Comparative evaluation of two analytical functions for the microdosimetry of ions from H to U

Parisi, A.*; Furutani, K. M.*; 佐藤 達彦; Beltran, C. J.*

Quantum Beam Science (Internet), 8(3), p.18_1 - 18_16, 2024/09

https://doi.org/10.3390/qubs8030018

The analytical microdosimetric function (AMF) implemented in the Monte Carlo code PHITS is a unique tool that bridges the gap between macro- and microscopic scales of radiation interactions, enabling accurate microdosimetric calculations over macroscopic bodies. This study compares the older and newer AMFs in computing microdosimetric probability distributions, mean values, and the relative biological effectiveness (RBE). The newer AMF was found to offer superior performance, particularly for very heavy ions, producing results that align more closely with published in vitro clonogenic survival experiments. These findings suggest that the updated AMF provides a more reliable tool for microdosimetric calculations and RBE modeling, essential for ion radiation therapy and space radiation protection.

A Focusing supermirror for time-of-flight grazing-incidence small-angle neutron scattering measurement

山崎 大; 丸山 龍治; 青木 裕之; 花島 隆泰*; 阿久津 和宏*; 宮田 登*; 曽山 和彦

Quantum Beam Science (Internet), 9(2), p.20_1 - 20_12, 2024/06

https://doi.org/10.3390/qubs9020020

This study developed a neutron-beam focusing supermirror for grazing-incidence small-angle neutron scattering (GISANS) measurements. It was fabricated by depositing NiC/Ti supermirror film with ion-beam sputtering on a precise elliptic surface of fused quartz figured using the elastic emission machining technique. Neutron measurements at a pulsed neutron reflectometer BL17 of MLF, J-PARC successfully demonstrated that the focusing supermirror enhances a beam intensity twentyfold compared with an optimally collimated beam, achieving the signal-to-background ratio of the focal spot as high as 500. The mirror can be readily installed and used at BL17.

Principal preferred orientation evaluation of steel materials using time-of-flight neutron diffraction

徐 平光; Zhang, S.-Y.*; Harjo, S.; Vogel, S. C.*; 友田 陽*

Quantum Beam Science (Internet), 8(1), p.7_1 - 7_13, 2024/01

https://doi.org/10.3390/qubs8010007

Comprehensive information about the microstructure and crystal structure evolution during the preparation/production processes of various materials is in great demand in order to precisely control the microstructure morphology and the preferred orientation characteristics for the excellent strength-ductility-toughness balance of advanced engineering materials. isothermal annealing experiments of cold rolled 17Ni-0.2C (mass %) martensitic steel sheets were carried out by using the TAKUMI and ENGIN-X time-of-flight neutron diffractometers, respectively. The inverse pole figures based on full-profile refinement were extracted to roughly evaluate the preferred orientation features along three principal sample directions of investigated steel sheets using the General Structure Analysis System (GSAS) software with built-in generalized spherical harmonic functions. The consistent rolling direction (RD) inverse pole figures from TAKUMI and ENGIN-X have confirmed that the time-of-flight neutron diffraction has high repeatability and statistical reliability, revealing that the principal preferred orientation evaluation of steel materials is available through 90 TD ND (transverse direction normal direction) rotation of the investigated specimen on the sample stage during two neutron diffraction experiments. Moreover, these RD, TD and ND inverse pole figures before and after in situ experiments were compared with the corresponding inverse pole figures recalculated respectively from the MUSASI-L complete pole figure measurement and the HIPPO in situ microstructure evaluation. The similar orientation distribution characteristics suggested that the principal preferred orientation evaluation method can be applied to in situ microstructure evolution of bulk orthorhombic materials and spatially resolved principal preferred orientation mappings of large engineering structure parts.

Measurement of mechanical behavior of B-enriched MgB wire using a pulsed neutron source

町屋 修太郎*; 長村 光造*; 菱沼 良光*; 谷口 博康*; Harjo, S.; 川崎 卓郎

Quantum Beam Science (Internet), 7(4), p.34_1 - 34_17, 2023/10

https://doi.org/10.3390/qubs7040034

Measuring the actual strain on the MgB filaments are of paramount importance, since tensile stress and strain diminish the critical current. In this study, the strain measurement using neutron diffraction during tensile loading was established. We fabricated a MgB wire enriched with boron-11, an isotope having a smaller neutron absorption cross- section than natural boron, and succeeded in obtaining changes in the lattice constant under tensile loading through Rietveld analysis.

Relationship between internal stress distribution and microstructure in a suspension-sprayed thermal barrier coating with a columnar structure

山崎 泰広*; 篠宮 啓介*; 奥村 忠晴*; 鈴木 賢治*; 菖蒲 敬久; 中村 唯我*

Quantum Beam Science (Internet), 7(2), p.14_1 - 14_12, 2023/05

https://doi.org/10.3390/qubs7020014

The suspension plasma spray (SPS) technique has attracted attention because of its various microstructures, which can be achieved by mixing submicron spray particles with a solvent to form a suspension. Thermal barrier coatings (TBCs) with a columnar structure, which might achieve high strain tolerance, can be obtained using the SPS technique. In this study, the internal stress distribution of the SPS-TBC with different columnar structures was evaluated by hybrid measurement using high-energy synchrotron X-ray diffraction analysis and laboratory low-energy X-rays. The effect of microstructure on the internal stress distribution of the SPS-TBC was discussed on the basis of the experimental results. In addition, the in-plane internal stress was decreased by decreasing the column diameter. The thin columnar microstructure of the SPS-TBC has superior strain tolerance. The internal stresses in the column of the SPS-TBC are periodic decrements caused by stress relaxation in porous layers.

Neutron stress measurement of W/Ti composite in cryogenic temperatures using time-of-flight method

西田 真之*; Harjo, S.; 川崎 卓郎; 山下 享介*; Gong, W.

Quantum Beam Science (Internet), 7(1), p.8_1 - 8_15, 2023/03

https://doi.org/10.3390/qubs7010008

In this study, the thermal stress alterations generated in a tungsten fiber reinforced titanium composite (W/Ti composite) were evaluated by the neutron stress measurement method at cryogenic temperatures. The W/Ti composite thermal loads were repeated from room temperature to the cryogenic temperature (10 K), and alterations in thermal residual stress were evaluated using the neutron in situ stress measurement method. In this measurement, the stress alterations in the titanium matrix and the tungsten fibers were measured. This measurement was carried out by TAKUMI (MLF-BL19) of J-PARC, a neutron research facility in the Japan Atomic Agency. The measurement method of TAKUMI is the time-of-flight (TOF) method. Owing to this measurement method, the measurement time was significantly shortened compared to the angle-dispersion type measurement by a diffractometer. As a result of the measurement, large compressive stresses of about 1 GPa were generated in the tungsten fibers, and tensile stresses of about 100 MPa existed in the titanium matrix. The thermal stresses due to the temperature change between room temperature and cryogenic temperature is caused by the difference of thermal expansions between the tungsten fibers and the titanium matrix, and these stress values can be approximated by a simple elastic theory equation.

Nanopore formation in CeO single crystal by ion irradiation; A Molecular dynamics study

篠嶋 妥*; 神長 龍一*; 石川 法人; 岩瀬 彰宏*

Quantum Beam Science (Internet), 5(4), p.32_1 - 32_14, 2021/11

https://doi.org/10.3390/qubs5040032

分子動力学法に基づく計算手法により、高速重イオンを照射したCeO単結晶において、ナノスケールの穿孔が形成される様子をシミュレーションした。蛍石型結晶構造の中央位置のナノスケールの柱状領域に高い熱エネルギーを投入し、その後の結晶構造の変化を追った結果、照射後0.3ピコ秒に突然ナノ穿孔が発生し、0.5ピコ秒で最大の大きさになるまで成長した。その後は1.0ピコ秒にかけて収縮現象が見られた。阻止能(イオン照射によって投入されたエネルギー密度)の増加とともに、ナノ穿孔の大きさが増加する傾向が見られた。本結果は、ナノ穿孔を作成し、かつ大きさを制御する際の有用な知見を与える。

Multiple wavelengths texture measurement using angle dispersive neutron diffraction at WOMBAT

徐 平光; Liss, K.-D.*

Quantum Beam Science (Internet), 5(2), p.11_1 - 11_14, 2021/06

AA2020-0801.pdf:11.28MB

https://doi.org/10.3390/qubs5020011

In contrast to conventional angle dispersive neutron diffractometers with a single-tube detector or a small-size linear position-sensitive detector, the WOMBAT diffractometer at Australian Nuclear Science and Technology Organisation (ANSTO) is equipped with a large-area curved position-sensitive detector, spanning 120 for the scattering angle 2 and 15 for the azimuth , respectively. Here, WOMBAT was employed to establish a texture measurement environment for complex textured samples, through measuring neutron diffractograms at two selected wavelengths on a typical reference sample of martensite-austenite multilayered steel sheet. All neutron patterns were simultaneously Rietveld analyzed using the software, Materials Analysis Using Diffraction (MAUD). The shorter wavelength enabled to collect the martensite diffraction peaks 110, 200, 211, 220, 310, 222 as well as the austenite diffraction peaks 111, 200, 220, 311, 222, 331 diffraction peaks simultaneously by pre-setting the detector range to 2 = 30150. The longer wavelength enabled to separate the overlapping strong martensite peak 110 and austenite peak 111 more reliably. Moreover, the detector panel division along the vertical direction covers a good stereographic coverage in the azimuthal angle. Such combination of multiple wavelength neutron diffraction combined with simultaneous Rietveld texture analysis was confirmed much valuable to realize high precision measurements for complex textured samples at an orientation distribution function (ODF) graticule of 5, and in a much shorter beam time than the conventional angle dispersive method.

Comprehensive understanding of hillocks and ion tracks in ceramics irradiated with swift heavy ions

石川 法人; 田口 富嗣*; 小河 浩晃

Quantum Beam Science (Internet), 4(4), p.43_1 - 43_14, 2020/12

https://doi.org/10.3390/qubs4040043

LiNbO, ZrSiO, GdGaO, SrTiOについて、200MeV Auイオンを照射し、透過型電子顕微鏡で、照射損傷組織(イオントラックとヒロック)を詳細に観察した。その結果、LiNbO, ZrSiO, GdGaOは、イオントラックとヒロックともにアモルファス化していることが確認され、耐照射性の低い「アモルファス化可能材料」に分類されることが確認された。一方で、CaFなどのフッ化物は、耐照射性の高い「非アモルファス化可能材料」に分類されることが、我々の前回の研究で判明している。ところが、本研究で調べたSrTiOは、2つの分類の中間に当たることが判明した。耐照射性の観点から区別される2つの材料分類を分ける材料基準が何なのか従来から問題となっていたが、本研究により、イオン結合性の強さ、結晶対称性の高さが、その材料基準となることが示唆された。

Double-exposure method with synchrotron white X-ray for stress evaluation of coarse-grain materials

鈴木 賢治*; 城 鮎美*; 豊川 秀訓*; 佐治 超爾*; 菖蒲 敬久

Quantum Beam Science (Internet), 4(3), p.25_1 - 25_14, 2020/09

AA2020-0793.pdf:2.2MB

https://doi.org/10.3390/qubs4030025

粗大粒で構成される材料の2次元回折パターンはリング状とはならずスポット状となるため、従来の回折計と0次元検出器を利用したひずみスキャンニング法では応力評価が困難である。この課題を解決するために2次元検出器を利用した2重露光法を提案した。本研究ではこの技術を白色X線に対して適用するための技術開発を行った。粗大粒で構成される材料に白色X線を照射すると得られる回折はラウエスポットとなる。そこで検出するエネルギーを制限できるCdTeピクセル2次元検出器の開発とそれを利用した応力評価を行った。その結果、オーステナイト系ステンレス鋼を供試材とする曲げ試験片に対して、ほぼ理論値通りのひずみ分布を計測することに成功した。今後、当該技術の向上を図り、実機材料に適用していきたいと考えている。