Papers by Keyword: Neutron

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Authors: Haider F. Abdul Amir, Abu Hassan Husin, Saafie Salleh, Fuei Pien Chee
Abstract: Neutron bombardment on semiconductor material causes defects, one such primary physical effect is the formation of displacement defects within the crystal lattice structure, and such defects effectively decrease the mean free path and thus shorten the recombination time. Ionizing radiation causes creation of electron-hole pair in the gate oxide and in parasitic insulating layers of the MOS devices. Calculations show increase of the dark current in depletion region caused by a single neutron. Determination of energy and angular distribution of primary knock on atoms, with 14 MeV neutron irradiation in silicon are presented.
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Authors: Tatsumi Hirano, Kishio Hidaka, Daiko Takamatsu, Norikazu Takahashi, Keitaro Shishido, Masato Sasaki, Yuichi Kawashima
Abstract: Internal residual stresses in the pistons of motor vehicle engines were measured to verify the accuracy of residual stresses estimated by thermal simulations. Coarse crystal grains in aluminum casting alloys frequently make it difficult to measure neutron diffraction profiles if a conventional diffractometer is used for steady reactors [1]. Therefore, the Takumi diffractometer installed at the Japan Proton Accelerator Research Complex (J-PARC), which is a pulse neutron source, was applied to measure them. Residual stresses in pistons determined by the method of neutron diffraction were in good agreement with those estimated through thermal simulations. We concluded from these results that the thermal simulations could be applied to designing and producing pistons. Moreover, Young's modulus and Poisson's ratio for aluminum-silicon casting alloy were determined by using neutron diffraction. We also verified that internal residual stresses could be measured with a tensile sample holder by using the Takumi diffractometer.
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Authors: Shunichi Takahashi, Toshihiko Sasaki, Yukio Sato, Kengo Iwafuchi, Hiroshi Suzuki, Yukio Morii, Yasuto Kondo, Ryoichi Monzen, Yukio Hirose
Abstract: As an important industrial problem, the rolling contact fatigue damage is accumulated in rails during the repeated passage of trains over the rails, and rail failures may occur from the cracks grown in the rails. In order to prevent such rail failures, the estimation of the behavior of internal rail cracks is required based on the exact engineering analysis model as well as conducting rail test to search rail defects. The purposes of this paper are to apply the neutron stress measurement to rails, and to obtain residual stress state in the rails for the above purpose. The rail samples used were those that have been used in service line in Japan for about six years (222 million gross tons). The neutron measurement was conducted using the Residual Stress Analyzer (RESA) of the Japan Atomic Energy Agency (JAEA). The present measurement of stresses in rails by the neutron diffraction method was the first attempt in Japan.
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Authors: Toshihiko Sasaki
Abstract: In order to study the method of the neutron stress measurement using the cosα method, a numerical simulation study was performed and the result was compared with author's former experiment. The results of the simulation study agreed with those obtained in the previous experiment, which suggests the validity of the present method for neutron stress measurement.
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Authors: Makoto Hayashi, Shinobu Okido
Abstract: In the X-ray diffraction method, the diffraction intensity, the half-value width, the residual stress and the amount of residual austenitic phase can be measured. By using these parameters, the quality, the mechanical properties and the fatigue strength of materials, the remaining life of fatigue and creep can be evaluated. While the X-ray study has been widely performed for the various kinds of industrial fields in the laboratory, the applications to the actual structure and components have not so many. However, the small size X-ray residual stress analyzer, the position sensitive detector and the micro area diffraction apparatus have been developed for these twenty years. Thus the X-ray diffraction methods have been variously applied to the industrial fields. The X-ray diffraction methods were used to be applied for the large scale structures and machine parts, but recently applied to the semi-conductor fields. On the other hand, the neutron diffraction method has been introduced to measure the residual stresses in the internals of components because of its deep penetration depth. Based on the experiences of X-ray diffraction method, the various kinds of techniques have been proposed. In this paper, the applications of X-ray and neutron diffraction method to the reliability evaluations of structural components and the electronic devices are described.
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Authors: K. Kobayashi, H. Ohyama, K. Hayama, Y. Takami, Eddy Simoen, A. Poyai, Cor Claeys, A. Mohammadzadeh, S. Kohiki
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Authors: Zhi Qiang Shen, Qing Kang, Jun Xu, Zheng Gang Wang, You Jun Zeng
Abstract: Cement-based material samples having 0%, 5%, 10% and 20% B4C concentrations have been prepared for this reserach. Neutron attenuation measurement has been done by using 14.8MeV neutrons from the 5SDH-2 accelerator, and some mechanics properties of the same proportion also have been tested. It has been shown that when the B4C precentage and thickness of the samples increase, neutron attenuation values of the samples increase. Both the flexural and compressive strength firstly increased with B4C addition up to 10% approximately, and then decreased sharply with an addition up to 20%. It is thus possible to enhance the neutron shielding property of cement-based materials by adding B4C.
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Authors: Bharoto, Achmad Ramadhani, Nadi Suparno, Tri Hardi Priyanto
Abstract: National Nuclear Energy Agency of Indonesia has several neutron beam instruments for materials science research. One of the instrument is Four Circle Diffractometer / Texture Diffractometer for study of crystal structure and texture measurement. Due to the instrument is fully occupied by many samples, the instruments has to be further developed in order to conduct experiment effectively and efficiently. For that reason, the instrument controller has been replaced with a new programmable controller that can handle all axis simultaneously. Since the controller has been replaced with the new one, a software for data acquisition and measurement also has been modified using a visual basic of programming language with an addition of function, i.e. an automatic measurement for either single-crystal or poly-crystal sample. The software calculates four peaks of Miller indices of the sample for determining the crystal position to be scanned. Then, the software performs the automatic measurement started from scanning the axis of θ-2θ, calculating the peak position by fitting the data obtained from sample diffraction data, then positioning the θ and 2θ axis to the peak position. Finally, the software performs the scanning of the π-χ axis for texture analysis, and save the experiment data into a certain format for the texture analysis software, i.e. Material Analysis Using Diffraction (MAUD).
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Authors: Hans Heissenstein, Reinhard Helbig
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Authors: Evgenia V. Kalinina, G. Kholuyanov, G. Onushkin, D.V. Davydov, Anatoly M. Strel'chuk, Andrey O. Konstantinov, Anders Hallén, V.A. Skuratov, Andrej Yu. Kuznetsov
Abstract: The influence of the irradiation with neutrons, Kr+ (245 MeV) and Bi+ (710 MeV) ions on the optical and electrical properties of high-resistivity, high-purity 4H-SiC epitaxial layers grown by chemical vapor deposition was investigated using photoluminescence and deep-level transient spectroscopy. Electrical characteristics were studied using Al and Cr Schottky barriers as well as p+-n-n+ diodes fabricated by Al ion implantation on this epitaxial layers. It was found that both "light" neutrons and high energy heavy ions introduced identical defect centers in 4H-SiC. So, even at extremely high density of the ionization energy of 34 keV/nm, typical for Bi+ ion bombardment, damage structure formation in SiC single crystal is governed by energy loss in elastic collisions.
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