Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Su, Y. H.; Lau, W. S.*; 篠原 武尚; Parker, J. D.*; 及川 健一; 甲斐 哲也; 土川 雄介; 林田 洋寿*; 松本 吉弘*; Gao, S.*; et al.
no journal, ,
Crystallite size is a crucial parameter in characterising the structural properties of materials, and accurate measurement techniques are essential for various applications in engineering materials science. The neutron Bragg edge imaging method offers a non-destructive and penetrating approach to measure crystallite size of each crystalline phase within a bulk material. Electron Backscatter Diffraction (EBSD) is a popular technique for determining grain sizes and orientations in crystalline materials. This experiment aimed to demonstrate the effectiveness of neutron Bragg edge imaging as a complementary technique to EBSD for grain size characterisation in crystalline materials. We conducted experiments using standard samples with known grain sizes from the EBSD measurements. Two materials were used in the study: pure iron with a ferrite phase and an Fe-24Ni-0.3C alloy with an austenite phase. The time-of-flight neutron transmission imaging experiment was performed at BL22 RADEN in J-PARC MLF. By analysing the obtained Bragg-edge spectra, we were able to obtain information regarding the crystallite size and texture of the samples. To validate the results, a comparison was made using data from both EBSD observations and neutron diffraction measurements from BL19 TAKUMI in J-PARC MLF.
及川 健一; 松本 吉弘*; 佐藤 博隆*; 渡辺 賢一*; Parker, J. D.*; 篠原 武尚; 鬼柳 善明*
no journal, ,
Our Japanese sword research team is attempting to gain insight into the secrets of sword-making techniques by conducting systematic nondestructive study from the viewpoint of crystallographic structure, mainly using the energy-resolved neutron imaging system, RADEN at MLF J-PARC. In particular, the manufacturing process of old swords "Koto" up to the end of the 16th century is not well understood because there are few written records of the sword making process, and it would be an important clue to clarify how the crystallographic structure differs compared to new swords, new-new swords, or modern swords. With the cooperation of NITROPLUS Co., Ltd., we have started the neutron imaging experiment of swords of known provenance from 2021. So far, they have provided us with a total of nine exhibition-class swords in the broad sense of the word. In this presentation, we will report on the analysis results of Bragg-edge imaging and neutron tomography of these swords, Naginata and spear, which are sword-related weapons closely related to the Japanese sword but made in different ways.
長谷美 宏幸; 土川 雄介; 甲斐 哲也; 原田 正英; 及川 健一; 篠原 武尚
no journal, ,
The densities and temperatures of nuclides in a sample are estimated by analyzing the resonance dips in the neutron transmission spectrum. The observed transmission dips are represented as the convolution of the theoretical resonance dip and the temporal distribution of neutrons emitted from the moderator (i.e., the pulse function). The pulse shapes need to be given around arbitrary energies of resonance dips to perform the neutron resonance transmission analysis (NRTA) and the neutron resonance transmission imaging (NRTI). Therefore, we have found that the Cole-Windsor function well reproduces the pulse function of the BL10 NOBORU at MLF and applied it to the resonance analysis code REFIT, resulting in successfully analyzing the resonance dips in the neutron transmission spectrum measure in NOBORU [1]. However, we were concerned that the modification of REFIT, initially developed for cross section measurements, for NRTA/NRTI analysis might cause serious difficulties in future development due to the difference in purposes. Therefore, we have developed the Resonance Analysis code for neutron IMaging "RAIM".
徐 平光; Wang, Y. W.*; Su, Y. H.; 岩本 ちひろ*; Wang, H. H.*; 浜 孝之*; 柴山 由樹; 土川 雄介; Parker, J. D.*; 甲斐 哲也; et al.
no journal, ,
For achieving the carbon neutralization through reducing the greenhouse gas emission, the liquefied natural gas (LNG) has been widely employed as the fuel for electric power plants. As economical cryogenic steel for LNG transport and storage, high-Mn steels have been paid much attention for a high possibility to replace expensive high-Ni martensite steels and high Ni-Cr austenite steels. Its superior cryogenic toughness is thought mostly due to the high thermal stability of austenite even at the LNG storage temperature and the evident mechanical twining effect during the cryogenic deformation. Since four-point bending deformation may induce elastoplastic strain and texture gradient distribution valuable to investigate the twinning effect, it is highly expected to carry out the in-situ/ex-situ cryogenic bending deformation experiment for clarifying the shear-induced twinning mechanism. As a preliminary research, cold-bent samples of high-Mn austenite thick steel plates at room temperature were employed to evaluate the twinning-induced shear band microstructure and confirm the 2D mapping of texture gradient distribution using time-of-flight (TOF) Bragg-edge transmission imaging. Comparably, the quantitative change in triaxial strains and crystallographic texture characteristics at five different regions along the bend radius was evaluated for reference using the angle-dispersive neutron diffraction. The conventional electron backscattering diffraction (EBSD) was employed to provide the direct morphologic information of gradient microstructure of cold-bent high-Mn steel plates. The RADEN neutron transmission profiles obtained from the inner surface layer to the 1/2 thickness layer of cold bent sample show an very interesting preferred orientation charactersitics, quite similar with the density distributions of corresponding orienations of complete pole figures obtained from RESA.
Hu, F. F.*; Qin, T. Y.*; Su, Y. H.; Ao, N.*; Zhou, L.*; 徐 平光; Parker, J. D.*; 篠原 武尚; Wu, S. C.*
no journal, ,
High-frequency induction hardened S38C axles are widely applied in Japan Shinkansen and China bulletin trains. Due to well-designed surface treatment, these axles produce a large gradient change in the material structure from the axle surface to the core, resulting in a large-layer depth of residual strain and microhardness. It is well known that the residual strain of a real component is of great importance for its long-cycle service assessment, mainly at the reduced non-destructive detect interval and low maintenance cost. Fortunately, the neutron beam has a high penetrating capacity, which provides the advantage of using Bragg-edge transmission imaging to characterize the residual strain and microstructure inside large engineering components. In our study, ring shaped specimens of the axle were prepared. The neutron transmission imaging experiments were conducted at RADEN in J-PARC MLF under proposal Nos. 2022A0298 and 2023A0069. The obtained results reveal that the 0-5 mm area of the axle surface is compressive residual strain, while the core region is the combination of the tensile residual strain and the compressive residual strain. In the presentation, we will also analyze and compare the changes in residual strain and microstructure in defective S38C axles at various fatigue stages. We are expecting to employ pulsed neutron imaging data to assess the fatigue resistance of the axle.
栗田 圭輔; 飯倉 寛; 原山 勲; 土川 雄介; 甲斐 哲也; 篠原 武尚; 大平 直也*; 伊藤 大介*; 齊藤 泰司*; 松林 政仁
no journal, ,
原子力科学研究所の敷地内には2つの大型中性子実験施設が設置されている。一つはJ-PARC、もう1つはJRR-3である。それぞれに中性子イメージング装置がある。本講演では、JRR-3の中性子線撮影装置の性能、更新装置、利用実績、撮影例などを紹介する。
土川 雄介; 甲斐 哲也; 佐藤 節夫*; 及川 健一; 篠原 武尚
no journal, ,
中性子共鳴イメージングとは、中性子共鳴ピーク分析により、試料中に存在する元素の定量的評価だけでなく、分布を測定することができる可視化技術である。一般に、中性子イメージングは比較的軽元素の可視化に有効であると考えられている。しかし、軽元素の中性子共鳴の多くはkeV以上のエネルギーを持つため、元素の同定は容易ではない。大強度陽子加速器施設(J-PARC)の物質・生命科学実験施設(MLF)は、核破砕を起こす陽子ビームのバンチ幅が100ns程度と短いため、高エネルギー領域の測定に適しており、高速応答シンチレータ検出器を用いた軽元素同定のための検出器開発が進められている。MLFで稼働している2012年モデルの6-リチウム時間分析中性子検出器(LiTA12)は、50mm四方の感応面積を持ち、空間分解能は約700
mである。この検出器は7Mcpsの計数率を持ち、高速な時間応答により共鳴エネルギー領域の中性子測定に使用されている。最近、LiTA12を使った自動測定やシーケンシャル測定が可能になった。LiTA12は現在、NIDやnGEMのような他の検出器と同じくらい使いやすくなってきた。現在、LiTAを使ってkeV以上の共鳴ピークを持つイメージングを可能とするように更新している。我々は、リチウムや一般的に使用される鉄のような数十から数百keVにピークを持つ元素の定量的イメージングを目指しており、そのためにガンマ線バックグラウンドの解明やプラスチックシンチレータを用いた検出器の高速応答のテストに取り組んでいる。本講演では、LiTA12の最近の開発と、この検出器を用いた測定例を紹介する。
不破 康裕; 岩下 芳久*
no journal, ,
中性子の磁気モーメントは磁場の勾配との相互作用により力を受け、磁場勾配がレンズ軸からの距離に比例する6極磁石は中性子ビームのレンズとして機能する。6極磁場の大きさが固定されている場合にはレンズの焦点距離は中性子の波長とともに変化するが、パルス中性子のTOFに同期して磁場の強さを変調することにより、中性子ビームの焦点距離を広い波長範囲で一定に制御することができる。本研究では磁場変調機能を有する中性子レンズを開発し、拡大光学系を用いたイメージングの実現を目指している。HUNS(北海道大学中性子源)で行われた予備実験では、9から13Aの波長範囲の中性子に対して4倍の拡大倍率でのイメージングが実証した。拡大倍率とカバーする波長範囲は、磁石の変調強度とレンズユニットの数を変えることで調整可能である。この光学系を拡張することで、顕微鏡として機能する波長依存イメージングが可能になる。