奥平 琢也; 奥 隆之; 猪野 隆*; 林田 洋寿*; 吉良 弘*; 酒井 健二; 廣井 孝介; 高橋 慎吾*; 相澤 一也; 遠藤 仁*; et al.
Nuclear Instruments and Methods in Physics Research A, 977, p.164301_1 - 164301_8, 2020/10
We are developing a neutron polarizer with polarized He gas, referred to as a He spin filter, based on the Spin Exchange Optical Pumping (SEOP) for polarized neutron scattering experiments at Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC). A He gas-filling station was constructed at J-PARC, and several He cells with long spin relaxation times have been fabricated using the gas-filling station. A laboratory has been prepared in the MLF beam hall for polarizing He cells, and compact pumping systems with laser powers of 30 W and 110 W, which can be installed onto a neutron beamline, have been developed. A He polarization of 85% was achieved at a neutron beamline by using the pumping system with the 110 W laser. Recently, the first user experiment utilizing the He spin filter was conducted, and there have been several more since then. The development and utilization of He spin filters at MLF of J-PARC are reported.
Vu, TheDang; 西村 和真*; 宍戸 寛明*; 原田 正英; 及川 健一; 宮嶋 茂之*; 日高 睦夫*; 奥 隆之; 曽山 和彦; 相澤 一也; et al.
Journal of Physics; Conference Series, 1590, p.012036_1 - 012036_9, 2020/07
Our CB-KID neutron imager detects high spatial resolution neutrons transmission images by using a delay-line technique. We found that the number of events was remarkably increased with increasing the detector temperature until close to the critical temperature Tc. We investigated the properties of CB-KID at near Tc. We observed systematic changes of neutron signals as a function of the detector temperature from 4 K to Tc. The simulations modeled the sequential physical processes for B(n,)Li reactions and energy deposition by particles within CB-KID, including neutrons, He particles, Li particles, photon and electron transport.
Harjo, S.; 相澤 一也; Gong, W.*; 川崎 卓郎
Materials Transactions, 61(5), p.828 - 832, 2020/04
In situ neutron diffraction measurements during compressive and tensile tests of an as-cast MgZnY alloy consisting of phase (Mg) as the matrix and a long period stacking ordered phase (LPSO) of 25 vol%, were performed to understand deformation behavior of each phase and to monitor the occurrence of kinking during deformation. The LPSO grains yielded possibly via kinking during compressive deformation above the applied true stress of about 137 MPa. The stress partitioning among Mg grains was observed larger in the compressive deformation than in the tensile deformation, that might be due to the large load sharing of Mg grains as a result of the yielding of LPSO grains during compressive deformation.
Kim, J.*; 山中 暁*; 村山 一郎*; 加藤 孝典*; 坂本 友和*; 川崎 卓郎; 福田 竜生; 関野 徹*; 中山 忠親*; 武田 雅敏*; et al.
Sustainable Energy & Fuels (Internet), 4(3), p.1143 - 1149, 2020/03
Waste heat is a potentially exploitable energy source but remains a problem awaiting a solution. To explore solutions for automobile applications, we investigate pyroelectric power generation from the temperature variation of exhaust gas using a novel electro-thermodynamic cycle. Niobium-doped lead zirconate titanate stannate (PNZST) ceramics were applied as pyroelectric materials, and their structural characteristics were investigated. In the driving cycle assessments (JC-08) using real exhaust gas, the maximum power generated was identified as 143.9 mW cm (777.3 J L per 1 cycle) over a temperature range of 150-220 C and an electric field of 13 kV cm-1. The net mean generating power of the total driving cycle was 40.8 mW cm, which is the most enhanced result in our power generating systems to date and 314 times greater than our first report. Materials with sharp transition behaviors with the temperature and electric field are worthy of study with regard to pyroelectric energy harvesting materials, and their corresponding crystal and domain structures were investigated to optimize performance.
Malins, A.; 町田 昌彦; Vu, TheDang; 相澤 一也; 石田 武和*
Nuclear Instruments and Methods in Physics Research A, 953, p.163130_1 - 163130_7, 2020/02
Radiation transport simulations were used to analyse neutron imaging with the current-biased kinetic inductance detector (CB-KID). The PHITS Monte Carlo code was applied for simulating neutron, He, Li, photon and electron transport, B(n,)Li reactions, and energy deposition by particles within CB-KID. Slight blurring in simulated CB-KID images originated He and Li ions spreading out in random directions from the B conversion layer in the detector prior to causing signals in the and superconducting Nb nanowire meander lines. 478 keV prompt gamma rays emitted by Li nuclei from neutron-B reactions had negligible contribution to the simulated CB-KID images. Simulated neutron images of B dot arrays indicate that sub 10 m resolution imaging should be feasible with the current CB-KID design. The effect of the geometrical structure of CB-KID on the intrinsic detection efficiency was calculated from the simulations. An analytical equation was then developed to approximate this contribution to the detection efficiency. Detection efficiencies calculated in this study are upper bounds for the reality as the effects of detector temperature, the bias current, signal processing and dead-time losses were not taken into account. The modelling strategies employed in this study could be used to evaluate modifications to the CB-KID design prior to actual fabrication and testing, conveying a time and cost saving.
奥平 琢也; 奥 隆之; 酒井 健二; 猪野 隆*; 林田 洋寿*; 廣井 孝介; 篠原 武尚; 加倉井 和久*; 相澤 一也; 清水 裕彦*; et al.
Proceedings of Science (Internet), 356, 5 Pages, 2019/12
Vu, TheDang; 飯澤 侑貴*; 西村 和真*; 宍戸 寛明*; 小嶋 健児*; 及川 健一; 原田 正英; 宮嶋 茂之*; 日高 睦夫*; 奥 隆之; et al.
Journal of Physics; Conference Series, 1293, p.012051_1 - 012051_9, 2019/10
We succeeded in designed and fabricated a neutron detector by using a superconducting current-biased kinetic inductance detector (CB-KID), which is constructed by two perpendicular Nb-based superconducting meander-lines and an enriched B neutron conversion layer. We rebuilt completely a neutron image of a B dot array contain in the stainless-steel mesh. To improve the resolution of neutron images, the characteristics of a superconducting neutron detector have been studied carefully. In this study, we present the dependence of neutron signals in the temperature of detector. We found that when the temperature of a neutron detector is as close as the critical temperature of superconductivity, the intensity of signal increase as a function of temperature. We consider that the ratio of noise and signal is decrease which is very useful to improve the resolution of neutron images.
阿部 淳*; 関根 孝太郎*; Harjo, S.; 川崎 卓郎; 相澤 一也
Physica B; Condensed Matter, 551, p.283 - 286, 2018/12
Our previous neutron diffraction measurements investigated strain accumulation mechanism(s) in rock materials under uniaxial compression. This technique, when applied to metallic materials, is suffered by surface effects, gauge volume size effects, and/or incident beam divergence that induce pseudo-strain. Knowledge of the pseudo-strain is therefore necessary for precise evaluation of strain value in a stressed rock material. This work investigated the effects of gauge volume and incident neutron beam divergence on pseudo-strain in rock materials via neutron diffraction experiments performed on three types of sandstone. Spurious peak shifts appeared depending on the gauge volume or incident neutron beam divergence. These peak shifts were inferred to be derived from the difference between a neutron-weighted center of gravity position and a geometric center of the gauge volume position. However, changing the gauge volume height did not cause shift in the peak position.
川崎 卓郎; 稲村 泰弘; 伊藤 崇芳*; 中谷 健; Harjo, S.; Gong, W.*; 相澤 一也
Journal of Applied Crystallography, 51(3), p.630 - 634, 2018/06
A time-resolved time-of-flight neutron diffraction technique to characterize the structural properties of materials during cyclic tests has been developed. By adopting the developed technique, the behaviors of the crystal lattice and domains of the piezoelectric material in a multilayer-type piezoelectric actuator driven by a cyclic electric field were evaluated. The variation in diffraction intensity during the application of a cyclic electric field was obtained successfully, and the hysteresis-like behaviors of both the lattice strain and the 90 domain switching were revealed.
徐 平光; Harjo, S.; 小島 真由美*; 鈴木 裕士; 伊藤 崇芳*; Gong, W.; Vogel, S. C.*; 井上 純哉*; 友田 陽*; 相澤 一也; et al.
Journal of Applied Crystallography, 51(3), p.746 - 760, 2018/06
Neutron diffraction texture measurements provide bulk textures with excellent grain statistics even for large grained materials, together with the crystallographic parameters and microstructure information such as phase fractions, coherent crystallite size, root mean square microstrain, macroscopic/intergranular stress/strain. The procedure for high stereographic resolution texture and residual stress evaluation was established at the TAKUMI engineering materials diffractometer. The pole figure evaluation of a limestone standard sample with a trigonal crystal structure suggested that the obtained precision for texture measurement is comparable with the oversea well-established neutron beam lines utilized for texture measurements. A high strength martensite-austenite multilayered steel was employed for further verification of the reliability of simultaneous Rietveld analysis of multiphase textures and macro stress tensors. By using a geometric mean micro-mechanical model, the macro stress tensor analysis with a plane stress assumption showed a RD-TD in-plane compressive stress (about -330 MPa) in martensite layers and a RD-TD in-plane tensile stress (about 320 MPa) in austenite layers. The phase stress partitioning was ascribed to the additive effect of volume expansion during martensite transformation and the linear contraction misfit during water quenching.
梶本 亮一; 中村 充孝; 稲村 泰弘; 蒲沢 和也*; 池内 和彦*; 飯田 一樹*; 石角 元志*; 村井 直樹; 吉良 弘*; 中谷 健; et al.
Journal of Physics; Conference Series, 1021(1), p.012030_1 - 012030_6, 2018/06
4SEASONS is a medium-resolution thermal neutron chopper spectrometer in the Materials and Life Science Experimental Facility (MLF) at J-PARC. Although 4SEASONS is routinely used for many experiments by internal and external users, upgrading and maintenance work is still underway. This paper reviews the recent improvements of the instrument.
中島 健次; 川北 至信; 伊藤 晋一*; 阿部 淳*; 相澤 一也; 青木 裕之; 遠藤 仁*; 藤田 全基*; 舟越 賢一*; Gong, W.*; et al.
Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12
Harjo, S.; 川崎 卓郎; 友田 陽*; Gong, W.*; 相澤 一也; Tichy, G.*; Shi, Z.*; Ungar, T.*
Metallurgical and Materials Transactions A, 48(9), p.4080 - 4092, 2017/09
neutron diffraction during tensile deformation of lath martensite steel containing 0.22 mass% of carbon, is performed using TAKUMI of J-PARC. The diffraction peaks at plastically deformed states exhibit asymmetries as the reflection of redistributions of the stress and dislocation densities/arrangements in lath-packets where the dislocation glides are favorable (soft packet) and unfavorable (hard packet). The dislocation density is as high as 10 m at the as-quenched state, and then during tensile straining, the load and the dislocation density become different between the two lath-packets. The dislocation character and arrangement vary also in the hard packet, but hardly change in the soft packet. The hard packet plays an important role in the high work hardening in martensite, which could be understood by taking into account not only the increase of the dislocation density but also the change in dislocation arrangement.
坂佐井 馨; 佐藤 節夫*; 瀬谷 智洋*; 中村 龍也; 藤 健太郎; 山岸 秀志*; 曽山 和彦; 山崎 大; 丸山 龍治; 奥 隆之; et al.
Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09
辺見 努*; Harjo, S.; 梶谷 秀樹*; 諏訪 友音*; 齊藤 徹*; 相澤 一也; 長村 光造*; 小泉 徳潔*
IEEE Transactions on Applied Superconductivity, 27(4), p.4200905_1 - 4200905_5, 2017/06
The superconducting property of NbSn strands is very sensitive to strain. The transverse electromagnetic loading has been considered as a major origin of the degradation of NbSn cable-in-conduit conductors (CICCs) due to the local bending. Since the bending pitch is around 5 mm due to contacting of strands compacted by the electromagnetic transverse loading, there is a possibility of a large bending strain with small deflection of strands. The bending strain of the strands cannot be evaluated from only the small deflection obtained visually. Measuring bending strain of NbSn strand in CICCs is important for evaluating the conductor performance. Neutrons, which have a large penetration depth, are a powerful tool to evaluate the internal strain of NbSn in the CICC. This paper shows that the bending strain in NbSn strands of CICCs can be determined by the neutron diffraction profile nondestructively and quantitatively.
川崎 卓郎; Harjo, S.; Gong, W.; 相澤 一也
Journal of Physics; Conference Series, 746(1), p.012044_1 - 012044_6, 2016/10
The microstructure of the metallic material is widely investigated in order to understand mechanical properties of the material by line profile analysis for X-ray and neutron diffraction data. Neutron diffraction has an advantage for obtaining averaged information of the microstructure inside the bulky material owing to its high transmittance. Further, the variation of the microstructure in the material during mechanical process is able to be observed by in-situ measurements. The Convolutional Multiple Whole Profile (CMWP) fitting method is a state of the art technique for line profile analysis. The dislocation characteristics are evaluated from the shape of the peak profile including the tail by this technique. In this study, the dislocation characteristics in martensitic steels during tensile deformation were studied by in-situ neutron diffraction measurement using the Engineering Materials Diffractometer TAKUMI at J-PARC through line profile analysis using the CMWP fitting method.
Harjo, S.; 川崎 卓郎; Gong, W.; 相澤 一也
Journal of Physics; Conference Series, 746(1), p.012046_1 - 012046_7, 2016/10
In situ neutron diffraction during tensile deformation of an as-quenched lath martensitic 22SiMn2TiB steel, was performed using a high resolution and high intensity time-offlight neutron diffractometer. The characterizations of dislocations were analyzed using the classical Williamson-Hall (cWH) and modified Williamson-Hall (mWH) plots on the breadth method, and the convolutional multiple whole profile (CMWP) fitting method. As results, the dislocation density as high as 10 m in the as-quenched martensitic steel was determined. The dislocation density was found to decrease qualitatively with plastic deformation by the cWH and mWH plots, but hardly to change by the CMWP method. The scanning transmission electron microscopy observation supported the results of the latter method. In the CMWP method, the parameter that represents the arrangement of dislocations was found to decrease rapidly where a very high work hardening was observed.
梶本 亮一; 中村 充孝; 稲村 泰弘; 蒲沢 和也*; 池内 和彦*; 飯田 一樹*; 石角 元志*; 中島 健次; 河村 聖子; 中谷 健; et al.
JAEA-Conf 2015-002, p.319 - 329, 2016/02
4SEASONS () is one of the three chopper spectrometers operating in MLF at J-PARC, and covers thermal neutron region ( - meV) with relaxed resolution and high flux. The repetition rate multiplication by the Fermi chopper on this short length (18 m between the source and the sample) spectrometer enables wide-band multiple-incident-energy (multi-) measurements, which proved to be useful in observing hierarchical structures in excitations over a large energy scale. On the other hand, the upgrading work of the spectrometer has been continued since the first inelastic scattering experiment in 2009. For examples, we took several measures to suppress background, installed new detectors recently, and are developing a new Fermi chopper now. In the presentation, we show examples of scientific outputs from the spectrometer which benefit from the multi- measurements, and recent or planned upgrades of the instrument.
川崎 卓郎; Harjo, S.; Gong, W.; 相澤 一也; 岩橋 孝明; Shi, Z.*; Li, J.*; 友田 陽*; Ungr, T.*
JPS Conference Proceedings (Internet), 8, p.031009_1 - 031009_5, 2015/09
Harjo, S.; 川崎 卓郎; 辺見 努; 伊藤 崇芳*; 中本 建志*; 相澤 一也
JPS Conference Proceedings (Internet), 8, p.031001_1 - 031001_5, 2015/09
Measurements of thermal strains in the superconducting constituent (NbSn phase) in NbSn strand were performed using BL19 Takumi of MLF, J-PARC. Lattice parameters of NbSn phase change continuously with increasing temperature. To avoid the thermal expansion effect, lattice parameters of the filaments (extracted from the strand) measured at the same temperatures were used to estimate the thermal strains in NbSn phase. As results, thermal strains for axial direction below 50 K are kept roughly constant at large compressive values, while the values are much lower (the difference is 0.13%) than that measured at room temperature.