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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.
Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio; Koseki, Tadashi; Yamamoto, Noboru; Yoshii, Masahito
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1038 - 1040, 2018/06
Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio*; Koseki, Tadashi*; Yamamoto, Noboru*; Hori, Yoichiro*
Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2290 - 2293, 2017/06
The J-PARC is a high intensity proton facility and the accelerator consists of a 400 MeV linac, a 3 GeV Rapid Cycling Synchrotron (RCS) and a 30 GeV Main Ring Synchrotron (MR). We have taken many hardware upgrades such as front end replacement and energy upgrade at the linac, vacuum improvement, collimator upgrade, etc. The beam powers for the neutrino experiment and hadron experiment from the MR have been steadily increased by tuning and reducing beam losses. The designed 1 MW equivalent beam was demonstrated and user program was performed at 500 kW from the RCS to the neutron and muon experiments. We have experienced many failures and troubles, however, to impede full potential and high availability. In this report, operational performance and status of the J-PARC accelerators are presented.
Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Toda, Makoto*; Yoshii, Masahito*; Schnase, A.*
Nuclear Instruments and Methods in Physics Research A, 835, p.119 - 135, 2016/11
Times Cited Count：6 Percentile：49.29(Instruments & Instrumentation)A magnetic alloy loaded cavity is used to generate multi-harmonic rf voltage in J-PARC RCS. However, a vacuum tube operation analysis under the multi-harmonic driving is very complicated because many variables should be solved with a self consistency. At the conventional operation analysis, a hand work by tracing the constant current curve of the tube was performed, or an appropriate single harmonic wave form was assumed. We have developed a numerical analysis code which calculates the vacuum tube operation automatically and it realizes the multi-harmonic vacuum tube operation analysis. The code is verified at the high power beam acceleration test and we confirm the calculation results are consistent with the measurement ones. We can calculate the vacuum tube operation precisely by using the code, and it will contribute to improving the quality of the beam in the high intensity proton synchrotron.
/D ion source for IFMIF (International Fusion Materials Irradiation Facility)Shinto, Katsuhiro; Sen
e, F.*; Ayala, J.-M.*; Bolzon, B.*; Chauvin, N.*; Gobin, R.*; Ichimiya, Ryo; Ihara, Akira; Ikeda, Yukiharu; Kasugai, Atsushi; et al.
Review of Scientific Instruments, 87(2), p.02A727_1 - 02A727_3, 2016/02
Times Cited Count：8 Percentile：39.15(Instruments & Instrumentation)Niimura, Nobuo; Arai, Shigeki; Kurihara, Kazuo; Chatake, Toshiyuki*; Tanaka, Ichiro*; Bau, R.*
Cellular and Molecular Life Sciences, 63(3), p.285 - 300, 2006/02
Times Cited Count：41 Percentile：37.86(Biochemistry & Molecular Biology)Neutron diffraction provides an experimental method of directly locating hydrogen atoms in proteins and DNA oligomers. Three different types of high resolution neutron diffractometers for biological macromolecules have been constructed in Japan, France and the U.S.A., and they have all been actively used in recent years to determine the crystal structures of numerous proteins. Examples include the detailed geometries of hydrogen bonds, information on H/D exchange in proteins, the unambiguous location of protons, the role of key hydrogen atoms in enzymatic activity and thermostability, and the dynamical behavior of hydration structures, all of which have been extracted from these structural results and reviewed in this article. Other important techniques, such as the optimization of growth of large single crystals using phase diagrams, the preparation of fully deuterated proteins, the introduction of cryogenic techniques to neutron protein crystallography, and the establishment of a "hydrogen and hydration in proteins" database, will also be described in this paper.
Hemsworth, R. S.*; Inoue, Takashi
IEEE Transactions on Plasma Science, 33(6), p.1799 - 1813, 2005/12
Times Cited Count：93 Percentile：92.94(Physics, Fluids & Plasmas)The positive or negative ion sources which form the primary components of neutral beam injection systems used in magnetic fusion have to meet simultaneously several demanding requirements. This paper describes the underlying physics of modern positive ion sources, which provide the required high proton fraction (
90%) and high current density (
2 kA/m
) at a low source pressure (0.4 Pa) with a high electrical efficiency and uniformity across the accelerator grids. The development of negative ion sources, which are required if high energy neutral beams are to be produced, is explained. The paper reports that negative ion sources have achieved many of the parameters required of sources for the neutral beam injectors of future fusion devices and reactors, 200 A/m of D
at low pressure, 
0.3 Pa, with low co-extracted electron content. The development needed to meet all the requiremens of future systems is briefly discussed.
Am and its EC-decay daughter 
PuAsai, Masato; Sakama, Minoru*; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.
European Physical Journal A, 23(3), p.395 - 400, 2005/02
Times Cited Count：16 Percentile：71.27(Physics, Nuclear)The EC decay of Am has been studied through 
-ray spectroscopy. Two EC-decaying states have been found in Am with half-lives of 3.6 min and 2.9 min. In Pu, we have found the 
octupole band and two-quasiparticle states one of which is a 
isomer with a 1.2 
s half-life. The EC transitions from Am to the two-quasiparticle states in Pu show small 
values of 4.8--5.3, which allowed us to assign proton-neutron configurations of Am and the two-quasiparticle states.
Futakawa, Masatoshi; Naoe, Takashi*; Kogawa, Hiroyuki; Ikeda, Yujiro
Journal of Nuclear Science and Technology, 41(11), p.1059 - 1064, 2004/11
Times Cited Count：12 Percentile：61.53(Nuclear Science & Technology)High power spallation targets for neutron sources are developing in the world. Mercury target will be installed at the material and life science facility in J-PARC, which will promote innovative science. The mercury target is subject to the pressure wave caused by the proton bombarding mercury. The pressure wave propagation induces the cavitation in mercury that imposes localized impact damage on the target vessel. The impact erosion is a critical issue to decide the lifetime of the target. The electric Magnetic Impact Testing Machine, MIMTM, was developed to produce the localized impact erosion damage and evaluate the damage formation. Acoustic vibration measurement was carried out to investigate the correlation between damage and acoustic vibration. It was confirmed that the acoustic vibration is useful to predict the damage due to the localized impact erosion and to diagnose the structural integrity.
Yoshizawa, Michio; Tanimura, Yoshihiko; Saegusa, Jun; Nemoto, Hisashi*; Yoshida, Makoto
Radiation Protection Dosimetry, 110(1-4), p.81 - 84, 2004/09
Times Cited Count：3 Percentile：23.52(Environmental Sciences)The facility of Radiation Standards (FRS) of JAERI has equipped with the concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an Am-Be (37GBq) neutron source placed in the narrow space surrounded by concrete wall and bricks to produce scattered neutrons. The neutron spectra of the fields were measured with Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters (RPCs), and a liquid scintillation counter (NE-213). The results were compared with each other, and the neutron spectra and the ambient dose equivalent rate, 
(10), were agreed well within the uncertainty. The angular distributions of neutron fluence were calculated by the MCNP-4B2 Monte Carlo code to obtain the reference personal dose equivalent rate, 
(10). The calculated results show that the scattered neutrons have a wide variety of incident angles. The reference (10) values considered the angular distribution were found to be 10-18% smaller than those without consideration.
Morishita, Takatoshi; Inoue, Takashi; Iga, Takashi*; Watanabe, Kazuhiro; Imai, Tsuyoshi
Review of Scientific Instruments, 75(5), p.1764 - 1766, 2004/05
Times Cited Count：8 Percentile：39.6(Instruments & Instrumentation)Negative ion beams of high current density are required for accelerator and fusion. The H source utilizes surface production that produces H from H or H
. And hence, high proto yield ion source is required. Generally, a large volume plasma generator with strong plasma confinement is suitable to achieve high proton yield. On the contrary, production of high proton ratio plasma is not easy in small sources. However, in a small source (3.5 liter), high current H beam of 800 A/m was obtained. In this research, the proton ratio was investigated experimentally and analytically in a small source (1.4 liter). The measured proton ratio increased form 40% to 90% by applying the magnetic filter. From the numerical analysis, the proton ratio is low as 40% in the driver region. However, with the magnetic filter, flow of primary electrons is restrained, resulting in suppression of H
production at the extraction region. In addition, molecular ions are easily destroyed by thermal electrons in the filter region. Thus the proton ratio is enhanced by the magnetic field in the small sources.
Watanabe, Kazuhiro; Iga, Takashi*; Morishita, Takatoshi; Kashiwagi, Mieko; Inoue, Takashi; Hanada, Masaya; Taniguchi, Masaki; Imai, Tsuyoshi
Proceedings of 28th Linear Accelerator Meeting in Japan, p.186 - 188, 2003/08
no abstracts in English
Morishita, Takatoshi; Inoue, Takashi; Iga, Takashi*; Watanabe, Kazuhiro; Kashiwagi, Mieko; Shimizu, Takashi; Taniguchi, Masaki; Hanada, Masaya; Imai, Tsuyoshi
JAERI-Tech 2003-007, 16 Pages, 2003/03
JAERI-Tech-2003-007.pdf:1.28MB
Recently the ion source for IFMIF (International Fusion Material Irradiation facility) achieved positive ion beams of 120 mA with the proton ratio of 90% by applying magnetic filter even in a small ion source. The mechanism of a high proton ration plasma production in such a small ion source has not been studied. Molecular ions are destroyed and the proton is produced from the dissociation of molecular ions in the filter region. Thus the proton yield is enhanced even in the small volume discharge. Using the same numerical method, the plasma production was calculated for the large ion source. The high proton ratio can be easily obtained, where the contribution of proton production by the ionization of H becomes high. From the negative ion production point of view, the negative ion beam current was numerically evaluated. The high atom flux to the plasma grid generates the large amount of negative ions rather than that by the positive ions in Cs-seeded large ion sources.
Nakashima, Hiroshi; Sakamoto, Yukio*; Tanaka, Shunichi; Tanaka, Susumu; Baba, Mamoru*; Nakamura, Takashi*; Hirayama, Hideo*; Shin, Kazuo*; JAERI-Universities Collaboration Working Group for Accelerator Shielding Study
Proceedings of 6th International Meeting on Nuclear Applications of Accelerator Technology (AccApp '03), p.959 - 968, 2003/00
In order to validate shielding design methods on proton accelerator facilities, a series of shielding experiments in several tens of MeV energy region were carried out at the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) of Japan Atomic Energy Research Institute (JAERI). The experiments include thick target neutron yield (TTY) measurements by charged particles, deep penetration experiments on concrete, steel and polyethylene shields using p-Li monoenergetic neutron source and radiation streaming experiment at a labyrinth of TIARA using p-Cu white neutron source. These experimental results are compared with calculation results with some high-energy particle transport codes such as MCNPX and NMTC/JAERI. The TTY measurements were analyzed by a code developed by Shin with a moving source model, and the streaming experiment was also analyzed by the DUCT-III code based on Shin's equation. This paper reviews the experimental results and the analyses on the results.
Yamamoto, Masanobu; Tamura, Fumihiko; Ezura, Eiji*; Hashimoto, Yoshinori*; Mori, Yoshiharu*; Omori, Chihiro*; Schnase, A.*; Takagi, Akira*; Uesugi, Tomonori*; Yoshii, Masahito*
Proceedings of 8th European Particle Accelerator Conference (EPAC 2002), p.1073 - 1075, 2002/00
Longitudinal beam emittance should be controlled to alleviate space charge effects by rf manipulations at 3 GeV proton synchrotrons in JAERI-KEK Joint High Intensity Proton Accelerator Project. At injection, bunching factor of 0.4 will be achived by controlled longitudinal beam painting and multiplying 2nd higher harmonics. Furthermore, heavy beam loading is a severe problem, and it should be compensated by feedforward method for stable acceleration. About these themes, the scenario will be described with particle tracking simulations.
Miyamoto, Naoki*; Seki, Masakazu; Kinsho, Michikazu; Oguri, Hidetomo; Okumura, Yoshikazu
JAERI-Tech 99-010, 27 Pages, 1999/02
no abstracts in English
Takada, Hiroshi; Yoshizawa, Nobuaki*; *
JAERI-Research 96-040, 91 Pages, 1996/08
JAERI-Research-96-040.pdf:2.2MB
no abstracts in English
Arakawa, Kazuo; Nakamura, Yoshiteru; Yokota, Wataru; Fukuda, Mitsuhiro; Nara, Takayuki; Agematsu, Takashi; Okumura, Susumu; Ishibori, Ikuo; *; Tanaka, Ryuichi; et al.
Proceedings of 13th International Conference on Cyclotrons and Their Applications, p.119 - 122, 1993/00
no abstracts in English
Okumura, Yoshikazu; Watanabe, Kazuhiro
JAERI-M 92-024, 23 Pages, 1992/03
no abstracts in English
Tachikawa, T.*; *; *; *; Nakamura, Yoshiteru; Yokota, Wataru; Fukuda, Mitsuhiro; Kamiya, Tomihiro; Agematsu, Takashi; Nara, Takayuki; et al.
Proceedings of the International Conference on Evolution in Beam Applications, p.270 - 274, 1992/00
no abstracts in English
