Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ogiwara, Norio; Hikichi, Yusuke; Namekawa, Yuya; Kamiya, Junichiro; Kinsho, Michikazu; Hatanaka, Kichiji*; Shima, Tatsushi*; Fukuda, Mitsuhiro*
Proceedings of 7th International Particle Accelerator Conference (IPAC '16) (Internet), p.2102 - 2104, 2016/06
Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.706 - 708, 2015/09
no abstracts in English
Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Fukuda, Mitsuhiro*
Proceedings of 13th International Conference on Heavy Ion Accelerator Technology (HIAT 2015) (Internet), 3 Pages, 2015/09
no abstracts in English
Miyawaki, Nobumasa; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Fukuda, Mitsuhiro*
Proceedings of 13th International Conference on Heavy Ion Accelerator Technology (HIAT 2015) (Internet), 3 Pages, 2015/09
Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Taguchi, Mitsumasa; Fukuda, Mitsuhiro*
Review of Scientific Instruments, 86(7), p.073311_1 - 073311_8, 2015/07
Times Cited Count：13 Percentile：51.15(Instruments & Instrumentation)The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was modified to improve the quality and intensity of the single-pulse beam with pulse intervals over 1 
s at TIARA cyclotron facility of Japan Atomic Energy Agency. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. As a result, a contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1 %. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the TIARA cyclotron magnet. Provision of the high quality intense single-pulse beam contributes to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method.
Kamiya, Junichiro; Hikichi, Yusuke; Kinsho, Michikazu; Ogiwara, Norio; Fukuda, Mitsuhiro*; Hamatani, Noriaki*; Hatanaka, Kichiji*; Kamakura, Keita*; Takahisa, Keiji*
Journal of Vacuum Science and Technology A, 33(3), p.031605_1 - 031605_8, 2015/05
Times Cited Count：5 Percentile：22.94(Materials Science, Coatings & Films)For the vacuum systems of high-intensity beam accelerators, low radioactivation materials with good vacuum characteristics and high mechanical strength are required. The titanium alloy Ti-6Al-4V was investigated as a potential low activation vacuum material with high mechanical strength for the fabrication of vacuum components, particularly the flanges of beam pipes, in the J-PARC 3 GeV synchrotron. The dose rate of Ti-6Al-4V when irradiated by a 400 MeV proton was observed to decrease more rapidly than that of stainless steel. Furthermore, the generated radioactive isotopes were nuclides with relatively short half-lives. The outgassing rate of Ti-6Al-4V was the same as the typical value for stainless steel. Additionally, the hydrogen concentration in bulk Ti-6Al-4V was reduced to approximately 1 ppm by vacuum firing. These results indicate that Ti-6Al-4V is a good candidate for use as a low activation vacuum material with high mechanical strength.
Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro
Nuclear Instruments and Methods in Physics Research A, 767, p.372 - 378, 2014/12
Times Cited Count：3 Percentile：27.01(Instruments & Instrumentation)Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1179 - 1181, 2014/10
no abstracts in English
Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.500 - 502, 2014/06
no abstracts in English
Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Kurashima, Satoshi; Okumura, Susumu; Fukuda, Mitsuhiro*
Proceedings of 20th International Conference on Cyclotrons and their Applications (CYCLOTRONS 2013) (Internet), p.350 - 352, 2014/03
Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro
Nuclear Instruments and Methods in Physics Research A, 715, p.126 - 131, 2013/07
Times Cited Count：2 Percentile：19.73(Instruments & Instrumentation)An optimum condition for realizing phase bunching in the central region of a cyclotron was quantitatively clarified by a simplified geometric trajectory analysis of charged particles from the first to the second acceleration gap. The phase-bunching performance was evaluated for a general case of a cyclotron. The phase difference of incident particles at the second acceleration gap depends on the combination of four parameters: the acceleration harmonic number 
, the span angle 
of the dee electrode, the span angle 
from the first to the second acceleration gap, the ratio 
of the peak acceleration voltage between the cyclotron and ion source. Optimum values of for phase bunching were limited by the relationship between and , which is 90
/+/2 
180/+/2, and sin 
0. The phase difference with respect to the reference particle at the second acceleration gap is minimized for voltage-ratios between two and four for an initial phase difference within 40 RF degrees. Although the slope of the first acceleration gap contributes to the RF phase at which the particles reach the second acceleration gap, phase bunching was not affected. An orbit simulation of the JAEA AVF cyclotron verifies the evaluation based on geometric analysis.
Kurashima, Satoshi; Okumura, Susumu; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Sato, Takahiro; Kamiya, Tomihiro; Fukuda, Mitsuhiro*; Yokota, Wataru
Nuclear Instruments and Methods in Physics Research B, 306, p.40 - 43, 2013/07
Times Cited Count：2 Percentile：19.73(Instruments & Instrumentation)no abstracts in English
Kamiya, Junichiro; Ogiwara, Norio; Kinsho, Michikazu; Kamakura, Keita*; Hamatani, Noriaki*; Hatanaka, Kichiji*; Fukuda, Mitsuhiro*; Takahisa, Keiji*
Journal of the Vacuum Society of Japan, 56(5), p.167 - 171, 2013/05
no abstracts in English
Okumura, Susumu; Miyawaki, Nobumasa; Yuyama, Takahiro; Ishizaka, Tomohisa; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Ishibori, Ikuo; Yuri, Yosuke; Nara, Takayuki; et al.
Proceedings of 8th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.374 - 376, 2011/12
Reduction of the beam changing time is required to increase the available beam time for users. We are developing a technique for reducing the changing time of the magnetic field of the cyclotron, since it takes a long changing time to form the magnetic field for acceleration. Since the deviation of the magnetic field from the desired value for acceleration in the start-up process of the magnetic field dose not decrease in a short time, a correction system of the cyclotron magnetic field with a bipolar power supply and a 5-turn coil was developed. We confirmed that this system enables the magnetic field to be controlled quickly with a pc-based PID controller.
Kamiya, Tomihiro; Takano, Katsuyoshi; Sato, Takahiro; Ishii, Yasuyuki; Nishikawa, Hiroyuki*; Seki, Shu*; Sugimoto, Masaki; Okumura, Susumu; Fukuda, Mitsuhiro*
Nuclear Instruments and Methods in Physics Research B, 269(20), p.2184 - 2188, 2011/10
Times Cited Count：15 Percentile：73.97(Instruments & Instrumentation)Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Okumura, Susumu; Kashiwagi, Hirotsugu; Nara, Takayuki; Ishibori, Ikuo; Yoshida, Kenichi; Yokota, Wataru; Nakamura, Yoshiteru*; et al.
Nuclear Instruments and Methods in Physics Research A, 636(1), p.41 - 47, 2011/04
Times Cited Count：5 Percentile：38.65(Instruments & Instrumentation)A phase bunching effect has been achieved for the first time using a rising slope of the dee voltage waveform produced at the first acceleration gap between the RF shielding cover of the inflector and the puller in the new central region of the JAEA AVF cyclotron. The feasibility of the phase bunching effect in the central region for a two-dee system with a span angle of 86 in three acceleration harmonic modes was assessed by a simple geometrical analysis of particle trajectories and a three-dimensional beam orbit simulation. The simulation indicated that the initial beam phase width of 40 RF degrees is compressed to 11 RF degrees in the second harmonic mode. A phase width of 1.5 RF degrees FWHM for a 260 MeV 
Ne
beam accelerated in the second harmonic mode was reduced by the bunching effect, compared with the beam phase width of 7.3 RF degrees FWHM in the same harmonic mode for a 10 MeV H
beam accelerated in the original central region.
Iwamoto, Yosuke; Fukuda, Mitsuhiro*; Sakamoto, Yukio; Tamii, Atsushi*; Hatanaka, Kichiji*; Takahisa, Keiji*; Nagayama, Keiichi*; Asai, Hiroaki*; Sugimoto, Kenji*; Nashiyama, Isamu*
Nuclear Technology, 173(2), p.210 - 217, 2011/02
Times Cited Count：30 Percentile：89.69(Nuclear Science & Technology)The 30 white neutron beam at RCNP facility has been characterized as a prove suitable for testing of single event effects (SEEs) in semiconductors in the neutron energy range from 1 to 300 MeV using the 392-MeV proton incident reaction on a 6.5-cm-thick tungsten target. The neutron spectrum in measurements were demonstrated to provide a neutron spectrum similar to the terrestrial one at sea level, but with an enhancement in the intensity of a factor of 1.5
10
. The average neutron intensity and spectrum from 10 to 300 MeV at RCNP were almost same as those at WNR. The calculated RCNP neutron flux using PHITS generally agreed with the measured RCNP data within a factor of two. As the neutron density per pulse for RCNP is 500 times lower than that for WNR, the pileup probability of single-event transient currents and false multiple-bit upsets is reduced. Such conditions at RCNP are suitable for accelerated SEE testing to get meaningful results in realistic time frame.
Miyawaki, Nobumasa; Okumura, Susumu; Yuyama, Takahiro; Ishizaka, Tomohisa; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Ishibori, Ikuo; Yuri, Yosuke; Nara, Takayuki; et al.
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.975 - 978, 2010/08
The ratio of the beam changing time, which is the time for changing the operation condition of the cyclotron, to the whole operation time is large at the JAEA AVF cyclotron, since most irradiation time is short and frequent change of beams is required by users, mainly in materials science and biotechnology. In order to increase the efficiency of the use of the cyclotron, we are developing a technique for reducing the beam changing time, which is dominated by the start-up process of the magnetic field. A quick start-up process for the main magnetic field with a damping oscillation excitation allows to reduce the start-up time of the magnetic field.
Ishiyama, Atsushi*; Ueda, Hiroshi*; Fukuda, Mitsuhiro*; Hatanaka, Kichiji*; Miyahara, Nobuyuki*; Yokota, Wataru; Kashima, Naoji*; Nagaya, Shigeo*
Denki Gakkai Kenkyukai Shiryo, Chodendo Oyo Denryoku Kiki Kenkyukai (ASC-10-33), p.83 - 88, 2010/06
Therapy of tumor using radiation, especially heavy particle, is one of the effective treatment for an aged person and a malignant solid tumor. In order to spread the radiation therapy, downsizing of accelerator is necessary for reduction of its vast costs of construction and running. The quality of high temperature superconductors is improving rapidly in recent years, which may lead to realization of the downsizing. This presentation describes a conceptual design of the superconducting cyclotron and its advantage comparing to other type of accelerators.
Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05
Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.
