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Yoshimura, Nobuyuki*; Toyama, Takeshi*; Shobuda, Yoshihiro; Nakamura, Takeshi*; Omi, Kazuhito*; Kobayashi, Aine*; Okada, Masashi*; Sato, Yoichi*; Nakaya, Tsuyoshi*
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.260 - 264, 2023/11
The J-PARC main ring (MR) will be increased to 1.3 MW. To cope with the increase in beam intensity, the intra-bunch feedback system (IBFB) needs to be upgraded to handle higher frequencies up to about 200 MHz. To evaluate the performance and understand the optimal parameters after this upgrade, we are developing a particle tracking simulation that includes the necessary components. The recoherence period induced by chromaticity between tracking simulations and experiments are compared and it cannot be discribed by the simple simulations, and we investigate what mechanisms explain this result. The shift of synchrotron tune caused by longitudinal wakes using tracking simulations are calculated and it find that introducing the effect of longitudinal wakes only does not explain the recoherence period in the experimental results.
Yoshimura, Nobuyuki*; Toyama, Takeshi*; Kobayashi, Aine*; Nakamura, Takeshi*; Okada, Masashi*; Shobuda, Yoshihiro; Nakaya, Tsuyoshi*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.936 - 941, 2023/01
no abstracts in English
Ochi, Kotaro; Funaki, Hironori; Yoshimura, Kazuya; Iimoto, Takeshi*; Matsuda, Norihiro; Sanada, Yukihisa
Radiation and Environmental Biophysics, 61(1), p.147 - 159, 2022/03
Times Cited Count:2 Percentile:47.19(Biology)Katengeza, E. W.*; Sanada, Yukihisa; Yoshimura, Kazuya; Ochi, Kotaro; Iimoto, Takeshi*
Environmental Science; Processes & Impacts, 22(7), p.1566 - 1576, 2020/07
Times Cited Count:9 Percentile:50.05(Chemistry, Analytical)Sakai, Hironori; Hattori, Taisuke; Tokunaga, Yo; Kambe, Shinsaku; Ueda, Hiroaki*; Tanioku, Yasuaki*; Michioka, Chishiro*; Yoshimura, Kazuyoshi*; Takao, Kenta*; Shimoda, Aiko*; et al.
Physical Review B, 98(6), p.064403_1 - 064403_10, 2018/08
Times Cited Count:10 Percentile:45.99(Materials Science, Multidisciplinary)To specify preferential occupation sites of Co substituents and to clarify charge and spin states of Co ions in (La, Co)-cosubstituted hexagonal magnetoplumbite-type (M-type) Sr ferrite, Fe and Co nuclear magnetic resonance (NMR) spectra are measured under zero and external magnetic fields using powdered and single crystalline specimens. To a considerable degree, the charge compensation between La and Co works in the equal (La, Co)-codoped case, where more than half of the Co ions are considered to be present in the minority spin sites at the center of the oxygen tetrahedra, with the = 3/2 state carrying a small orbital moment owing to spin-orbit interaction. The remaining small number of high-spin Co ( = 3/2, = 1) ions with unquenched orbital moments would be distributed to the other octahedral , , and sites.
Shimizu, Takeshi*; Wang, H.*; Tanifuji, Naoki*; Matsumura, Daiju; Yoshimura, Masashi*; Nakanishi, Koji*; Ota, Toshiaki*; Yoshikawa, Hirofumi*
Chemistry Letters, 47(5), p.678 - 681, 2018/05
Times Cited Count:9 Percentile:33.87(Chemistry, Multidisciplinary)Koyama, Takehide*; Ozaki, Yuzuru*; Ueda, Koichi*; Mito, Takeshi*; Kohara, Takao*; Waki, Takeshi*; Tabata, Yoshikazu*; Michioka, Chishiro*; Yoshimura, Kazuyoshi*; Suzuki, Michito; et al.
Journal of the Physical Society of Japan, 81(Suppl.B), p.SB008_1 - SB008_5, 2012/12
Times Cited Count:1 Percentile:10.8(Physics, Multidisciplinary)The normal state properties of a noncentrosymmetric superconductor MoAlC are studied by means of the nuclear magnetic resonance (NMR) experiment. The change of NMR line shape and the peak of the nuclear spin-echo decay rate at 130 K indicate that the MoAlC exhibits the phase transition prior to the emergence of superconductivity. The reduction in the conduction electron density is inferred from the decrease in the nuclear spin-lattice relaxation rate. The nature of the newly found phase transition is discussed by considering the result of the first principle calculations, indicating a good nesting property of the Fermi surfaces.
Koyama, Takehide*; Ozaki, Yuzuru*; Ueda, Koichi*; Mito, Takeshi*; Kohara, Takao*; Waki, Tsuyoshi*; Tabata, Yoshikazu*; Michioka, Chishiro*; Yoshimura, Kazuyoshi*; Suzuki, Michito; et al.
Physical Review B, 84(21), p.212501_1 - 212501_4, 2011/12
Times Cited Count:12 Percentile:44.66(Materials Science, Multidisciplinary)The results of Al nuclear magnetic resonance and specific-heat measurements of the noncentrosymmetric superconductor MoAlC are reported. The phase transition around 130 K is inferred from a distinct change in the NMR spectrum, a clear peak in the spin-echo decay rate, and an anomaly in the specific heat. Possibility of charge-density wave ordering around 130 K is discussed by calculating the Fermi surfaces in the normal states and considering the partial quenching of the Fermi surfaces with the decrease in 1/ below the superconducting transition temperature.
Matsuo, Yoji*; Suzuki, Muneyasu*; Noguchi, Yuji*; Yoshimura, Takeshi*; Fujimura, Norifumi*; Yoshii, Kenji; Ikeda, Naoshi*; Mori, Shigeo*
Japanese Journal of Applied Physics, 47(11), p.8464 - 8467, 2008/11
Times Cited Count:11 Percentile:42.15(Physics, Applied)We have investigated the physical properties of LuFeCuO, which is a derivative material of the electronic ferroelectric LuFeO. From electron diffraction measurements at room temperature, ionic ordering of Fe and Cu in the a-b plane was observed. This ordering is similar to that in LuFeO and has an electric dipole. The observation of small domains (5-10 nm) indicates the presence of polar regions. Dielectric measurements showed that a peak of dielectric constant appeared at around 500 K, and the peak value was about 1000, indicating that LuFeCuO is a dielectric material. We will present the experimental data on the samples prepared under high-pressure oxygen.
Hayakawa, Ryoma*; Nakae, Mari*; Yoshimura, Takeshi*; Ashida, Atsushi*; Fujimura, Norifumi*; Uehara, Tsuyoshi*; Tagawa, Masahito*; Teraoka, Yuden
Journal of Applied Physics, 100(7), p.073710_1 - 073710_8, 2006/10
Times Cited Count:12 Percentile:42.56(Physics, Applied)A structural analysis and dielectric property measurements of silicon nitride films fabricated using atmospheric pressure (AP) plasma were carried out, and the results were compared to a radio frequency (RF) plasma case. Using AP plasma, 1.8-nm-thick films composed of SiNO were obtained in the temperature range from 298 to 773 K. X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry revealed 10% more nitrogen atoms corresponding to the NSi bond in the film using AP plasma than those using RF plasma. In the temperature range, the leakage current densities were not affected by the temperature. Films fabricated at 298 K showed leakage current density of as low as 710A/cm at 5MV/cm. This value was one order of magnitude lower than that using RF plasma.
Fukui, Hironobu*; Hamaguchi, Masafumi*; Yoshimura, Hisao*; Oyamatsu, Hisato*; Matsuoka, Fumitomo*; Noguchi, Tatsuo*; Hirao, Toshio; Abe, Hiroshi; Onoda, Shinobu; Yamakawa, Takeshi; et al.
Proceedings of 2005 Symposia on VLSI Technology and Circuits, p.222 - 223, 2005/00
no abstracts in English
Fukui, Hironobu*; Hamaguchi, Masafumi*; Yoshimura, Hisao*; Oyamatsu, Hisato*; Matsuoka, Fumitomo*; Noguchi, Tatsuo*; Hirao, Toshio; Abe, Hiroshi; Onoda, Shinobu; Yamakawa, Takeshi; et al.
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.169 - 172, 2004/10
no abstracts in English
Hayakawa, Ryoma*; Nakae, Mari*; Yoshida, Shinji*; Tagawa, Masahito*; Teraoka, Yuden; Yoshimura, Takeshi*; Ashida, Atsushi*; Kunugi, Shunsuke*; Uehara, Tsuyoshi*; Fujimura, Norifumi*
no journal, ,
Chemical bonding states of silicon nitride films formed by an atmospheric plasma method and a RF plasma method were analyzed by photoemission spectroscopy with synchrotron radiation and compared each other. The SiN/Si(111) interface formed by the RF plasma method consisted of 5 components. On the other hand, the SiN/Si(111) interface formed by the atmospheric plasma method consisted of 4 components. The SiN component is in the interface formed by the RF plasma method.
Katengeza, E.*; Sanada, Yukihisa; Yoshimura, Kazuya; Ochi, Kotaro; Iimoto, Takeshi*
no journal, ,
The rate of temporal change of radiocesium concentration in bottom sediments is governed not only by its physical decay but also by various ecological processes. In this study, the decreasing trend of radiocesium concentration over wide pond areas of surface sediments (up to 10 cm depth), due to ecological processes, was investigated using plastic scintillation fibers (PSF) and was quantified by the ecological half life. PSF measurements were conducted between 2013 and 2019. Their conversion factors ((Bq/kg)/cps) were obtained by comparison between detected radiation counting rate obtained by PSF and the concentration of radiocesium in sediment cores collected from coinciding positions within the same ponds. A forest catchment pond exhibited the longest ecological half life and may indicate catchment derived radiocesium input as was partly evident in the spatial temporal patterns of radiocesium concentration at this pond's inlet.
Ochi, Kotaro; Yoshimura, Kazuya; Sanada, Yukihisa; Funaki, Hironori; Iimoto, Takeshi*
no journal, ,
The coefficient for converting from the air dose rate to a radiocesium inventory with relaxation mass depth () is proposed by Monte Carlo simulation. We confirm the validity of the conversion coefficient based on vertical distribution of radiocesium in soil and air dose rate obtained by contract research supported by the Nuclear Regulation Authority. The estimated radiocesium inventories based on air dose rate and values ( and ) were defined as CI and CI, respectively. Each CI were compared with integrated radiocesium inventory (MI) in soil samples. Good agreement was observed between CI and MI. This result suggested that the method for estimating radiocesium inventory based on and air dose rate is applicable to environment in Fukushima. By contrast, CI was overestimated compared with MI due to the trend of derived from difference of soil characteristics between Fukushima and Chernobyl.