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Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
JPS Conference Proceedings (Internet), 33, p.011050_1 - 011050_6, 2021/03
R&D of the beam window is crucial in the ADS, which serves as a partition between the accelerator and the target region. Although the displacement per atom (DPA) is used to evaluate the damage on the window, experimental data on the displacement cross section is scarce in the energy region above 20 MeV. We started to measure the displacement cross section for the protons in the energy region between 0.4 to 3 GeV. The displacement cross section can be derived by resistivity change divided by the proton flux and the resistivity change per Frankel pair on cryo-cooled sample to maintain damage. Experiments were conducted at the 3 GeV proton synchrotron at the J-PARC Center, and aluminum and copper was used as samples. As a result of comparison between the present experiment and the calculation of the NRT model, which is widely used for calculation of the displacement cross section, it was found that the calculation of the NRT model overestimated the experiment by about 3 times.
Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
Journal of Nuclear Science and Technology, 57(10), p.1141 - 1151, 2020/10
Times Cited Count：9 Percentile：75.92(Nuclear Science & Technology)To estimate the structural damages of materials in accelerator facilities, displacement per atom (dpa) is widely employed as a damage index, calculated based on the displacement cross-section obtained using a calculation model. Although dpa is applied as standard, the experimental data of the displacement cross-section for a proton in the energy region above 20 MeV are scarce. Among the calculation models, difference of about factor 8 exist, so that the experimental data of the cross-section are crucial to validate the model. To obtain the displacement cross-section, we conducted experiments at J-PARC. The displacement cross-section of copper and iron was successfully obtained for a proton projectile with the kinetic energies, 0.4 - 3 GeV. The results were compared with those obtained using the widely utilized Norgertt-Robinson-Torrens (NRT) model and the athermal-recombination-corrected (arc) model based on molecular dynamics. It was found that the NRT model overestimates the present displacement cross-section by 3.5 times. The calculation results obtained using with the arc model based on the Nordlund parameter show remarkable agreement with the experimental data. It can be concluded that the arc model must be employed for the dpa calculation for the damage estimation of copper and iron.
Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
EPJ Web of Conferences, 239, p.06006_1 - 06006_4, 2020/09
Times Cited Count：0 Percentile：0.1(Nuclear Science & Technology)R&D of the beam window is crucial in the ADS, which serves as a partition between the accelerator and the target region. Although the displacement per atom (DPA) is used to evaluate the damage on the window, experimental data on the displacement cross section is scarce in the energy region above 20 MeV. We started to measure the displacement cross section for the protons in the energy region between 0.4 to 3 GeV. The displacement cross section can be derived by resistivity change divided by the proton flux and the resistivity change per Frankel pair on cryo-cooled sample to maintain damage. Experiments were conducted at the 3 GeV proton synchrotron at the J-PARC Center, and copper was used as samples. As a result of comparison between the present experiment and the calculation of the NRT model, which is widely used for calculation of the displacement cross section, it was found that the calculation of the NRT model overestimated the experiment by about 3 times.
Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
JPS Conference Proceedings (Internet), 28, p.061004_1 - 061004_6, 2020/02
no abstracts in English
PtFukuda, Takashi*; Yamaguchi, Takashi*; Kakeshita, Tomoyuki*; Harjo, S.; Nakamoto, Tatsushi*
Journal of Applied Physics, 126(2), p.025107_1 - 025107_6, 2019/07
Times Cited Count：1 Percentile：4.41(Physics, Applied)Iwamoto, Yosuke; Matsuda, Hiroki; Meigo, Shinichiro; Satoh, Daiki; Nakamoto, Tatsushi*; Yoshida, Makoto*; Ishi, Yoshihiro*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Yashima, Hiroshi*; et al.
Proceedings of 61st ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2018) (Internet), p.116 - 121, 2018/07
The radiation damage model in the radiation transport code PHITS has been developed to calculate the basic data of the radiation damage including the energy of the target Primary Knock on Atom (PKA). For the high-energy proton incident reactions, a target PKA created by the secondary particles was more dominant than a target PKA created by the projectile. To validate the radiation damage model in metals irradiated by 
100 MeV protons, we developed a proton irradiation device with a Gifford-McMahon cryocooler to cryogenically cool wire samples. By using this device, the defect-induced electrical resistivity changes related to the DPA cross section of copper and aluminum were measured under irradiation with 125 and 200 MeV protons at cryogenic temperature. A comparison of the experimental data with the calculated results indicates that the DPA cross section with defect production efficiencies provide better quantitative descriptions.
Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Iwamoto, Hiroki; Hasegawa, Shoichi; Maekawa, Fujio; Yoshida, Makoto*; Ishida, Taku*; Makimura, Shunsuke*; Nakamoto, Tatsushi*
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.499 - 501, 2018/06
no abstracts in English
Sn strand at cryogenic temperatureHarjo, S.; Kawasaki, Takuro; Hemmi, Tsutomu; Ito, Takayoshi*; Nakamoto, Tatsushi*; Aizawa, Kazuya
JPS Conference Proceedings (Internet), 8, p.031001_1 - 031001_5, 2015/09
Nakamoto, Tatsushi*; Sugano, Michinaka*; Xu, Q.*; Kawamata, Hiroshi*; Enomoto, Shun*; Higashi, Norio*; Idesaki, Akira; Iio, Masami*; Ikemoto, Yukio*; Iwasaki, Ruri*; et al.
IEEE Transactions on Applied Superconductivity, 25(3), p.4000505_1 - 4000505_5, 2015/06
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)Recently, development of superconducting magnet system with high radiation resistance has been demanded for application in accelerator facilities such as CERN LHC. In order to realize superconducting magnet system with high radiation resistance, it is necessary to develop electrical insulator with high radiation resistance because the electrical insulator is made of organic materials whose radiation resistance is inferior to that of inorganic materials. We developed a glass fiber reinforced plastic with bismaleimide-triazine resin. The developed material showed excellent radiation resistance; the material evolved gases of 5
10 
mol/g and maintained flexural strength of 640MPa (90% of initial value).
Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.
Journal of Nuclear Materials, 458, p.369 - 375, 2015/03
Times Cited Count：13 Percentile：73.22(Materials Science, Multidisciplinary)To validate Monte Carlo codes for the prediction of radiation damage in metals irradiated by 100 MeV protons, defect-induced electrical resistivity changes of copper related to the displacement cross-section were measured with 125 MeV proton irradiation at 12 K. The cryogenic irradiation system was developed with a Gifford-McMahon cryocooler to cool the sample via an oxygen-free high-conductivity copper plate by conduction cooling. The sample was a copper wire with a 250
m diameter and 99.999% purity sandwiched between two aluminum nitride ceramic sheets. The resistivity increase did not change during annealing after irradiation below 15 K. The experimental displacement cross-section for 125 MeV irradiation shows similar results to the experimental data for 1.1 and 1.94 GeV. Comparison with the calculated results indicated that the defect production efficiency in Monte Carlo codes gives a good quantitative description of the displacement cross-section in the energy region 100 MeV.
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)Nakamoto, Tatsushi*; Ohata, Hirokatsu*; Ogitsu, Toru*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 31, 2007/02
Radiation resistance of organic materials used in superconducting magnets for a 50 GeV - 750 kW proton beam line for the J-PARC neutrino experiment was studied with respect to mechanical properties. Specimens cooled at a liquid nitrogen temperature of 77 K were irradiated by 
rays. The flexural strength of glass-fiber reinforced plastics (GFRPs), the tear strength of polyimide films and the tensile strength of adhesive films were evaluated. It was verified that the organic materials used in the superconducting magnets have the sufficient radiation resistance, and the degradation of thier mechanical properties after the 10 years operation was estimated to be negligible.
Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 32, 2007/02
Radiation resistance of polymeric materials used in the superconducting magnets installed for the J-PARC neutrino beam line was studied with respect to gas evolution. The polymeric materials were irradiated by rays at 77K. It was found that hydrogen gas evolved mainly from the polymeric materials, and the amount of hydrogen from whole superconducting magnet system per 1 year was estimated to be 0.37mol. This amount of hydrogen is low enough to be removed by a hydrogen absorbing apparatus. Therefore, the influence of hydrogen evolved from the magnet system on the operation of the helium purifying system can be negligible.
Makida, Yasuhiro*; Ohata, Hirokatsu*; Okamura, Takahiro*; Ogitsu, Toru*; Nakamoto, Tatsushi*; Kimura, Nobuhiro*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 34, 2007/02
A string of superconducting magnets is to be set at an arc section of the J-PARC neutrino beam line. To keep the magnets at superconducting condition, a helium cryogenic facility is to be constructed. Parts of cryogenic devices are located beside the magnets, so thier resistance to radiation with predicted dose of 1 MGy in maximum must be assured. A cryogenic control valve is one of the active devices used in the radio-active area, and its radio-proof characteristics is improved by (1) exchaging intolerant materials by proof ones, (2) moving the feed back control circuit unit including electronics from the valve body to a low radio-active area. Two prototype valves, a tuning valve and a Gauzky relief valve, have been prepared and have been tested by using the Cobalt 60 irradiation facility in JAEA. Actual operations of the both prototypes have been checked at the irradiation test bench, and they were successfully operated after irradiation of 1 MGy.
Idesaki, Akira; Morishita, Norio; Ito, Hisayoshi; Kamiya, Tomihiro; Nakamoto, Tatsushi*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Ogitsu, Toru*; Ohata, Hirokatsu*; Yamamoto, Akira*
AIP Conference Proceedings 824, p.330 - 334, 2006/03
Polyimide films and glass fiber reinforced plastics (GFRPs) are used as insulating or structural materials for superconducting magnets in a neutrino beam line of the Japan Proton Accelerator Research Complex (J-PARC). It is indispensable to evaluate radiation resistance of these materials, because they are required to keep their electrical and mechanical properties in a high radiation field of 30 kGy/year at low temperature of 4 K. In this work, the gas evolution resulting from chemical reactions induced in the polyimide films and GFRPs by ray irradiation at 77 K was investigated. It was found that the main component of the evolved gas is hydrogen. The amount of hydrogen evolved from the superconducting magnet system used in the neutrino beam line was estimated to be 0.37 mol/year (0.01 L/year as the volume of liquid hydrogen). It indicates that the hydrogen evolved from the organic materials does not influence on the operation of the helium purifying system.
Nakamoto, Tatsushi*; Idesaki, Akira; Morishita, Norio; Ito, Hisayoshi; Kamiya, Tomihiro; Kimura, Nobuhiro*; Makida, Yasuhiro*; Ogitsu, Toru*; Ohata, Hirokatsu*; Yamamoto, Akira*
AIP Conference Proceedings 824, p.225 - 232, 2006/03
Radiation resistance with respect to mechanical properties of organic materials used in the superconducting magnets for the 50 GeV - 750 kW proton beam line for the J-PARC neutrino experiment was studied. Specimens cooled at liquid nitrogen temperature of 77 K were irradiated by gamma rays beyond 10 MGy. The flexural strength of glass-fiber reinforced plastics (GFRPs), the tear strength of polyimide films and the tensile lap-shear strength of adhesive films were evaluated. It was verified that the organic materials used in the superconducting magnet have a sufficient radiation resistance, and the degradation of their mechanical properties after 10 years operation was estimated to be negligible.
Meigo, Shinichiro; Shigyo, Nobuhiro*; Iga, Kiminori*; Iwamoto, Yosuke*; Kitsuki, Hirohiko*; Ishibashi, Kenji*; Maehata, Keisuke*; Arima, Hidehiko*; Nakamoto, Tatsushi*; Numajiri, Masaharu*
AIP Conference Proceedings 769, p.1513 - 1516, 2005/05
For validation of calculation codes that are employed in the design of accelerator facilities, spectra of neutrons produced from a thick iron target bombarded with 1.5-GeV protons were measured. The calculated results with NMTC/JAM were compared with the present experimental results. It is found the NMTC/JAM generally shows in good agreement with experiment. Furthermore, the calculation gives good agreement with the experiment for the energy region 20 to 80 MeV, whereas the NMTC/JAM gives 50 % of the experimental data for the heavy nuclide target such as lead and tungsten target.
Meigo, Shinichiro; Takada, Hiroshi; Chiba, Satoshi; *; *; *; Maehata, Keisuke*; Shigyo, Nobuhiro*; Watanabe, Yukinobu*; Numajiri, M.*
Nuclear Instruments and Methods in Physics Research A, 431(3), p.521 - 530, 1999/00
Times Cited Count：38 Percentile：91.42(Instruments & Instrumentation)no abstracts in English
*; *; *; Shigyo, Nobuhiro*; Maehata, Keisuke*; Meigo, Shinichiro; Takada, Hiroshi; Chiba, Satoshi; Numajiri, M.*; Nakamura, Takashi*; et al.
Journal of Nuclear Science and Technology, 32(9), p.827 - 833, 1995/09
Times Cited Count：30 Percentile：92.13(Nuclear Science & Technology)no abstracts in English
Meigo, Shinichiro; Takada, Hiroshi; Chiba, Satoshi; *; *; *; Maehata, Keisuke*; Shigyo, Nobuhiro*; *; Watanabe, Yukinobu*; et al.
PSI-Proceedings 95-02, Vol. 2, 0, p.442 - 453, 1995/00
no abstracts in English
