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Journal Articles

Magnetic diffuse and quasi-elastic scatterings in frustrated magnet YBaCo$$_{4}$$O$$_{7}$$

Soda, Minoru*; Kofu, Maiko; Kawamura, Seiko; Asai, Shinichiro*; Masuda, Takatsugu*; Yoshizawa, Hideki*; Furukawa, Hazuki*

Journal of the Physical Society of Japan, 91(9), p.094707_1 - 094707_5, 2022/09

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Journal Articles

Analyses of $$H$$*(10) dose rates measured in environment contaminated by radioactive caesium; Correction of directional dependence of scintillation detectors

Tsuda, Shuichi; Tanigaki, Minoru*; Yoshida, Tadayoshi; Okumura, Ryo*; Saito, Kimiaki

Radiation Protection Dosimetry, 193(3-4), p.228 - 236, 2021/03

 Times Cited Count:2 Percentile:38.28(Environmental Sciences)

Environmental dose rate monitoring has been performed with various scintillation detectors since the Fukushima Dai-ichi Nuclear Power Plant accident. Gamma-rays from caesium isotopes deposited in soil enter radiation detectors in any direction, but directional dependence of the detectors used for dose rate measurements are not always uniform and the dose rates vary even if measurement takes place at the same place. To investigate the influence of crystal configurations on dose rate, dose rate measurements using several scintillation detectors with different crystal configurations were conducted. By measuring pulse height spectra and multiplying them with spectrum - dose conversion operators (G(E) function), dose rates were deduced and compared. It was found that the dose rates varied within approximately 25% among six detectors. To reduce the differences, the dose rate using G(E) functions determined in rotational geometry were obtained and applied instead. The revised dose rates agreed with one another within uncertainties, but this was not the case of scintillation detector with flat crystal shape, and it means this method could not compensate its strong directional dependence. These experimental results reveal that detectors with superior directional characteristics should be used for environmental dose rate measurement since the compensation of directional dependence using a G(E) function determined in rotational geometry is not always available.

Journal Articles

Emergent spin-1 Haldane gap and ferroelectricity in a frustrated spin-$$frac{1}{2}$$ ladder

Ueda, Hiroshi*; Onoda, Shigeki*; Yamaguchi, Yasuhiro*; Kimura, Tsuyoshi*; Yoshizawa, Daichi*; Morioka, Toshiaki*; Hagiwara, Masayuki*; Hagihara, Masato*; Soda, Minoru*; Masuda, Takatsugu*; et al.

Physical Review B, 101(14), p.140408_1 - 140408_6, 2020/04

 Times Cited Count:3 Percentile:22.2(Materials Science, Multidisciplinary)

Journal Articles

Conceptual study on parasitic low-energy RI beam production with in-flight separator BigRIPS and the first stopping examination for high-energy RI beams in the parasitic gas cell

Sonoda, Tetsu*; Katayama, Ichiro*; Wada, Michiharu*; Iimura, Hideki; Sonnenschein, V.*; Iimura, Shun*; Takamine, Aiko*; Rosenbusch, M.*; Kojima, Takao*; Ahn, D. S.*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(11), p.113D02_1 - 113D02_12, 2019/11


 Times Cited Count:1 Percentile:12.43(Physics, Multidisciplinary)

An in-flight separator, BigRIPS, at RIBF in RIKEN provides each experiment with specific nuclides separated from many nuclides produced by projectile fragmentation or in-flight fission. In this process, nuclides other than separated ones are discarded on the slits in BigRIPS, although they include many nuclides interested from the view point of nuclear structure. In order to extract these nuclides for parasitic experiments, we are developing a method using laser ion-source (PALIS). A test experiment with $$^{78}$$Se beam from RIBF has been performed by using a gas cell set in BigRIPS. Unstable nuclides around $$^{67}$$Se were stopped in the gas cell in accordance with a calculation using LISE code. The stopping efficiency has been estimated to be about 30%. As a next step, we will establish the technique for extracting reaction products from the gas cell.

Journal Articles

Development of compact high field pulsed magnet system for new sample environment equipment at MLF in J-PARC

Watanabe, Masao; Nojiri, Hiroyuki*; Ito, Shinichi*; Kawamura, Seiko; Kihara, Takumi*; Masuda, Takatsugu*; Sahara, Takuro*; Soda, Minoru*; Takahashi, Ryuta

JPS Conference Proceedings (Internet), 25, p.011024_1 - 011024_5, 2019/03

Recently, neutron scattering experiments have been rapidly progressed under high magnetic field. In the J-PARC, proto-type compact pulse magnet system with the power supply, the coil and the sample stick has been developed. Basic specifications of the power supply are as follows; maximum charged voltage with capacitor is 2 kV, maximum current is 8 kA, repetition rate is a pulse per several minutes and pulse duration is several msec. Maximum magnetic field in the coil is more than 30 Tesla. The sample stick is designed for Orange-Cryostat. In this presentation, We report the details of the pulsed magnet system and the performance of it on neutron scattering experiments at MLF beam line (HRC).

Journal Articles

Review of the performance of a car-borne survey system, KURAMA-II, used to measure the dose rate after the Fukushima Dai-ichi Nuclear Power Plant accident

Tsuda, Shuichi; Tanigaki, Minoru*; Yoshida, Tadayoshi; Saito, Kimiaki

Hoshasen, 44(3), p.109 - 118, 2018/11

JAEA has started to perform dose rate monitoring using a car-borne survey system KURAMA to rapidly produce the dose rate mappings of the deposited radionuclides in the environment after the Fukushima Dai-ichi Nuclear Power Plant accident. KURAMA is a car-borne survey system developed by Kyoto University to perform dose rate monitoring in a wide area in detail with rapidity. By improving KURAMA with continuous dose rate monitoring, the 2nd generation of KURAMA (KURAMA-II) succeeded in downsizing, durability and automated transmission of data so that enable detailed dose rate mapping in wide area in shorter period of time. This paper reports the radiation characteristics and the simulation analysis of KURAMA-II on the special issue of Hoshasen, the journal of Ionization Radiation Division in the Japan society of applied physics.

Journal Articles

Dependence of dose rate measurement in the environment on crystal configuration of scintillation detectors

Tsuda, Shuichi; Tanigaki, Minoru*; Yoshida, Tadayoshi; Okumura, Ryo*; Saito, Kimiaki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 17(1), p.11 - 17, 2018/03

Environmental dose rate monitoring has been performed using scintillation detectors since the Fukushima Dai-ichi Nuclear Power Plant accident happened. After the accident, various scintillation detectors with directional dependence are used in the measurement, though detectors with superior directional dependence are needed because photons come from various direction in the environment. To investigate the influence of crystal configurations on indicated values of dose rates, pulse height spectra were measured using scintillation-based detectors with different crystal configurations and ambient dose rates were obtained using a spectrum - dose conversion operator (G(E) function). It is found that the dose rate for a rectangular-parallelepiped crystal is $$sim$$ 40% than that for a cylindrical one at the maximum. However, the values agreed within 10% among all the detectors irrespective of the crystal shapes, using G(E) functions determined in a rotational irradiation geometry.

Journal Articles

Spin model of O$$_{2}$$-based magnet in a nanoporous metal complex

Soda, Minoru*; Homma, Yuki*; Takamizawa, Satoshi*; Kawamura, Seiko; Nakajima, Kenji; Masuda, Takatsugu*

Journal of the Physical Society of Japan, 85(3), p.034717_1 - 034717_9, 2016/03

 Times Cited Count:1 Percentile:11.81(Physics, Multidisciplinary)

Inelastic neutron scattering experiments are performed on the nanoporous metal complex Cu-${{it trans}}$-1,4-cyclohexanedicarboxylic acid (Cu-CHD) adsorbing O$$_{2}$$ molecules to identify the spin model of the O$$_{2}$$-based magnet realized in the host complex. It is found that the magnetic excitations of Cu-CHDs adsorbing low- and high-concentration O$$_{2}$$ molecules are explained by different spin models, the former by spin dimers and the latter by spin trimers. By using the obtained parameters and by assuming that the levels of the group of the highest energy states are reduced because of the nonnegligible spin dependence of the molecular potential of oxygen, the magnetization curves are explained quantitatively.

Journal Articles

The Verification tests of the melting conditions for homogenization of metallic LLW at the JAEA

Nakashio, Nobuyuki; Osugi, Takeshi; Iseda, Hirokatsu; Tohei, Toshio; Sudo, Tomoyuki; Ishikawa, Joji; Mitsuda, Motoyuki; Yokobori, Tomohiko; Kozawa, Kazushige; Momma, Toshiyuki; et al.

Journal of Nuclear Science and Technology, 53(1), p.139 - 145, 2016/01

 Times Cited Count:1 Percentile:11.02(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Science from the initial operation of HRC

Ito, Shinichi*; Yokoo, Tetsuya*; Masuda, Takatsugu*; Yoshizawa, Hideki*; Soda, Minoru*; Ikeda, Yoichi*; Ibuka, Soshi*; Kawana, Daichi*; Sato, Taku*; Nambu, Yusuke*; et al.

JPS Conference Proceedings (Internet), 8, p.034001_1 - 034001_6, 2015/09

Journal Articles

Fabrication of hard-coated optical absorbers with microstructured surfaces using etched ion tracks; Toward broadband ultra-low reflectance

Amemiya, Kuniaki*; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Shitomi, Hiroshi*; Numata, Takayuki*; Kinoshita, Kenichi*; Tanabe, Minoru*; Fukuda, Daiji*

Nuclear Instruments and Methods in Physics Research B, 356-357, p.154 - 159, 2015/08

 Times Cited Count:9 Percentile:61.94(Instruments & Instrumentation)

Broadband low reflectance materials have various applications in the field of optical energy management; however, materials with ultra-low reflectance (below 0.1%) have been considered as mechanically delicate. We have developed a novel hard-surface optical absorber with microstructured, diamond-like carbon coated ion tracks on CR-39 plastic substrate. The spectral reflectance of the first prototype was below 2% for wavelengths ranging from 400 nm to 1400 nm; moreover, the optical absorber had mechanically hard surface and exhibited temporal durability. Choosing the appropriate design of the surface structure and coating layer is likely to reduce the reflectance to the order of 0.1%. This technique yields easy-to-handle broadband ultra-low reflectance absorbers.

Journal Articles

Measurements and evaluations of air dose rates around Fukushima, 4; Practical aspects of air dose rate measurements in the environment

Tsuda, Shuichi; Yoshida, Tadayoshi; Ando, Masaki; Matsuda, Norihiro; Mikami, Satoshi; Tanigaki, Minoru*; Okumura, Ryo*; Takamiya, Koichi*; Sato, Nobuhiro*; Seki, Akiyuki; et al.

Radioisotopes, 64(4), p.275 - 289, 2015/04

This article provides practically useful information on air dose rate measurements in the environments. The basic requirements for the accurate measurements are described giving actual data. The characteristics and some measured results are shown for reliable methods which are widely used in the environmental radiation measurements. Further, information is given on internet sites where air dose rates and related data obtained by official organizations can be browsed.

Journal Articles

Measurement of air dose rates over a wide area around the Fukushima Dai-ichi Nuclear Power Plant through a series of car-borne surveys

Ando, Masaki; Nakahara, Yukio; Tsuda, Shuichi; Yoshida, Tadayoshi; Matsuda, Norihiro; Takahashi, Fumiaki; Mikami, Satoshi; Kinouchi, Nobuyuki; Sato, Tetsuro*; Tanigaki, Minoru*; et al.

Journal of Environmental Radioactivity, 139, p.266 - 280, 2015/01

 Times Cited Count:49 Percentile:83.41(Environmental Sciences)

A series of car-borne surveys using the KURAMA and KURAMA-II systems was conducted in a wide area in eastern Japan from June 2011 to December 2012 to evaluate the distribution of air dose rates around the Fukushima Dai-ichi Nuclear Power Plant, and to determine the time-dependent trend of decrease in air dose rates. An automated data processing system was established, which enables analyses of large amounts of data obtained with the use of about 100 units of the measurement system in a short time. The initial data for studying the migration status of radioactive cesium was obtained in the first survey, followed by the other car-borne surveys having wider measurement ranges. Comparing the measured air dose rates obtained in each survey, it was found that the decreasing trend of air dose rates measured through car-borne surveys was larger than that expected from the physical decay of radioactive cesium and that measured using NaI (Tl) survey meters around the road.

Journal Articles

Spin-nematic interaction in the multiferroic compound Ba$$_{2}$$CoGe$$_{2}$$O$$_{7}$$

Soda, Minoru*; Matsumoto, Masashige*; M$"a$nsson, M.*; Kawamura, Seiko; Nakajima, Kenji; Shiina, Ryosuke*; Masuda, Takatsugu*

Physical Review Letters, 112(12), p.127205_1 - 127205_5, 2014/03

 Times Cited Count:34 Percentile:83.63(Physics, Multidisciplinary)

We demonstrate the existence of the spin-nematic interactions in an easy-plane type antiferromagnet Ba$$_{2}$$CoGe$$_{2}$$O$$_{7}$$ by exploring the magnetic anisotropy and spin dynamics. The combination of neutron scattering and magnetic susceptibility measurements reveals that the origin of the in-plane anisotropy is an antiferro-type interaction of the spin-nematic operator. The relation between the nematic operator and the electric polarization in the ligand symmetry of this compound is presented. The introduction of the spinnematic interaction is useful to understand the physics of spin and electric dipole in multiferroic compounds.

JAEA Reports

Construction of a car-borne survey system for measurement of dose rates in air; KURAMA-II, and its application

Tsuda, Shuichi; Yoshida, Tadayoshi; Nakahara, Yukio; Sato, Tetsuro; Seki, Akiyuki; Matsuda, Norihiro; Ando, Masaki; Takemiya, Hiroshi; Tanigaki, Minoru*; Takamiya, Koichi*; et al.

JAEA-Technology 2013-037, 54 Pages, 2013/10


JAEA has been performing dose rate mapping in air using a car-borne survey system KURAMA-II. The KURAMA system is a GPS-aided mobile radiation monitoring system that has been newly developed by Kyoto University Research Reactor Institute in response to the nuclear disaster. The KURAMA system is composed of an energy-compensated scintillation survey meter for measuring dose rate, electric device for controlling both the dose rates and the position data from a GPS module, a computer server for processing and analyzing data from KURAMA, and client PCs for providing for end users. The KURAMA-II has been improved in small-packaging, durability, and automated data transmission. In consequence, dose rate mapping in wide area has become possible in shorter period of time. This report describes the construction of KURAMA-II, its application and a suggestion of how to manage a large number of KURAMA-II.

Journal Articles

Lower critical fields and the anisotropy in PrFeAsO$$_{1-y}$$ single crystals

Okazaki, Ryuji*; Konczykowski, M.*; Van der Beek, C. J.*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Masaaki*; Shishido, Hiroaki*; Yamashita, Minoru*; Ishikado, Motoyuki; Kito, Hijiri*; et al.

Physica C, 470(Suppl.1), p.S485 - S486, 2010/12

 Times Cited Count:0 Percentile:0(Physics, Applied)

We report the lower critical fields $$H_{c1}$$ measurements on Fe-based oxipnictide PrFeAsO$$_{1-y}$$ single crystals for $$H$$ $$parallel$$ $$c$$ and $$H$$ $$parallel$$ $$ab$$-planes. To avoid the difficulty of $$H_{c1}$$ determinations due to the flux pinning, we developed a novel method using a miniature hall-sensor array which can evaluate the local magnetic induction ai each sensor position. The hall sensor which is placed on the edge of the crystal clearly resolves the first flux penetration from the Meissner state. The temperature dependence of $$H_{c1}$$ for $$H$$ $$parallel$$ $$c$$ is well scaled by the in-plane penetration depth and is consistent with a full-gap superconducting state. The anistropy of $$H_{c1}$$ at low temperatures is estimated to be $$sim$$ 3, which is much smaller than of $$H_{c2}$$. This indicates the multiband superconductivity, in which the active bands for superconductivity are more two-dimensional.

Journal Articles

Disorder and flux pinning in superconducting pnictide single crystals

Van der Beek, C. J.*; Rizza, G.*; Konczykowski, M.*; Fertey, P.*; Monnet, I.*; Okazaki, Ryuji*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Masaaki*; Shishido, Hiroaki*; et al.

Physica C, 470(Suppl.1), p.S385 - S386, 2010/12

 Times Cited Count:1 Percentile:6.58(Physics, Applied)

Crystalline disorder in the pnictide superconductor PrFeAsO$$_{1-x}$$ is studied using magneto-optical visualisation of flux penetration, transmission electron microscopy, and X-ray diffraction using synchrotron radiation. Critical-state like flux distributions and the magnitude and temperature dependence of the critical current demonstrate bulk vortex pinning by oxygen vacancies at all temperatures.

Journal Articles

Development of the volume reduction treatment of solid waste system by ultra-high frequency induction furnace

Sakakibara, Tetsuro; Aoyama, Yoshio; Yamaguchi, Hiromi; Sasaki, Naoto*; Nishikawa, Takeshi*; Murata, Minoru*; Park, J.*; Taniguchi, Shoji*; Fujita, Michiru*; Fukuda, Tomoyuki*; et al.

Proceedings of International Waste Management Symposium 2009 (WM '09) (CD-ROM), 15 Pages, 2009/03

The volume reduction treatment of solid waste system by ultra-high frequency induction furnace (UHFIF) was developed from FY2005 to FY2007. Basic data for melting performance were collected by non-radioactive experiments using the bench scale UHFIF with a crucible capacity of 10 liters. Based on the obtained data, engineering specifications were evaluated for a demonstration scale UHFIF with a crucible capacity of 30 liters. A new demonstration scale UHFIF was constructed and melting experiments of surrogate wastes were carried out by this furnace. It was confirmed that the demonstration scale UHFIF can melt ferrous metal, ceramics and aluminum all together and stabilize aluminum by oxidation to alumina. Density, chemical composition, and surface condition of the solidified substances were analyzed, and homogeneity of the solidified substances was confirmed. Melting behavior in the demonstration scale UHFIF was analyzed by computer simulation and simulation results agreed well with the experimental ones. From the design study for a full scale UHFIF with a crucible capacity of 100 liters, basic specifications were evaluated for the full scale UHFIF. Based on the obtained specification, melting behavior in the full scale UHFIF was analyzed by computer simulation.

Journal Articles

Lower critical fields of superconducting PrFeAsO$$_{1-y}$$ single crystals

Okazaki, Ryuji*; Konczykowski, M.*; Van der Beek, C. J.*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Motoyuki*; Shishido, Hiroaki*; Yamashita, Minoru*; Ishikado, Motoyuki; Kito, Hijiri*; et al.

Physical Review B, 79(6), p.064520_1 - 064520_6, 2009/02

 Times Cited Count:59 Percentile:87.72(Materials Science, Multidisciplinary)

We have studied the lower critical fields H$$_{c1}$$ of superconducting iron oxipnictide PrFeAsO$$_{1-y}$$ single crystals for H parallel and perpendicular to the ab-planes.

JAEA Reports

Examination on small-sized cogeneration HTGR for developing countries

Sakaba, Nariaki; Tachibana, Yukio; Shimakawa, Satoshi; Ohashi, Hirofumi; Sato, Hiroyuki; Yan, X.; Murakami, Tomoyuki; Ohashi, Kazutaka; Nakagawa, Shigeaki; Goto, Minoru; et al.

JAEA-Technology 2008-019, 57 Pages, 2008/03


The small-sized and safe cogeneration High Temperature Gas-cooled Reactor (HTGR) that can be used not only for electric power generation but also for hydrogen production and district heating is considered one of the most promising nuclear reactors for developing countries where sufficient infrastructure such as power grids is not provided. Thus, the small-sized cogeneration HTGR, named High Temperature Reactor 50-Cogeneration (HTR50C), was studied assuming that it should be constructed in developing countries. Specification, equipment configuration, etc. of the HTR50C were determined, and economical evaluation was made. As a result, it was shown that the HTR50C is economically competitive with small-sized light water reactors.

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