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Zhai, Y.*; Luo, P.*; Nagao, Michihiro*; Nakajima, Kenji; Kikuchi, Tatsuya*; Kawakita, Yukinobu; Kienzle, P. A.*; Z, Y.*; Faraone, A.*
Physical Chemistry Chemical Physics, 23(12), p.7220 - 7232, 2021/03
Times Cited Count:3 Percentile:27(Chemistry, Physical)Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.
JAEA-Technology 2011-031, 123 Pages, 2012/01
The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.
Nagao, Tatsuya*; Igarashi, Junichi
Physica B; Condensed Matter, 345(1-4), p.70 - 73, 2004/03
Times Cited Count:1 Percentile:7.12(Physics, Condensed Matter)To investigate the effect of the lattice distortion on the resonant X-ray scattering (RXS) spectra in DyBC, we study the crystal electric field Hamiltonian to fit the low-lying level scheme. By using the quasi-quartet ground states of the Hamiltonian, we analyze the cooperative Jahn-Teller effect at absolute zero. We find that a certain type of buckling of sheets of B and C atoms is an energetically favored state. This naturally leads to a canted quadrupole ordering phase consistent with the experiment. We show that the obtained lattice distortion gives rise to large intensities on RXS spectra around the Dy L edge by modulating 5d bands.
Nagao, Tatsuya*; Igarashi, Junichi
Journal of the Physical Society of Japan, 72(9), p.2381 - 2384, 2003/09
Times Cited Count:10 Percentile:55.03(Physics, Multidisciplinary)We examine the mechanism of the X-ray diffraction process by including the Thomson scattering (TS) term in addition to the resonant X-ray scattering (RXS) term near the Ce L absorption edge in the antiferroquadrupole (AFQ) ordering phase of CeB. Assuming the AFQ order in the 4f states but without any lattice distortion, we obtain the TS intensity comparable to the RXS intensity, owing to the anisotropic charge distribution of 4f states. The present calculation reproduces well the interference pattern between the TS and RXS terms for the (5/2,3/2,3/2) spot observed in the recent experiment. The result suggests that the TS signal as well as the main peak of the RXS signal are a direct reflection of the AFQ order in CeB.
Igarashi, Junichi; Nagao, Tatsuya*
Journal of the Physical Society of Japan, 72(5), p.1279 - 1286, 2003/05
Times Cited Count:13 Percentile:61.11(Physics, Multidisciplinary)We study the resonant X-ray scattering (RXS) spectra at the Dy L_ absorption edge in the quadrupolar ordering phase of DyBC. Analyzing the buckling of sheets of B and C atoms, we construct an effective model that the crystal field is acting on the 5d and 4f states with the principal axes different for different sublattices. Treating the 5d states as a band and the 4f states as localized states, we calculate the spectra within the dipole transition. We take account of processes that (1) the lattice distorion directly modulates the 5d states and (2) the charge anisotropy of the quadrupole ordering 4f states modulates the 5d states through the 5d-4f Coulomb interaction. The former process is found to give dominant contribution to the spectra.
Nagao, Tatsuya*; Igarashi, Junichi
Physica B; Condensed Matter, 329-333(Part2), p.628 - 630, 2003/05
Times Cited Count:5 Percentile:31.44(Physics, Condensed Matter)For elucidating the relation between the resonant X-ray scattering (RXS) signal and the orbital order, we calculate the RXS spectra near the Dy L absorption edge in DyBC, in the antiferro-quadrupole (AFQ) ordering phase. Using a microscopic model that the 4f states of Dy are atomic while the 5d states form an energy band with a reasonable density of states, we obtain sufficient RXS intensities on the AFQ superlattice spot assuming the quadrupole order in the 4f states but without any lattice distortion, in good agreement with the recent experiment. The present result demonstrates the mechanism that the intensity is brought about by the modulation of 5d states through the anisotropic term of the 5d-4f Coulomb interaction.
Igarashi, Junichi; Nagao, Tatsuya*
Journal of the Physical Society of Japan, 71(7), p.1771 - 1779, 2002/07
Times Cited Count:15 Percentile:63.88(Physics, Multidisciplinary)no abstracts in English
Ichikawa, Tatsuya*; Sato, Yoshishige*; Watanabe, Hiroshi*; Nagao, Yuto; Seito, Hajime
no journal, ,
no abstracts in English
Ichikawa, Tatsuya*; Sato, Yoshishige*; Watanabe, Hiroshi*; Seito, Hajime; Nagao, Yuto
no journal, ,
Kofu, Maiko; Kajiwara, Takashi*; Kawamura, Seiko; Kikuchi, Tatsuya*; Nakajima, Kenji; Matsuura, Masato*; Shibata, Kaoru; Nagao, Michihiro*; Yamamuro, Osamu*
no journal, ,
no abstracts in English