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Takagi, Hirotaka*; Takagi, Rina*; Minami, Susumu*; Nomoto, Takuya*; Oishi, Kazuki*; Suzuki, Michito*; Yanagi, Yuki*; Hirayama, Motoaki*; Khanh, N.*; Karube, Kosuke*; et al.
Nature Physics, 19(7), p.961 - 968, 2023/07
Times Cited Count：8 Percentile：96.03(Physics, Multidisciplinary)Takagi, Rina*; Matsuyama, Naofumi*; Ukleev, V.*; Yu, L.*; White, J. S.*; Francoual, S.*; Mardegan, J. R. L.*; Hayami, Satoru*; Saito, Hiraku*; Kaneko, Koji; et al.
Nature Communications (Internet), 13, p.1472_1 - 1472_7, 2022/03
Times Cited Count：55 Percentile：99.61(Multidisciplinary Sciences)Harada, Hiroyuki; Meigo, Shinichiro; Shirakata, Masashi*; Sato, Yoichi*; Tamura, Fumihiko; Tejima, Masaki*; Hashimoto, Yoshinori*; Igarashi, Susumu*; Koseki, Tadashi
JPS Conference Proceedings (Internet), 8, p.012010_1 - 012010_6, 2015/09
The J-PARC 3-50BT line is the beam transport line from 3-GeV rapid-cycling synchrotron (RCS) to 50-GeV main ring (MR). The RCS is the high-intensity proton accelerator, where designed beam power is 1 MW, and has the complex source of space charge effect, etc. Therefore, the uncontrolled emittance growth and beam halo increase nonlinearly with the increasing the beam power. Additionally, the physical aperture of MR with 81 
mm mrad is smaller than that of RCS with 486 mm mrad. Therefore, the 3-50BT line has the collimators in order to remove the tail or halo of the extracted beam from the RCS. The designed collimator aperture is 54 mm mrad. It is required to measure and optimize the optics parameters in the collimator area for taking full advantage of the beam collimation. Especially, it is very important to make the dispersion functions free in the collimator area and optimize the beta function. This paper will introduce the method of optics measurement and report the result of the measurement and optimization based on the simulation.
Harada, Hiroyuki; Meigo, Shinichiro; Shirakata, Masashi*; Sato, Yoichi*; Tamura, Fumihiko; Tejima, Masaki*; Hashimoto, Yoshinori*; Igarashi, Susumu*; Koseki, Tadashi
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.39 - 43, 2014/06
The J-PARC 3-50 BT line is the beam transport line of extracted beam from 3-GeV rapid-cycling synchrotron (RCS) to 50-GeV main ring (MR). The RCS is the high-intensity proton accelerator, which designed beam power is 1 MW, and has the complex source of space charge effect, etc. Therefore, the uncontrolled emittance growth and beam halo increase nonlinearly with the increasing the beam power. Additionally, physical aperture of MR with 81 mm mrad is smaller than that of RCS with 486 mm mrad. Therefore, the 3-50 BT line has the collimators in order to scrape the tail/halo of extracted beam from the RCS. The designed collimator aperture is 54 mm mrad. It is required to measure and optimize the optics parameter in the collimator area for taking full advantage of beam collimation. This paper will introduce the method of optics measurement and report the result of the measurement and optimization based on the simulation.
reflector and proton beam windowTeshigawara, Makoto; Kinoshita, Hidetaka; Wakui, Takashi; Meigo, Shinichiro; Seki, Masakazu; Harada, Masahide; Ito, Manabu; Suzuki, Toru; Ikezaki, Kiyomi; Maekawa, Fujio; et al.
JAEA-Technology 2012-024, 303 Pages, 2012/07
JAEA-Technology-2012-024.pdf:46.04MB
3 GeV Protons with 1 MW beam power are irradiated to mercury target of spallation neutron source in Materials and Life science Facility (MLF), which is one of facilities of J-PARC. Irradiated components, such as target container, moderator, reflector and proton beam window, are needed to replace periodically due to irradiation damage of high energy protons and neutrons. These used components are replaced remotely because of highly activated. Maintenance scenario was settled so as to handle these components. Required remote handling machines were designed and installed in hot cell and other room of the MLF. We performed remote handling tests by using actual components to confirm the design. We report results, such as replacement procedure, trouble and its solution, etc., for moderator, reflector and proton beam window in order to provide the handling of actual used components.
Kinoshita, Hidetaka; Wakui, Takashi; Matsui, Hiroki; Maekawa, Fujio; Kasugai, Yoshimi; Haga, Katsuhiro; Teshigawara, Makoto; Meigo, Shinichiro; Seki, Masakazu; Sakamoto, Shinichi; et al.
JAEA-Technology 2011-040, 154 Pages, 2012/03
JAEA-Technology-2011-040.pdf:8.08MB
In the MLF, relatively high level irradiated components will be generated. Therefore, these components can not be kept in standard facilities. For the irradiated components at the MLF, the storage plan using the facilities in the Nuclear Science Research Institute has been studied, but the concrete plan is not decided yet. In this report, outline of the components, prehistory of the studying for storage, schedule of the component generation and status of the possible facility, which is a hot laboratory, are described. Resulting from the comparison between the generation schedule and the plan of the hot laboratory, the difference is very large. Present status of the hot laboratory and the cost estimation of the modification to use for storage of the MLF components were studied. Using the hot laboratory seems not to have advantage from the view point of cost and modification method. Therefore, the study on a new storage facility construction will be started as soon as possible.
Sakai, Kenji; Sakamoto, Shinichi; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; Naoe, Takashi; Kasugai, Yoshimi; Tatsumoto, Hideki; et al.
JAEA-Technology 2011-039, 121 Pages, 2012/03
JAEA-Technology-2011-039.pdf:10.87MB
This report investigates the behavior, damage and restoration of a neutron source station of the MLF at the Great East Japan Earthquake and verified the safety design for emergency accidents in the neutron source station. In the MLF, after an occurrence of the Earthquake, strong quakes were detected at the instruments, the external power supply was lost, all of the circulators shut down automatically, and the hydrogen gas was released. The leakages of mercury, hydrogen and radio-activation gases did not occur. While, the quakes made gaps between the shield blocks and ruptured external pipe lines by subsidence around the building. But significant damages to the components were not found though the pressure drop of compressed air lines influenced on a target trolley lock system and so on. These results substantiated the validity of the safety design for emergency accidents in the source station, and suggested several points of improvement.
Sakai, Kenji; Futakawa, Masatoshi; Takada, Hiroshi; Sakamoto, Shinichi; Maekawa, Fujio; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; et al.
Proceedings of 20th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-20) (USB Flash Drive), 6 Pages, 2012/03
This report investigates behaviors and damages of each component in a neutron target station of the MLF at the J-PARC at the time of the Great East Japan Earthquake (GEJE). At the date of the GEJE, in the MLF, strong quakes were detected at several instruments, an external power supply were lost, all of the circulation systems were shut down automatically, and a hydrogen gas was released as planned. Leakage of activation liquids and gases did not occur. While, the quakes made gaps between shield blocks and ruptured external pipe lines for air and water by subsidence. But significant damages on the components of the target station were not found though a loss of compressed air supply affected lock systems with air cylinders and pneumatic operation values. These results substantiated a validity of safety design on the target station for emergency accidents.
with an 
= 3/2 antiferromagnetic triangular sublatticeOkuda, Tetsuji*; Uto, Kazuma*; Seki, Shinichiro*; Onose, Yoshinori*; Tokura, Yoshinori*; Kajimoto, Ryoichi; Matsuda, Masaaki*
Journal of the Physical Society of Japan, 80(1), p.014711_1 - 014711_7, 2011/04
Times Cited Count：26 Percentile：76.24(Physics, Multidisciplinary)Mikami, Satoshi; Sato, Tetsuro; Seki, Akiyuki; Takemiya, Hiroshi; Matsumoto, Shinichiro; Saito, Kimiaki
no journal, ,
In Fukushima Prefecture and the prefectures in neighborhood, dose rate measurement by NaI(Tl) survaymeter, In situ measurement using a germanium semiconductor detector and investigation of depth distribution in soil using a scraper plate were conducted. The nuclides of Cs-137, Cs-134 and Ag-110m were detected in sufficiently many points to create a distribution maps by the in situ measurement. The values of dose rate measured by the surveymeters and the estimated ones by the in situ measurements with Ge detector showed good agreement. Averaged value of the estimated parameter 
was 1.17 g/cm
.
Mikami, Satoshi; Shimada, Kiyotaka; Nakano, Masakazu; Sato, Tetsuro; Sato, Akane; Uno, Kiichiro; Seki, Akiyuki; Matsumoto, Shinichiro; Saito, Kimiaki
no journal, ,
We conducted a monitoring and mapping of the radioactive substances distribution around the Fukushima Daiichi Nuclear Power Plant. In the area of 80 km radius from Fukushima Daiichi Nuclear Power Plant, 
measurements with portable Germanium detectors were conducted at approximately 380 points, and measurements with sureveymeters were done at approximately 6500 points. Newly acquired data were compared to the results obtained by the first or second investigation campaign in 2011.
-ray irradiation response of silicon carbide semiconductor devices; Extremely high radiation resistanceSato, Shinichiro; Onoda, Shinobu; Makino, Takahiro; Fujita, Natsuko; Oshima, Takeshi; Yokoseki, Takashi*; Tanaka, Kazuya*; Hijikata, Yasuto*; Tanaka, Yuki*; Kandori, Mikio*; et al.
no journal, ,
We investigate the threshold voltage shift of Si-MOSFETs, SiC-MOSFETs, SiC-MESFETs, and SiC SITs (Static Induction Transistors) due to irradiation. As a result, no significant threshold voltage shift was observed up to the absorbed dose of 10
Gy in all the SiC transistors, whereas the serious degradation was observed in the Si-MOSFETs. This strongly indicates that radiation resistance of SiC-MOSFETs and the other SiC-transistors is far superior to that of Si-MOSFETs. The radiation resistance of SiC-MOSFETs fabricated by pyrogenic oxidation is higher than that of the SiC-MOSFETs fabricated by dry oxidation. This result reflects that radiation resistance of SiC-MOSFETs strongly depends on the gate oxidation process since the formed oxide layers have different properties. Also, radiation resistance of SiC-SITs and SiC MESFETs is higher than that of SiC-MOSFETs, since SITs and MESFETs do not have gate oxide layer.
