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Yamasaki, Atsushi*; Fujiwara, Hidenori*; Tachibana, Shoichi*; Iwasaki, Daisuke*; Higashino, Yuji*; Yoshimi, Chiaki*; Nakagawa, Koya*; Nakatani, Yasuhiro*; Yamagami, Kohei*; Aratani, Hidekazu*; et al.
Physical Review B, 94(11), p.115103_1 - 115103_10, 2016/11
Times Cited Count：18 Percentile：57.36(Materials Science, Multidisciplinary)In this study, we systematically investigate three-dimensional(3D) momentum-resolved electronic structures of Ruddlesden-Popper-type iridium oxides Sr
Ir
O
using soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES). Our results provide direct evidence of an insulator-to-metal transition that occurs upon increasing the dimensionality of the IrO
-plane structure. This transition occurs when the spin-orbit-coupled 
= 1/2 band changes its behavior in the dispersion relation and moves across the Fermi energy. By scanning the photon energy over 350 eV, we reveal the 3D Fermi surface in SrIrO
and 
-dependent oscillations of photoelectron intensity in SrIrO
. To corroborate the physics deduced using low-energy ARPES studies, we propose to utilize SX-ARPES as a powerful complementary technique, as this method surveys more than one whole Brillouin zone and provides a panoramic view of electronic structures.
Nakasone, Shunya*; Yoshii, Taiki*; Shibuya, Kengo*; Yunoki, Akira*; Sakai, Hirotaka*; Shimada, Taro; Manabe, Seiya*; Matsumoto, Tetsuro*
no journal, ,
Cable has become subject to clearance since the revision of the clearance regulations. Ni-63, a nuclide that is difficult to measure, is produced by the activation of copper in cables. When calculating the amount of Ni-63 produced, the activation cross section in the thermal neutron region differs by a factor of about 6 between nuclear data libraries, so that accurate activation calculations have not been possible. Therefore, the purpose of this study is to improve the accuracy of the calculation of Cu activation and to estimate the reaction cross section of Cu-63(n,p)Ni-63 in the thermal neutron region with good accuracy based on actual measurements. In this presentation, the uncertainty of the thermal neutron fluence contributing to the Cu activation was evaluated using Au-198 after neutron irradiation at JRR-3 in JAEA. High-purity gold and copper samples were placed alternately, and the entire sample was packaged in aluminum foil and sealed in an irradiation capsule, which was placed at the bottom of JRR-3 HR-2 with the capsule lid facing upward. Three irradiation capsules were prepared and irradiated with neutrons for 10, 20, and 30 minutes, respectively. About 50 days after irradiation, the radioactivity was measured using a Ge semiconductor detector. The results showed that the radioactivity per unit mass of gold samples irradiated in each irradiation was the highest in the sample placed at the top of the capsule and decreased by 6
8% toward the bottom of the capsule. This trend is reasonable. The average value of the thermal neutron fluence rate for all samples was 7 
10
cm
s
. These results confirm that the thermal neutron fluence can be determined with an accuracy on the order of percent.
Fukai, Megumi*; Nakasone, Shunya*; Yunoki, Akira*; Yamamoto, Kota*; Makino, Yoshiki*; Shimada, Asako; Yoshii, Taiki*; Shibuya, Kengo*; Sakai, Hirotaka*; Shimada, Taro
no journal, ,
no abstracts in English
Nakasone, Shunya*; Fukai, Megumi*; Yunoki, Akira*; Shimada, Asako; Yoshii, Taiki*; Shibuya, Kengo*; Sakai, Hirotaka*; Shimada, Taro
no journal, ,
no abstracts in English
