Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
及川 健一; 渡辺 賢一*; 鬼柳 善明*; 佐藤 博隆*; 伊藤 正和*; Parker, J. D.*; 篠原 武尚
no journal, ,
Japanese swords, which have a history of about 1000 years, are interesting not only for their function as weapons and their lean beauty, but also for their advanced steel processing technology. In particular, the details of the manufacturing methods of Japanese swords before the 16th century are unknown due to oral tradition, and various destructive tests have been conducted until around the 1980s. In 1985, Takahashi et al. examined four Japanese sword cuttings from the Northern and Southern Dynasties and the early Edo Periods, and reported the macro- and microstructure, chemical composition, inclusions, and Vickers hardness distribution of the cross sections. In 2017, we conducted a neutron diffraction experiment on the same four-striped piece at Takumi at J-PARC, and clarified the differences in the distribution of carbon content in iron, as well as the distribution of crystallite size and dislocation density by Rietveld analysis and line-broadening analysis. In this study, we performed a Bragg edge imaging experiment on the same sample at RADEN at J-PARC to obtain information on the crystalline structure and the real space distribution of Vickers hardness obtained from the edge width. The details of the analysis results will be presented.
measurements on chopper spectrometers中島 健次; 菊地 龍弥*; 河村 聖子
no journal, ,
パルス中性子源におけるチョッパー型分光器における、RRMベースの多重測定において、飛行時間図で介在する軌道を許可することにより選択可能なの範囲を広げる方法について、その検討を報告する。測定の最適化と一般化された定式化された条件を検討し、既存の分光器を含めたチョッパー型分光器への新たな設計基準としての導入を提案する。
=1/2 honeycomb antiferromagnet, 
-RuCl
中島 健次; 児島 佑樹*; 栗田 伸之*; 田中 秀数*
no journal, ,
中性子散乱を用いた-RuClの磁気励起の特に低エネルギー側の精密測定結果について報告する。-RuClの磁気励起に関する中性子散乱以外も含めた実験の報告や理論的な議論と比較し、我々の実験で得られた磁気励起の微細な構造やその温度変化について考察することで、この系におけるKitaev模型の実現を探る。
大原 高志; 鬼柳 亮嗣; 中尾 朗子*; 宗像 孝司*; 石川 喜久*; 森山 健太郎*; 田村 格良; 金子 耕士
no journal, ,
SENJU at J-PARC is a time-of-flight (TOF) single-crystal neutron diffractometer designed for precise crystal and magnetic structure analyses under multiple extreme environments, such as low-temperature, high-pressure and high-magnetic field, as well as for taking diffraction intensities of small single crystals with a volume of less than 1.0 mm
down to 0.1 mm. We have recently upgraded some SENJU components, such as sample environment devices, the detector system, and data processing software. These upgrades of SENJU enhance the possibility and accessibility of SENJU. In this presentation, we will introduce the recent upgrades of SENJU.
Gong, W.; Harjo, S.; 川崎 卓郎; 相澤 一也; 辻 伸泰*
no journal, ,
Magnesium (Mg) and its alloys, as the lightest structural metallic materials, have potential for application under various environments. Here, in-situ neutron diffraction experiments were conducted for investigating the deformation mechanisms at cryogenic temperature in an AZ31 Mg alloy. A commercial extruded AZ31 alloy was used, while the loading direction was parallel to the extrusion direction. In-situ neutron diffraction experiments during tensile and compressive deformation at 21K and 298K tests were performed using a time-of-flight engineering diffractometer -TAKUMI at Japan Proton Accelerator Research Complex (J-PARC). The yield stress increased significantly with decreasing deformation temperature in tensile deformation, but increased slight in compressive deformation. Interestingly, the fracture strain and stress at 21 K increased simultaneously compared to that at 298 K in compressive deformation. The lattice strain and the volume fraction of extension twins were calculated by the variation of diffraction profile. The deformation mechanisms including basal slip, extension twinning, and contraction twinning were quantitatively evaluated by lattice strain and texture results. The different sensitivities of various deformation modes to temperature are responsible for the variation of macroscopic deformation behavior with temperature in AZ31 alloy.
川北 至信; 松浦 直人*; 富永 大輝*; 山田 武*; 玉造 博夢; 中川 洋; 大内 啓一*
no journal, ,
DNA is a TOF type Si crystal analyzer backscattering spectrometer installed at the Japan Proton Accelerator Research Complex (J-PARC) spallation source. DNA uses a pulse-shaping chopper to extract sharp pulsed neutron from strong but broad spectrum of coupled moderator, which achieves good energy resolution (~2.4 micro-eV) and large neutron flux simultaneously. In addition, time-of-flight technique allows us to go high energy transfers of about 1500 micro-eV. Furthermore, the signal-to-noise ratio at DNA achieves 10
, which enables to covers a variety of research fields from biomaterials with small scattering amplitudes or with small quantities of samples (of the order of milligrams). DNA has Si111 analyzers, which allows to access momentum transfer range from 0.08 to 1.86 
. Currently, we are installing Si311 analyzers covering momentum transfer from 1.79 to 3.39 , which overlaps Q-region of Si111. We are developing various sample environments, such as magnet, automatic sample changers, furnace, humidity controller, and radial collimators. We are also promoting the Internet of Things (IoT) of the equipment due to strong demands of remote experiments from COVID-19. We will show the current status and upgrade plan of DNA.
篠原 武尚; 甲斐 哲也; 及川 健一; Su, Y. H.; 土川 雄介; 林田 洋寿*; Parker, J. D.*; 松本 吉弘*; 鬼柳 善明*
no journal, ,
The energy-resolved neutron imaging system, RADEN, in J-RARC was constructed to provide the most suitable environment to perform energy-resolved neutron imaging experiments, which utilize energy-dependent neutron transmission analysis to extract physical quantities and visualize their spatial distributions by using the short-pulsed neutrons' features. Then by using RADEN instrument, it is possible to conduct these imaging experiments with good efficiency and precision, together with the conventional neutron radiography and tomography. In this presentation, we will describe the current status of RADEN and our on-going technical development. In addition, we will present results of application studies of pulsed neutron imaging conducted at RADEN.
Harjo, S.; 相澤 一也; Gong, W.; 山崎 倫昭*; 川崎 卓郎
no journal, ,
The elongation of an LPSO type Mg alloy consisting 25 vol% of LPSO phase was found to increase without sacrificing the tensile strength, when the extrusion ratio or the equivalent strain of the hot-extrusion became higher. This phenomenon is very interesting, considering that the improvements of elongation and of tensile strength due thermo-mechanical processes are usually contradictory properties. In this study, monitoring deformation behavior of the Mg and LPSO phases in hot-extruded LPSO type Mg alloys consisting 25 vol% of LPSO phase by in situ neutron diffraction was carried out to elucidate the reason of the improvement of both elongation and strength by hot-extrusion with high extrusion ratio.