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Journal Articles

Coherent magnetization rotation of a layered system observed by polarized neutron scattering under grazing incidence geometry

Maruyama, Ryuji; Bigault, T.*; Saerbeck, T.*; Honecker, D.*; Soyama, Kazuhiko; Courtois, P.*

Crystals, 9(8), p.383_1 - 383_13, 2019/08

The in-plane magnetic structure of a layered system composed of polycrystalline grains smaller than the ferromagnetic exchange length was studied to elucidate the mechanism controlling the magnetic properties considerably different from the bulk using polarized neutron scattering under grazing incidence geometry. The measured result, together with quantitative analysis based on the distorted wave Born approximation, showed that the in-plane length of the area with uniform orientation of moments ranging from 0.5 to 1.1 $$mu$$m is not significantly varied during the process of demagnetization followed by remagnetization. The obtained behavior of moments is in good agreement with the two-dimensional random anisotropy model where coherent magnetization rotation is dominant.

Journal Articles

Effect of the interface roughness correlation on the reflectivity in a neutron multilayer mirror

Maruyama, Ryuji; Yamazaki, Dai; Soyama, Kazuhiko

JPS Conference Proceedings (Internet), 22, p.011011_1 - 011011_5, 2018/11

Neutron multilayer mirrors are one of the most important optical elements for neutron scattering experiments. Good interface quality in terms of sharpness and smoothness plays a critical role in determining the performance of optical elements. We have shown that a multilayer with a large vertical correlation length and small lateral correlation length effectively suppresses the diffuse scattering intensity. In this study, the effect of the interface roughness correlation on the neutron reflectivity of the multilayer mirror is investigated using the reflectivity calculation based on the distorted wave Born approximation.

Journal Articles

Development of high-polarization Fe/Ge neutron polarizing supermirror; Possibility of fine-tuning of scattering length density in ion beam sputtering

Maruyama, Ryuji; Yamazaki, Dai; Akutsu, Kazuhiro*; Hanashima, Takayasu*; Miyata, Noboru*; Aoki, Hiroyuki; Takeda, Masayasu; Soyama, Kazuhiko

Nuclear Instruments and Methods in Physics Research A, 888, p.70 - 78, 2018/04

 Percentile:100(Instruments & Instrumentation)

The multilayer structure of Fe/Si and Fe/Ge systems fabricated by ion beam sputtering (IBS) was investigated using X-ray and polarized neutron reflectivity measurements and scanning transmission electron microscopy with energy-dispersive X-ray analysis. The obtained result revealed that the incorporation of sputtering gas particles (Ar) in the Ge layer gives rise to a marked reduction in the neutron scattering length density (SLD) and contributes to the SLD contrast between the Fe and Ge layers almost vanishing for spin-down neutrons. This leads to a possibility of fine-tuning of the SLD for the IBS, which is required to realize a high polarization efficiency of a neutron polarizing supermirror. Fe/Ge polarizing supermirror with $$m=5$$ fabricated showed a spin-up reflectivity of 0.70 at the critical momentum transfer. The polarization was higher than 0.985 for the $$q_z$$ range where the correction for the polarization inefficiencies of the beamline works properly.

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Journal Articles

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

Neutron devices such as neutron detectors, optical devices including supermirror devices and $$^{3}$$He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

Journal Articles

Accessible length scale of the in-plane structure in polarized neutron off-specular and grazing-incidence small-angle scattering measurements

Maruyama, Ryuji; Bigault, T.*; Wildes, A. R.*; Dewhurst, C. D.*; Saerbeck, T.*; Honecker, D.*; Yamazaki, Dai; Soyama, Kazuhiko; Courtois, P.*

Journal of Physics; Conference Series, 862(1), p.012017_1 - 012017_6, 2017/06

The in-plane magnetic structure of Fe/Si multilayers with a polycrystalline grain size less than the ferromagnetic exchange length was investigated using polarized neutron off-specular scattering and grazing-incidence small-angle scattering measurements. These complementary measurements, each of them covering different length scales, together with the data analysis based on the distorted wave Born approximation, revealed lateral correlation in the fluctuating orientation of the magnetization in the layer on a sub-$$mu$$m length scale. The obtained in-plane magnetic structure is consistent with the random anisotropy model, i.e. competition between the exchange interactions between neighboring spins and the local magnetocrystalline anisotropy.

Journal Articles

Silver photo-diffusion and photo-induced macroscopic surface deformation of Ge$$_{33}$$S$$_{67}$$/Ag/Si substrate

Sakaguchi, Yoshifumi*; Asaoka, Hidehito; Uozumi, Yuki; Kondo, Keietsu; Yamazaki, Dai; Soyama, Kazuhiko; Ailavajhala, M.*; Mitkova, M.*

Journal of Applied Physics, 120(5), p.055103_1 - 055103_10, 2016/08

 Times Cited Count:5 Percentile:57.78(Physics, Applied)

Journal Articles

Processes of silver photodiffusion into Ge-chalcogenide probed by neutron reflectivity technique

Sakaguchi, Yoshifumi*; Asaoka, Hidehito; Uozumi, Yuki; Kawakita, Yukinobu; Ito, Takayoshi*; Kubota, Masato; Yamazaki, Dai; Soyama, Kazuhiko; Sheoran, G.*; Mitkova, M.*

Physica Status Solidi (A), 213(7), p.1894 - 1903, 2016/07

 Times Cited Count:5 Percentile:57.78(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Study of the in-plane magnetic structure of a layered system using polarized neutron scattering under grazing incidence geometry

Maruyama, Ryuji; Bigault, T.*; Wildes, A. R.*; Dewhurst, C. D.*; Soyama, Kazuhiko; Courtois, P.*

Nuclear Instruments and Methods in Physics Research A, 819, p.37 - 53, 2016/05

 Times Cited Count:3 Percentile:42.29(Instruments & Instrumentation)

The in-plane magnetic structure of a layered system with a polycrystalline grain size less than the ferromagnetic exchange length was investigated using polarized neutron off-specular scattering and grazing incidence small angle scattering measurements to gain insight into the mechanism that controls the magnetic properties which are different from the bulk. These complementary measurements with different length scales and the data analysis based on the distorted wave Born approximation revealed the lateral correlation on a length scale of sub-$$mu$$m due to the fluctuating orientation of the magnetization in the layer. The in-plane magnetic structure indicated by these measurements is consistent with the random anisotropy model, i.e. competition between the exchange interactions between neighboring spins and the local magnetocrystalline anisotropy.

Journal Articles

Numerical evaluation of the light transport properties of alternative He-3 neutron detectors using ceramic scintillators

Ozu, Akira; Takase, Misao*; Haruyama, Mitsuo; Kurata, Noritaka*; Kobayashi, Nozomi*; Kureta, Masatoshi; Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; et al.

Nuclear Instruments and Methods in Physics Research A, 798, p.62 - 69, 2015/10

 Times Cited Count:2 Percentile:66.76(Instruments & Instrumentation)

The light transport properties of scintillator light inside alternative He-3 neutron detector modules using scintillator sheets have been investigated by a ray-tracing simulation code. The detector module consists of a light-reflecting tube, a thin rectangular ceramic scintillator sheet laminated on a glass plate, and two photo-multiplier tubes (PMTs) mounted at both ends of the detector tube. The light induced on the surface of the scintillator sheet via nuclear interaction between the scintillator and neutrons are detected by the two PMTs. The light output of various detector modules in which the scintillator sheets are installed with several different arrangements were examined and evaluated in comparison with experimental results. The results derived from the simulation reveal that the light transport property is strongly dependent on the arrangement of the scintillator sheet inside the tube and the shape of the tube.

Journal Articles

Measurement of transient photo-induced changes in thin films at J-PARC; Time-resolved neutron reflectivity measurements of silver photo-diffusion into Ge-chalcogenide films

Sakaguchi, Yoshifumi*; Asaoka, Hidehito; Uozumi, Yuki; Kawakita, Yukinobu; Ito, Takayoshi*; Kubota, Masato; Yamazaki, Dai; Soyama, Kazuhiko; Ailavajhala, M.*; Wolf, K.*; et al.

JPS Conference Proceedings (Internet), 8, p.031023_1 - 031023_6, 2015/09

We report recent results of time-resolved neutron reflectivity measurements for silver photo-diffusion into Ge$$_{x}$$S$$_{1-x}$$ (x=0.20, 0.33, 0.40) films performed on BL17 (SHARAKU). It is well known that silver diffuses into Ge-chalcogenide layer by visible light exposure with a distinct diffusion front, where the silver concentration abruptly drops off. Using an event recording system at the Materials and Life Science Experimental Facility, neutron reflectivity profiles were collected with a time-resolution of 30 seconds in the shortest case. It was found from the measurements that a relatively stable Ag-rich phase in the reaction layer is firstly formed, and then, slower diffusion occurs at the interface between Ag-rich and Ag-poor layers. Fourier transform analysis showed that the position of the interface is essentially fixed. This result is in contrast to the previously reported model of silver diffusion that postulates a mechanism involving progression of the diffusion front. The results of the measurements on Ag/Ge-Se films performed on the INTER instrument at ISIS are also reported.

Journal Articles

Dynamics of silver photo-diffusion into Ge-chalcogenide films; Time-resolved neutron reflectometry

Sakaguchi, Yoshifumi*; Asaoka, Hidehito; Uozumi, Yuki; Kawakita, Yukinobu; Ito, Takayoshi*; Kubota, Masato; Yamazaki, Dai; Soyama, Kazuhiko; Ailavajhala, M.*; Latif, M. R.*; et al.

Journal of Physics; Conference Series, 619(1), p.012046_1 - 012046_4, 2015/06

 Times Cited Count:6 Percentile:2.73

We report the results of time-resolved neutron reflectivity measurements of Ag/a- Ge$$_{20}$$S$$_{80}$$/Si and a- Ge$$_{40}$$Se$$_{60}$$/Ag/ Si films taken while the films are exposed to visible light. Silver diffuses into an amorphous (a-) chalcogenide layer while visible light illuminates Ag/a-chalcogenide films. Neutron reflectometry is a suitable technique probing time evolution of the multi-layer structure without damaging the sample by the probe beam itself. It was found from the measurements of Ag/a-Ge$$_{20}$$S$$_{80}$$/Si films that a relatively stable Ag-rich phase in the reaction layer is first formed, and then, slower diffusion occurs at the interface between Ag-rich and Ag-poor layers. This result is in contrast to the previously reported model of silver diffusion that suggests a mechanism involving progression of the diffusion front. From the measurements of a-Ge$$_{40}$$Se$$_{60}$$/Ag/ Si films, we found enormous changes in the neutron reflectivity profile, including loss of total reflection region, with continuous illumination even after forming one homogeneous layer, which was about 60 min after starting illumination. At this stage, clear off-specular scattering was observed by a linear detector and a surface roughness was observed with naked eyes.

Journal Articles

Development of a ceramic-insulated ball-anode element for neutron detection

To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Soyama, Kazuhiko; Yamagishi, Hideshi*

Nuclear Instruments and Methods in Physics Research A, 784, p.194 - 197, 2015/06

 Times Cited Count:1 Percentile:81.41(Instruments & Instrumentation)

A novel ceramics insulated detector element was developed for neutron measurement. The developed detector element consists of a ceramics insulator, cathode lines on the insulator, and ball-shaped anodes. The incident neutrons are usually scattered by the detector element itself because it acts as scatterer. To estimate the effects of scattering, we calculated the amount of neutrons scattered by the developed element. By the calculation results by a Monte Carlo simulation using PHITS, it is found that the developed element is effective to reduce the scattered neutrons. The number of scattered neutrons of the developed element is 40% smaller than that of polymer insulated element, which is widely used in micro-pattern element. Finally, neutron-induced signals were clearly observed using the developed detector element.

JAEA Reports

Characterization of NiC/Ti supermirror deposited on a metallic substrate

Tamura, Itaru; Kashima, Yoichi; Soyama, Kazuhiko

JAEA-Research 2014-029, 12 Pages, 2015/03

JAEA-Research-2014-029.pdf:1.89MB

Neutron guide tubes, which are installed near reactor cores, are damaged by neutrons and $$gamma$$ rays irradiation. Those glass substrates which contain boron material are affected by (n, $$alpha$$) reaction, and ionization effect of $$gamma$$ rays on material strength decrease duration of use of neutron guide tubes. In order to increase resistance to radiation, we have fabricated a supermirror with Ni-P metallic substrate. The substrate roughness with 0.2 - 0.3 nm (rms) was produced by super- polishing. The neutron reflectivity reached 76 % for an m=3 supermirror.

Journal Articles

JAEA-ISCN development programs of advanced NDA technologies of nuclear material

Seya, Michio; Kobayashi, Naoki; Naoi, Yosuke; Hajima, Ryoichi; Soyama, Kazuhiko; Kureta, Masatoshi; Nakamura, Hironobu; Harada, Hideo

Book of Abstracts, Presentations and Papers of Symposium on International Safeguards; Linking Strategy, Implementation and People (Internet), 8 Pages, 2015/03

JAEA-ISCN has been implementing basic development programs of the advanced NDA technologies for nuclear material (NM) since 2011JFY (Japanese Fiscal Year), which are (1) NRF (Nuclear resonance fluorescence) NDA technology using laser Compton scattered (LCS) $$gamma$$-rays (intense mono-energetic $$gamma$$-rays), (2) Alternative to $$^{3}$$He neutron detection technology using ZnS/B$$_{2}$$O$$_{3}$$ ceramic scintillator, and (3) NRD (Neutron resonance densitometry) using NRTA (Neutron resonance transmission analysis) and NRCA (Neutron resonance capture analysis). These programs are going to be finished in 2014JFY and have demonstration tests in February - March 2015.

Journal Articles

Basic technology development of advanced non-destructive detection / Measurement of nuclear material for nuclear security and nuclear nonproliferation

Seya, Michio; Naoi, Yosuke; Kobayashi, Naoki; Nakamura, Takahisa; Hajima, Ryoichi; Soyama, Kazuhiko; Kureta, Masatoshi; Nakamura, Hironobu; Harada, Hideo

Kaku Busshitsu Kanri Gakkai (INMM) Nippon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/01

The Integrated Support Center for Nuclear Non-proliferation and Nuclear Security (ISCN) of Japan Atomic Energy Agency (JAEA) has been conducting (based on collaborations with JAEA other centers) the following basic technology development programs of advanced non-destructive detection/measurement of nuclear material for nuclear security and nuclear non-proliferation. (1) The demonstration test of the Pu-NDA system for spent fuel assembly using PNAR and SINRD (JAEA/USDOE(LANL) collaboration, completed in JFY2013), (2) Basic development of NDA technologies using laser Compton scattered $$gamma$$-rays (Demonstration of an intense mono-energetic $$gamma$$-ray source), (3) Development of alternative to He-3 neutron detection technology, (4) Development of neutron resonance densitometry (JAEA/JRC collaboration)This paper introduces above programs.

Journal Articles

Evaluation of two-dimensional multiwire neutron detector with individual line readout under pulsed neutron irradiation

To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Soyama, Kazuhiko; Yamagishi, Hideshi*

Journal of Instrumentation (Internet), 9(11), p.C11019_1 - C11019_9, 2014/11

 Percentile:100(Instruments & Instrumentation)

A multiwire-type two-dimensional neutron detector system using individual line readout and optical signal transmission method is developed for use in the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC). The sensitive area was 128 $$times$$ 128 mm$$^{2}$$ with a pitch of 1 mm in both directions (x and y), and the 256 signal lines are individually readout by signal-processing electronics. First irradiation experiments using pulsed neutrons are performed at the J-PARC/MLF. The developed detector could determine time-of-flight spectra and time-resolved two-dimensional images accurately with time range from 0 to 40 ms that arise from 25-Hz pulsed neutrons. Finally, the validity of the detector system is confirmed by a neutron reflectometry using Ni/Ti multilayer.

Journal Articles

Studies of silver photo diffusion dynamics in Ag/Ge$$_{x}$$S$$_{1-x}$$ ($$x$$=0.2 and 0.4) films using neutron reflectometry

Sakaguchi, Yoshifumi*; Asaoka, Hidehito; Uozumi, Yuki; Kawakita, Yukinobu; Ito, Takayoshi*; Kubota, Masato; Yamazaki, Dai; Soyama, Kazuhiko; Ailavajhala, M.*; Latif, R.*; et al.

Canadian Journal of Physics, 92(7/8), p.654 - 658, 2014/07

 Times Cited Count:9 Percentile:35.7(Physics, Multidisciplinary)

We report our recent results of neutron reflectivity measurements for Ag/a-Ge $$_{x}$$S$$_{1-x}$$ (x=0.2, 0.4) films under light illumination. The neutron reflectivity measurements have been performed on a polarized neutron reflectometer (BL17, SHARAKU) at Japan Proton Accelerator Research Complex (J-PARC), Japan. By using the time-of flight instrument with intensive pulsed neutrons produced by 300kW proton beams, time evolution of the neutron reflectivity under a light illumination has been revealed, with at least 2-min time resolution. From the detailed analysis, it was found for Ag 50nm/Ge $$_{40}$$S $$_{60}$$ 150nm films under a light illumination from the Ag layer side that there are two types of diffusion processes: a fast change observed in the first 10 min after illumination using a xenon lamp, which is then followed by a slow change observed after a 1 hour of additional light exposure. The result indicates that there is a comparatively stable (metastable) state in the Ag-doped Ge $$_{40}$$S $$_{60}$$ layer in terms of Ag composition, and the next silver diffusion process occurs by affecting the Ag-doped Ge $$_{40}$$S $$_{60}$$ layer / interface. This coincides with the Ge $$_{40}$$S $$_{60}$$ results of Wagner et al. obtained for Ag/As-S films. These results are also in accord with the results reported by some of us by modeling of the Ag transport in Ge-Se glass showing the presence of slow and fast moving Ag ions. Our result demonstrated that the idea of a two-step reaction process can be applied to Ge-chalcogenide system. We also discuss illumination-side dependence and Ge-composition dependence of reaction process.

Journal Articles

Development of a compact vertical splitting system for the cold neutron beam at JRR-3

Tamura, Itaru; Maruyama, Ryuji; Yamazaki, Dai; Nakamura, Kiyoshi; Yamamoto, Kazuyoshi; Aizawa, Kazuya; Soyama, Kazuhiko

Journal of Physics; Conference Series, 528, p.012012_1 - 012012_7, 2014/07

 Percentile:100

To achieve efficient implementation of usage of neutron beam instruments, the instruments were rearranged at C2 cold neutron beam line at JRR-3 by using a newly developed compact vertical splitting system. The splitting system has two compact multi channel benders. The bender has been developed using Ni/Ti supermirrors coated on both sides of 0.2 mm thickness silicon substrates. The curvature radius of the bender is 938 mm and the length of the bender is 320 mm yielding deflection angles of 20$$^{circ}$$. Supermirrors with m=3 were deposited on both sides of silicon substrate by an ion beam sputtering apparatus in JAEA. Neutron flux at the end of the neutron guide that installed at the bender exit of which the deflection angle is 20$$^{circ}$$ was measured by the gold foil activation method. It was measured 1.58 $$times$$ 10$$^{7}$$ n/cm$$^{2}$$/s. The present study showed that the supermirrors coated on both sides with high reflectivity are suitable for the compact bender.

Journal Articles

Performance evaluation of high-pressure MWPC with individual line readout under Cf-252 neutron irradiation

To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Soyama, Kazuhiko; Yamagishi, Hideshi*

Journal of Physics; Conference Series, 528, p.012045_1 - 012045_6, 2014/07

 Times Cited Count:1 Percentile:34.99

A multiwire proportional chamber (MWPC) neutron detector system is developed for use in the Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex. In the developed MWPC system, a short response time and high spatial resolution can be obtained through the use of an individual line readout method. The developed system consists of a 256 channel detector element (x: 128 lines, y: 128 lines) equipped with a pressure vessel, amplifier-shaper-discriminator (ASD) boards, optical signal transmission devices, position encoders with field-programmable gate arrays (FPGAs), and a data acquisition device. The measured uniformity of all pixels in the two-dimensional image was 7.9%. The average intrinsic spatial resolution was 1.55 mm full width at half-maximum in the sensitive region calculated by taking into account measured track lengths of secondary particles.

305 (Records 1-20 displayed on this page)