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Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：6 Percentile：84.97(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Ono, Koki*; Higomoto, Toshiya*; Saito, Yugo*; Uchino, Shun; Nishida, Yusuke*; Takahashi, Yoshiro*
Nature Communications (Internet), 12, p.6724_1 - 6724_8, 2021/11
Times Cited Count：8 Percentile：69.3(Multidisciplinary Sciences)Quantum transport is ubiquitous in physics. So far, quantum transport between terminals has been extensively studied in solid state systems from the fundamental point of views such as the quantized conductance to the applications to quantum devices. Recent works have demonstrated a cold-atom analog of a mesoscopic conductor by engineering a narrow conducting channel with optical potentials, which opens the door for a wealth of research of atomtronics emulating mesoscopic electronic devices and beyond. Here we realize an alternative scheme of the quantum transport experiment with ytterbium atoms in a two-orbital optical lattice system. Our system consists of a multi-component Fermi gas and a localized impurity, where the current can be created in the spin space by introducing the spin-dependent interaction with the impurity. We demonstrate a rich variety of localized-impurity-induced quantum transports, which paves the way for atomtronics exploiting spin degrees of freedom.
Okabe, Kota; Yamamoto, Kazami; Kamiya, Junichiro; Takayanagi, Tomohiro; Yamamoto, Masanobu; Yoshimoto, Masahiro; Takeda, Osamu*; Horino, Koki*; Ueno, Tomoaki*; Yanagibashi, Toru*; et al.
Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.853 - 857, 2017/12
The most important issue is to reduce the uncontrolled beam loss in the high intensity hadron accelerator such as J-PARC proton accelerators. The J-PARC 3 GeV Synchrotron (RCS) has a collimator system which narrows a high intensity beam in the RCS. After startup of RCS in 2007, the collimator system of the RCS worked well. However, in April 2016, vacuum leakage at the collimator system occurred during the maintenance operation. To investigate a cause of the failure, we took apart iron shields of the collimator reducing exposed dose of operators. As a result of inspection, we succeeded to identify the cause of the vacuum leakage failure. In this presentation, we report the failure investigation of the beam collimator system in the RCS.
Komori, Yukiko*; Yokokita, Takuya*; Kasamatsu, Yoshitaka*; Haba, Hiromitsu*; Toyoshima, Atsushi; Toyomura, Keigo*; Nakamura, Kohei*; Kanaya, Jumpei*; Huang, M.*; Kudo, Yuki*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1385 - 1388, 2015/02
Times Cited Count：2 Percentile：17.57(Chemistry, Analytical)We studied solid-liquid extraction behavior of carrier-free Mo and W radiotracers onto an Aliquat 336-loaded resin from HCl solutions toward extraction chromatography experiments of element 106, seaborgium(Sg). Distribution coefficients (
) of Mo and W on the resin were determined as a function of HCl concentration by a batch method. On-line extraction chromatography of Mo and W was also carried out in 2-8 M HCl solutions with an automated rapid chemistry apparatus. The order of extraction probability from 2 to 8 M HCl was Mo
W, which reflected the order of the values in the batch experiment.
Ito, Takayoshi; Harjo, S.; Osamura, Kozo*; Hemmi, Tsutomu; Awaji, Satoshi*; Machiya, Shutaro*; Oguro, Hidetoshi*; Nishijima, Gen*; Takahashi, Koki*; Matsui, Kunihiro; et al.
Materials Science Forum, 681, p.209 - 214, 2011/05
Times Cited Count：1 Percentile：52.78(Materials Science, Multidisciplinary)Harjo, S.; Aizawa, Kazuya; Ito, Takayoshi*; Abe, Jun; Osamura, Kozo*; Hemmi, Tsutomu; Jin, X.*; Nakamoto, Tatsushi*; Awaji, Satoshi*; Takahashi, Koki*
no journal, ,
Yokokita, Takuya*; Komori, Yukiko*; Kikutani, Yuki*; Kino, Aiko*; Shiohara, Naoya*; Kasamatsu, Yoshitaka*; Yoshimura, Takashi*; Takahashi, Naruto*; Oe, Kazuhiro; Shinohara, Atsushi*
no journal, ,
We are planning to study a redox behavior of element 106, seaborgium (Sg) based on the comparison of the behaviors with those of molybdenum (Mo) and tungsten (W). In this work, we studied solvent extraction behaviors of Mo(VI), Mo(V), W(VI), and W(V) with Aliquat 336 from hydrochloric acid (HCl). Mo(V) is extracted with higher distribution ratios than those of Mo(VI) in 4 to 11 M HCl. Distribution ratios of Mo(V) obtained by reducing Mo(VI) electrochemically are in good agreement with those of [MoCl
].
Abe, Hironobu; Ikeda, Koki; Mikake, Shinichiro; Nagasaki, Yasushi; Niizato, Tadafumi; Asazuma, Shinichiro; Aoki, Isao; Ishikawa, Nobuyuki; Ishikawa, Hiroyasu; Ishizaki, Nobuhiro; et al.
no journal, ,
no abstracts in English
Toda, Kosuke*; Ueno, Shingo*; Takahashi, Naruto*; Kasamatsu, Yoshitaka*; Yokokita, Takuya*; Oe, Kazuhiro; Yokoyama, Akihiko*
no journal, ,
In order to study the effect of the degree of deformation on the fusion reaction, we have researched for the fusion reaction of 
Lu + 
O and 
Ho + 
Ne. In the systems, the projectile nucleus O is spherical, while Ne is deformed. Thus they are fusion reactions of deformed-spherical nuclei and deformed-deformed nuclei, respectively. Besides, latter system has the same compound nucleus, 
Ir, as the 
Tm + O reaction in previous work. The evaporation residue cross sections were measured by using a stack technique and a gas-jet technique for the projectile energies of 50 to 155 MeV. The cross sections were compared with the theoretical values calculated by HIVAP code. The measured excitation functions were found to agree fairly well with theoretical values. The results are consistent with the idea that the degree of deformation makes an effect on the rising edge of excitation functions near the Coulomb barrier.
Yokokita, Takuya*; Oe, Kazuhiro; Komori, Yukiko*; Kikutani, Yuki*; Kino, Aiko*; Nakamura, Kohei*; Kasamatsu, Yoshitaka*; Takahashi, Naruto*; Yoshimura, Takashi*; Takamiya, Koichi*; et al.
no journal, ,
We carried out solvent extraction of Mo(VI), Mo(V), W(VI) and W(V) in 0.01-0.36 M Aliquat 336 / 0.1-11 M HCl system as model experiments for element 106, seaborgium (Sg). The HCl solutions of Mo(VI), Mo(V), W(VI) and W(V) were prepared using macro amounts of Mo and W. Extraction behaviors of mononuclear Mo and W were also investigated using carrier-free radiotracers 
Mo and 
W, which were produced as 
U(n, f) and Ta (p, n) reaction, respectively. The distribution ratios (D) of Mo(V) and W(V) were higher than those of Mo(VI) and W(VI), respectively. These results suggest that reduction behavior of the group-6 elements can be observed by solvent extraction. The D values of carrier-free Mo(VI) and W(VI) are almost the same as those with macro amounts in 6-11 M HCl. This condition would be suitable for the Sg experiments.
