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Journal Articles

Negative muonium ion production with a C12A7 electride film

Otani, Masashi*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Matoba, Shiro*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Yamazaki, Takayuki*; Hasegawa, Kazuo; et al.

Journal of Physics; Conference Series, 1350, p.012067_1 - 012067_6, 2019/12

 Times Cited Count:0 Percentile:100

Negative muonium atom ($$mu^+$$e$$^-$$e$$^-$$, Mu$$^-$$) has unique features stimulating potential interesting for several scientific fields. Since its discovery in late 1980's in vacuum, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has relatively low-work function (2.9 eV). In this paper, the negative muonium production measurement with several materials including a C12A7 electride film will be presented. Measured production rate of the Mu$$^-$$ were 10$$^{-3}$$/s for all the Al, electride, and SUS target. Significant enhancement on electride target was not observed, thus it is presumed that the surface condition should be more carefully treated. There was no material dependence of the Mu$$^-$$ averaged energy: it was 0.2$$pm$$0.1keV.

Journal Articles

Discussion on translational research of drug product for targeted alpha therapy, 2

Yano, Tsuneo*; Hasegawa, Koki*; Sato, Tatsuhiko; Hachisuka, Akiko*; Fukase, Koichi*; Hirabayashi, Yoko*

Iyakuhin Iryo Kiki Regyuratori Saiensu, 50(3), p.122 - 134, 2019/03

This report provides an overview of alpha-particle-emitting radiopharmaceuticals applied by micro-dosimetry.

Journal Articles

First muon acceleration using a radio-frequency accelerator

Bae, S.*; Choi, H.*; Choi, S.*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Hasegawa, Kazuo; Iijima, Toru*; Iinuma, Hiromi*; Ishida, Katsuhiko*; Kawamura, Naritoshi*; et al.

Physical Review Accelerators and Beams (Internet), 21(5), p.050101_1 - 050101_6, 2018/05

 Times Cited Count:9 Percentile:13.16(Physics, Nuclear)

Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu$$^{-}$$), which are bound states of positive muons and two electrons, are generated from through the electron capture process in an aluminum degrader. The generated Mu$$^{-}$$'s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu$$^{-}$$'s are accelerated to 89 keV. The accelerated Mu$$^{-}$$'s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

Journal Articles

Retreat from stress; Rattling in a planar coordination

Suekuni, Koichiro*; Lee, C. H.*; Tanaka, Hiromi*; Nishibori, Eiji*; Nakamura, Atsushi*; Kasai, Hidetaka*; Mori, Hitoshi*; Usui, Hidetomo*; Ochi, Masayuki*; Hasegawa, Takumi*; et al.

Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03

 Times Cited Count:27 Percentile:7.87(Chemistry, Multidisciplinary)

Thermoelectric materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. In this paper, we studied the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)$$_{12}$$(Sb,As)$$_{4}$$S$$_{13}$$. The results revealed that the Cu atoms in a planar coordination are rattling, which effectively scatter phonons. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.

Journal Articles

Study on flaw-to-surface proximity rule for transforming subsurface flaws to surface flaws based on fatigue crack growth experiments

Hasegawa, Kunio; Li, Y.; Saito, Koichi*

Journal of Pressure Vessel Technology, 137(4), p.041101_1 - 041101_7, 2015/08

 Times Cited Count:3 Percentile:74.57(Engineering, Mechanical)

If a subsurface flaw is located near a component surface, the subsurface flaw is transformed to a surface flaw in accordance with a flaw-to-surface proximity rule. The re-characterization process from subsurface to surface flaw is adopted in all fitness-for-service (FFS) codes. However, the concrete criteria of the re-characterizations are different among the FFS codes. Cyclic tensile experiment was conducted on a carbon steel flat plate with a subsurface flaw at ambient temperature. The objective of the paper is to compare the experiment and calculation of fatigue crack growth behavior for a subsurface flaw and the transformed surface flaw, and to describe the validity of the flaw-to-surface proximity rule defined by ASME Code Section XI, JSME S NA1 Code and other codes.

Journal Articles

On-site background measurements for the J-PARC E56 experiment; A Search for the sterile neutrino at J-PARC MLF

Ajimura, Shuhei*; Bezerra, T. J. C.*; Chauveau, E.*; Enomoto, T.*; Furuta, Hisataka*; Harada, Masahide; Hasegawa, Shoichi; Hiraiwa, T.*; Igarashi, Yoichi*; Iwai, Eito*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(6), p.063C01_1 - 063C01_19, 2015/06

 Times Cited Count:1 Percentile:84.95(Physics, Multidisciplinary)

The J-PARC E56 experiment aims to search for sterile neutrinos at the J-PARC Materials and Life Science Experimental Facility (MLF). In order to examine the feasibility of the experiment, we measured the background rates of different detector candidate sites, which are located at the third floor of the MLF, using a detector consisting of plastic scintillators with a fiducial mass of 500 kg. The gammas and neutrons induced by the beam as well as the backgrounds from the cosmic rays were measured, and the results are described in this article.

Journal Articles

Beam test of a new radio frequency quadrupole linac for the Japan Proton Accelerator Research Complex

Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saishun; Hori, Toshihiko; Sawabe, Yuki; Chishiro, Etsuji; Fukuda, Shimpei; Hasegawa, Kazuo; Hirano, Koichiro; Kikuzawa, Nobuhiro; et al.

Physical Review Special Topics; Accelerators and Beams, 17(12), p.120101_1 - 120101_8, 2014/12

 Times Cited Count:5 Percentile:54.22(Physics, Nuclear)

We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.

Journal Articles

Present status of J-PARC linac

Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10

no abstracts in English

Journal Articles

JT-60SA assembly and metrology

Suzuki, Sadaaki; Yagyu, Junichi; Masaki, Kei; Nishiyama, Tomokazu; Nakamura, Shigetoshi; Saeki, Hisashi; Hoshi, Ryo; Sawai, Hiroaki; Hasegawa, Koichi; Arai, Takashi; et al.

NIFS-MEMO-67, p.266 - 271, 2014/02

no abstracts in English

Journal Articles

Assembly study for JT-60SA tokamak

Shibanuma, Kiyoshi; Arai, Takashi; Hasegawa, Koichi; Hoshi, Ryo; Kamiya, Koji; Kawashima, Hisato; Kubo, Hirotaka; Masaki, Kei; Saeki, Hisashi; Sakurai, Shinji; et al.

Fusion Engineering and Design, 88(6-8), p.705 - 710, 2013/10

 Times Cited Count:8 Percentile:36.38(Nuclear Science & Technology)

Journal Articles

High-power test and thermal characteristics of a new radio-frequency quadrupole cavity for the Japan Proton Accelerator Research Complex linac

Kondo, Yasuhiro; Morishita, Takatoshi; Hasegawa, Kazuo; Chishiro, Etsuji; Hirano, Koichiro; Hori, Toshihiko; Oguri, Hidetomo; Sato, Fumiaki; Shinozaki, Shinichi; Sugimura, Takashi*; et al.

Physical Review Special Topics; Accelerators and Beams, 16(4), p.040102_1 - 040102_8, 2013/04

 Times Cited Count:11 Percentile:33.22(Physics, Nuclear)

We performed a high-power test of a new radio-frequency quadrupole (RFQ II) for the J-PARC linac. RFQ II was developed as a spare RFQ because the operating J-PARC RFQ has suffered from a sparking problem. First, the conditioning of RFQ II was carried out; after 50 h of conditioning, RFQ II became very stable with a nominal power and duty of 330 kW and 3%, respectively. Next the thermal properties were measured because the resonant frequency of RFQ II is tuned by changing the temperature of the cooling water. The frequency response was measured and compared to finite-element method simulation results, confirming that the simple two-dimensional model reproduces the experimental data well. The differences in the field distribution with changes in the rf loading and the cooling-water temperature were also measured, and no serious field distortion was observed. Therefore, we conclude that RFQ II can perform well as a high-power rf cavity.

JAEA Reports

Plan for low level radioactive waste management

Kitamura, Koichi; Rindo, Hiroshi; Hasegawa, Makoto; Shimomura, Atsuhiko; Nuclear Cycle Backend Co-ordination Office

JAEA-Technology 2012-008, 57 Pages, 2011/11


The management plan is intended to summarize the process of Low level Radioactive Waste in JAEA from its generation to its treatment and disposal. Reasonable implementation of treatment and disposal for the radioactive waste on ensuring security was taken into account when the plan was made or updated based on the Framework for Nuclear Energy Policy made by Japan Atomic Energy Commission in 2005, the progress situation of laws and regulations, safety guides. Moreover, the issues to be solved during the process of implementation the plan were summarized, they will be studied in the plan, and then, its solutions will be reflected in the research program and project. JAEA will be carried out practical work for treatment and disposal of the radioactive waste based on the plan. Then, the updating will be made flexibly according to technology advance and progress situation of laws and regulations.

Journal Articles

Progress in ECRF antenna development for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Hasegawa, Koichi; Suzuki, Sadaaki; Hiranai, Shinichi; Sato, Fumiaki; Wada, Kenji; Yokokura, Kenji; Shimono, Mitsugu; Sawahata, Masayuki; et al.

Fusion Engineering and Design, 86(6-8), p.763 - 767, 2011/10

 Times Cited Count:6 Percentile:48.7(Nuclear Science & Technology)

Progress of antenna development of the Electron Cyclotron Range of Frequency system for JT-60 SA is presented. Capability of pulse length of 100 s, which requires active cooling for mirrors, and flexibility of beam injection angles in both poloidal and toroidal directions are required for the antenna with high reliability. Mechanical and structural design works of the launcher (antenna and its support with steering structure) based on a linear motion antenna concept are in progress. The key component is a long-stroke bellows which enables to alter poloidal injection angle and a bellows which enables to alter toroidal injection angle. Using a newly fabricated mock-up of the steering structure, it was confirmed that the antenna was mechanically realized for poloidal and toroidal injection angle ranges of -10 to +45$$^{circ}$$ and -15 to +15$$^{circ}$$, respectively. Those angles are consistent with angles required in JT-60SA. The results of thermal and structural analyses are also presented.

Journal Articles

Progress of high-power and long-pulse ECRF system development in JT-60

Kobayashi, Takayuki; Isayama, Akihiko; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Sato, Fumiaki; et al.

Nuclear Fusion, 51(10), p.103037_1 - 103037_10, 2011/10

 Times Cited Count:16 Percentile:35.46(Physics, Fluids & Plasmas)

A new gyrotron operation technique to increase oscillation efficiency was developed on the JT 60 ECRF system. The electron pitch factor was optimized by controlling anode voltage within 0.1 s after the start of the operation. By applying this technique, the gyrotron output power of 1.5 MW for 4 s was recorded, for the first time. The reduced collector heat load at 1.5 MW operations was reduced by 20% and it will be acceptable for longer pulse operation. A new gyrotron with an improved mode converter was developed in order to demonstrate reduction of the stray radiation which had limited the pulse length. The stray radiation was reduced to 1/3 of that of the original gyrotron. A conditioning operation of the improved gyrotron is proceeding up to 31 s at 1 MW. These progresses significantly contribute to enhancing the high power and long pulse capability of the ECRF system toward JT 60SA.

Journal Articles

Performance testing of vapor-liquid equilibrium type of gas permeation source with vacuum balance

Hatano, Toshihisa; Hiratsuka, Hajime; Hasegawa, Koichi; Kaifuku, Yuichiro*; Abe, Tetsuya

Journal of the Vacuum Society of Japan, 54(5), p.313 - 316, 2011/05

In the quantitative measure of air pollution gas and impurity gas in the aluminum recycle material etc, it is requested to show the amount of the gas directly by the weight value from the viewpoint of global standard. Therefore, standard gas sources expressed in units of weight are needed. The vapor-liquid equilibrium type of gas permeation sources (hereafter "P-tube") is used well in the atmosphere as calibration gas of the measuring equipment and a standard gas source for low concentration of gas. The study aims to estimate performance of P-tubes in the vacuum. Specifically, weight change of P-tubes were measured with the vacuum balance and at the same time concentration of gas constituents were also measured by Electron Ionization-Quadrupole Mass Spectrometer (hereafter, EI-QMS). The relation of both was examined. The prospect was obtained that the P-tube was able to be used as a standard gas source in the vacuum though the warming was needed.

JAEA Reports

Measures of the trouble on the long pulse in JT-60U electron cyclotron heating system

Hiranai, Shinichi; Suzuki, Sadaaki; Sato, Fumiaki; Kobayashi, Takayuki; Hasegawa, Koichi; Yokokura, Kenji; Moriyama, Shinichi

JAEA-Technology 2010-031, 24 Pages, 2010/09


The JT-60U electron cyclotron heating (ECH) system injects a millimeter wave at 110 GHz into the JT-60U plasma, and heats the plasma or drives a current locally to enhance the confinement performance of the JT-60U plasma. The ECH system of high power gyrotrons, transmission lines and antenna that launch millimeter wave beams toward the plasma. On the long pulse injection, one of the most important purposes is to prevent arcing in the transmission lines and to transmit millimeter wave beams efficiently. This report describes the problems occurred in a long pulse injection test (0.5 MW, 30 s), e.g., increase in released gas, temperature rise of the transmission line and an arcing at the vacuum window during the conditioning process. It also describes measures for the problems, e.g., improvements in vacuum pumping system, cooling system, and arc detector and introduction of the new dummy road system.

Journal Articles

Development of the long-pulse ECRF system for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Fasel, D.*; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; et al.

Journal of Plasma and Fusion Research SERIES, Vol.9, p.363 - 368, 2010/08

Improvements are required for expanding the pulse length of the JT-60 ECRF system (5s) for JT-60SA (100s). Newly developed power supplies will be fabricated and installed by EU. The conditioning operation of an improved gyrotron equipping a newly designed mode convertor has been started. The mode convertor will reduce heat flux on the internal components and therefore expected to enable long pulse operation at 1 MW. Pre-programmed and/or feedback control of the heater current and anode voltage, which was successfully demonstrated in JT-60U, will be key techniques because the beam current decreases during a shot. The evacuated transmission lines have a capability of 1 MW per line. Since maintenance of the components in the vacuum vessel is difficult, a linear motion antenna concept was proposed to reduce risks of water leakage and fault of the driving mechanism in the vacuum vessel. The detailed design and the low power test of a mock-up antenna have been started.

Journal Articles

ACS cavity for J-PARC LINAC

Ao, Hiroyuki; Asano, Hiroyuki; Ouchi, Nobuo; Tsubota, Naoaki; Hasegawa, Kazuo; Hirano, Koichiro; Morishita, Takatoshi; Takata, Koji*; Naito, Fujio*; Yamazaki, Yoshishige

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.552 - 554, 2010/08

The energy upgrade of the J-PARC linac was started from March 2009. In this project 20 Annular Coupled Structure (ACS) modules will be fabricated. The resonant frequency of the ACS module has to be tuned with mechanical machining before the final brazing. Therefore the test cells were fabricated to accumulate frequency tuning parameters. We fixed the final dimensions and the machining amount of the frequency tuning using these results. So far, the cell parts for the five ACS modules were tuned within 71.93 $$pm$$ 0.05 MHz. At the moment the first ACS module is being assembled and it will be completed in autumn 2010.

Journal Articles

Status of mass production of the ACS cavity for the J-PARC linac energy upgrade

Ao, Hiroyuki; Asano, Hiroyuki; Ouchi, Nobuo; Tsubota, Naoaki; Hasegawa, Kazuo; Hirano, Koichiro; Morishita, Takatoshi; Takata, Koji*; Naito, Fujio*; Yamazaki, Yoshishige

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.618 - 620, 2010/05

The mass production of the ACS (Annular-ring Coupled Structure) cavity started from March 2009 for the J-PARC linac energy upgrade from 181 MeV to 400 MeV. This upgrade project requires 18 ACS accelerating modules and two debunchers additionally within three years. The schedule is so tight that we have to optimize the fabrication process. Thus the test cells were fabricated for the all geometrical beta before the mass production to confirm the initial design and the frequency tuning procedure. This paper describes our approach for the mass production and the current status.

Journal Articles

Developments of high power gyrotron and power modulation technique using the JT-60U ECRF system

Kobayashi, Takayuki; Terakado, Masayuki; Sato, Fumiaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Hiranai, Shinichi; Igarashi, Koichi; et al.

Plasma and Fusion Research (Internet), 4, p.037_1 - 037_10, 2009/08

Electron cyclotron (EC) heating and current drive (CD) are key tools to control fusion plasma especially for effective electron heating and for suppression of neoclassical tearing mode (NTM). Recently, developments of a high power gyrotron and a power modulation technique have been successfully achieved on JT-60U ECRF system in order to enhance the system performance. Stable gyrotron oscillation with oscillation power of 1.5 MW for 1 s was demonstrated in 2007, for the first time. Then temperature rise of cavity and collector has been investigated. It has been shown that the longer pulse operation with 1.5 MW by an improved 110 GHz gyrotron is possible. In addition, modulated ECCD in synchronized with NTM rotation has been performed with the oscillation power of 0.8 MW and the frequency around 5 kHz. The synchronizing system has worked very well and it has played an essential role in NTM suppression experiments on JT-60U.

145 (Records 1-20 displayed on this page)