 勝宣*

材料, 73(3), p.220 - 225, 2024/03

https://doi.org/10.2472/jsms.73.220

岩盤中においては、その中に含まれる亀裂が地下水流動や物質移動の主な移行経路となる。このような亀裂に粘土鉱物のような微細な粒子が充填すると、岩盤の透水係数が低下することが室内試験により確認されている。本研究では原位置においても同様の現象が発生するかを確認するため、瑞浪用地の深度300mにおいて岩盤中に粘土を含む水を注入し、岩盤の透水性の変化を測定した。原位置試験では粘土を含む水の注入により、2オーダーの透水性の低下が確認され、原位置においても粘土鉱物のような粒子の亀裂の充填により透水性が低下することが確認された。

Acoustically driven magnon-phonon coupling in a layered antiferromagnet

Lyons, T. P.*; Puebla, J.*; 山本 慧; Deacon, R. S.*; Hwang, Y.*; 石橋 幸治*; 前川 禎通*; 大谷 義近*

Physical Review Letters, 131(19), p.196701_1 - 196701_6, 2023/11

https://doi.org/10.1103/PhysRevLett.131.196701

Harnessing the causal relationships between mechanical and magnetic properties of van der Waals materials presents a wealth of untapped opportunity for scientific and technological advancement, from precision sensing to novel memories. This can, however, only be exploited if the means exist to efficiently interface with the magnetoelastic interaction. Here, we demonstrate acoustically-driven spin-wave resonance in a crystalline antiferromagnet, chromium trichloride, via surface acoustic wave irradiation. The resulting magnon-phonon coupling is found to depend strongly on sample temperature and external magnetic field orientation, and displays a high sensitivity to extremely weak magnetic anisotropy fields in the few mT range. Our work demonstrates a natural pairing between power-efficient strain-wave technology and the excellent mechanical properties of van der Waals materials, representing a foothold towards widespread future adoption of dynamic magneto-acoustics.

Present status of J-PARC MUSE

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

https://doi.org/10.1088/1742-6596/2462/1/012033

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.

Perspectives on spintronics with surface acoustic waves

Puebla, J.*; Hwang, Y.*; 前川 禎通*; 大谷 義近*

Applied Physics Letters, 120(22), p.220502_1 - 220502_9, 2022/05

https://doi.org/10.1063/5.0093654

Surface acoustic waves (SAWs) are elastic waves propagating on the surface of solids with the amplitude decaying into the solid. The well- established fabrication of compact SAW devices, together with well-defined resonance frequencies, places SAWs as an attractive route to manipulate the magnetization states in spintronics, all of which is made possible by the magnetostriction and magnetoelastic effects. Here, we review the basic characteristics of SAW devices and their interaction out-of-resonance and in-resonance with the magnetization in thin films. We describe our own recent results in this research field and closely related works and provide our perspectives moving forward.

Phase space formation of high intensity 60 and 80 mA H beam with orifice in J-PARC front-end

柴田 崇統*; 池上 清*; 南茂 今朝雄*; Liu, Y.*; 大谷 将士*; 内藤 富士雄*; 神藤 勝啓; 大越 清紀; 岡部 晃大; 近藤 恭弘; et al.

JPS Conference Proceedings (Internet), 33, p.011010_1 - 011010_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011010

J-PARC初段加速部では、イオン源から引き出されるビーム大強度化とともに、高周波四重極リニアック(RFQ)のビーム透過率向上が重要な課題である。RFQ透過率は、イオン源とRFQ間に位置する低エネルギービーム輸送部(LEBT)内のソレノイド電磁石設定に大きく依存する。本研究では、大強度化を行った際のRFQ透過率が高いビーム条件を明らかにするため、テストスタンドにおいてLEBT内で72mAと88mAの大強度ビーム下において、RFQ入口でのビーム粒子の位相空間分布を測定し、シミュレーションによる解析結果と比較した。その結果、LEBT内で水素ガスの差動排気に用いられる15mmオリフィスにビームが衝突してコリメートされることで、RFQ入口におけるエミッタンスおよびTwissパラメータに影響することが判った。特に、ビーム電流88mAの条件では、この機構を利用することで、低ソレノイド電流値でRFQ透過率が最適となる結果が見られた。ビーム大強度化に伴い、空間電荷効果を抑えるために必要なソレノイド電流が設計上限に至る懸念があったが、本研究からコリメートビームの利用で問題解決の可能性が示された。

Measurement of Doppler broadening of prompt gamma-rays from various zirconium- and ferro-borons

土川 雄介; 甲斐 哲也; 阿部 雄太; 大石 佑治*; Sun, Y.*; 及川 健一; 中谷 健; 佐藤 一憲

Nuclear Instruments and Methods in Physics Research A, 991, p.164964_1 - 164964_5, 2021/03

https://doi.org/10.1016/j.nima.2020.164964

福島第一原子力発電所の廃炉に伴い、建屋内部に残留するホウ素やホウ化物の定量分析、及びホウ素化合状態の同定が一つの重要な調査項目となっている。本件では、ホウ化ジルコニウム,ホウ化鉄,純ホウ素及びその他のホウ化物に中性子を照射することで発生する478keV即発ガンマ線のエネルギー幅を測定し、ホウ化物毎に異なるドップラー幅を用いた化合物の同定可能性を調査した。金属,非金属ホウ化物ではそれらの即発ガンマ線ドップラー幅に顕著な違いが見られた一方で、ホウ化ジルコニウムとホウ化鉄では幅の違いが微小であった。ガンマ線エネルギースペクトル解析でこれら金属ホウ化物の違いを詳細に測定し評価した。

The Energy-resolved neutron imaging system, RADEN

篠原 武尚; 甲斐 哲也; 及川 健一; 中谷 健; 瀬川 麻里子; 廣井 孝介; Su, Y. H.; 大井 元貴; 原田 正英; 飯倉 寛; et al.

Review of Scientific Instruments, 91(4), p.043302_1 - 043302_20, 2020/04

https://doi.org/10.1063/1.5136034

The energy-resolved neutron imaging system, RADEN, has been installed at the pulsed neutron source in the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. In addition to conventional neutron radiography and tomography, RADEN, the world's first imaging beam-line at a pulsed neutron source, provides three main options for new, quantitative neutron imaging techniques: Bragg-edge imaging to visualize the spatial distribution of crystallographic information, resonance absorption imaging for elemental composition and temperature information, and polarized neutron imaging for magnetic field information. This paper describes the results of characterization studies of the neutronic performance and installed devices at RADEN and shows the results of several demonstration studies for pulsed neutron imaging.

Energy measurement and correction for stable operation in J-PARC

守屋 克洋; 原田 寛之; Liu, Y.*; 大谷 将士*

Journal of Physics; Conference Series, 1350, p.012140_1 - 012140_5, 2019/11

https://doi.org/10.1088/1742-6596/1350/1/012140

In Japan Proton Accelerator Research Complex (J-PARC), the beam accelerated up to 400 MeV in the Linac is injected to 3 GeV rapid cycling synchrotron (RCS), and we realize the high intensity beam by using multi-turn injection. During user operation, we rarely detected the beam loss at the high dispersion area in the RCS or the beam collimator section in the extraction beam transport line. These incidents indicate that the beam loss is caused by the momentum shift of RCS injection beam according to the experimental and simulation results. In the beam commissioning, we check the Linac beam momentum just before the user operation of the RCS. However, we could not previously measure the Linac beam momentum during the user operation because we adopt the multi-turn injection and the injected beam momentum was changed by the synchrotron oscillation in longitudinal plane. Therefore, we measured the beam momentum at the beam injection line of the RCS. Because the Linac-to-3-GeV-RCS Beam Transport line (L3BT) has the high dispersion areas, we estimated the injection beam momentum from the beam orbit data by the Beam Position Monitors (BPMs). We measured the beam position data and estimated the momentum shift by using the data and beam simulation. As a result, we found the momentum fluctuation during the user operation and the fluctuation width was up to 0.1%. To suppress the beam loss induced by the momentum fluctuation, we developed the momentum correction system. The fluctuation was suppressed less than 0.02% with this system. Finally, the beam loss incidents induced by the beam momentum shift no longer occur, and we successfully achieved the more stable user operation in J-PARC.

Spatial resolution test targets made of gadolinium and gold for conventional and resonance neutron imaging

瀬川 麻里子; 及川 健一; 甲斐 哲也; 篠原 武尚; 林田 洋寿*; 松本 吉弘*; Parker, J. D.*; 中谷 健; 廣井 孝介; Su, Y. H.; et al.

JPS Conference Proceedings (Internet), 22, p.011028_1 - 011028_8, 2018/11

https://doi.org/10.7566/JPSCP.22.011028

We have fabricated and utilized spatial resolution test targets made of gadolinium and gold for conventional and resonance neutron imaging performed at RADEN, located at beam line BL22 of the J-PARC Materials and Life Science Experimental Facility (MLF). RADEN covers a broad energy range from cold neutrons to high-energy neutrons with energy of several tens keV and was designed to perform energy-resolved neutron imaging utilizing two-dimensional detectors combined with the accurate measurement of neutron energy by the time-of-flight method. The test targets were designed to verify the spatial resolution and image uniformity of two kinds of neutron detectors, counting-type detectors and camera-type detectors. In this presentation, we report the details of these two-dimensional test targets, and the results of demonstrations using the test targets with our neutron imaging detectors. This work was supported in part by the Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Simulation, measurement, and mitigation of beam instability caused by the kicker impedance in the 3-GeV rapid cycling synchrotron at the Japan Proton Accelerator Research Complex

Saha, P. K.; 菖蒲田 義博; 發知 英明; 原田 寛之; 林 直樹; 金正 倫計; 田村 文彦; 谷 教夫; 山本 昌亘; 渡辺 泰広; et al.

Physical Review Accelerators and Beams (Internet), 21(2), p.024203_1 - 024203_20, 2018/02

AA2017-0659.pdf:3.34MB

https://doi.org/10.1103/PhysRevAccelBeams.21.024203

The transverse impedance of the extraction kicker magnets in the 3-GeV RCS of J-PARC is a strong beam instability source and it is one of the significant issue to realize 1 MW beam power as practical measures are yet to be implemented to reduce the impedance. In the present research realistic simulation by updating the simulation code to cope with all time dependent machine parameters were performed in order to study the detail of beam instability nature and to determine realistic parameters for beam instability mitigation. The simulation results were well reproduced by the measurements, and as a consequence an acceleration to 1 MW beam power has also been successfully demonstrated. To further increase of the RCS beam power up to 1.5 MW, beam instability issues and corresponding measures have also been studied.