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Mikami, Satoshi; Tanaka, Hiroyuki*; Okuda, Naotoshi*; Sakamoto, Ryuichi*; Ochi, Kotaro; Uno, Kiichiro*; Matsuda, Norihiro; Saito, Kimiaki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 20(4), p.159 - 178, 2021/12
In order to know the background radiation level where the area affected by the Fukushima Daiichi Nuclear Power Plant accident in 2011, terrestrial gamma rays had been measured by using portable germanium detectors repeatedly from 2013 through 2019, at 370 locations within 80 km radius area centered on the Fukushima Daiichi Nuclear Power Plant. Radioactive concentrations of Uranium 238, Thorium 232, Potassium 40 and kerma rates in air due to terrestrial gamma rays were obtained at those locations based on the method of ICRU report 53. Averaged concentrations of U, Th and K were 18.8, 22.7, 428 Bq/kg, respectively, and kerma rate in air over the area was found to be 0.0402 Gy/h. The obtained kerma rates in air were compared to those reported in literatures. It was confirmed that the data were correlated with each other, and were agreed within the range of their uncertainty. This is because the kerma rate in air due to terrestrial gamma rays is depend on geology. The similar trend to previous findings was observed that the kerma rate in air at locations geologically classified as Mesozoic era, Granite and Rhyolite were statistically significantly higher than the others.
Sakamoto, Tetsuo*; Morita, Masato*; Kanenari, Keita*; Tomita, Hideki*; Sonnenschein, V.*; Saito, Kosuke*; Ohashi, Masaya*; Kato, Kotaro*; Iguchi, Tetsuo*; Kawai, Toshihide*; et al.
Analytical Sciences, 34(11), p.1265 - 1270, 2018/11
Times Cited Count:8 Percentile:32.37(Chemistry, Analytical)Tsuchiya, Tomoki*; Kobayashi, Ryota*; Kubota, Takahide*; Saito, Kotaro*; Ono, Kanta*; Ohara, Takashi; Nakao, Akiko*; Takanashi, Koki*
Journal of Physics D; Applied Physics, 51(6), p.065001_1 - 065001_7, 2018/02
Times Cited Count:8 Percentile:46.45(Physics, Applied)Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.
Nihon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00
no abstracts in English
Kobayashi, Riki*; Kaneko, Koji; Saito, Kotaro*; Mignot, J.-M.*; Andr, G.*; Robert, J.*; Wakimoto, Shuichi; Matsuda, Masaaki*; Chi, S.*; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 83(10), p.104707_1 - 104707_5, 2014/10
Times Cited Count:16 Percentile:68.66(Physics, Multidisciplinary)Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.
Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06
Times Cited Count:176 Percentile:99.41(Physics, Nuclear)Transverse momentum distributions and yields for , and in collisions at = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different collisions. We also present the scaling properties such as and scaling and discuss the mechanism of the particle production in collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.
Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.
Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04
Times Cited Count:7 Percentile:49.81(Physics, Nuclear)Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.
Yamamoto, Masahiro*; Uchiyama, Takashi*; Miyajima, Tsukasa*; Honda, Yosuke*; Sato, Kotaro*; Matsuba, Shunya*; Saito, Yoshio*; Kobayashi, Masanori*; Kurisu, Hiriki*; Hajima, Ryoichi; et al.
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.717 - 720, 2010/08
A 500-kV photocathode DC electron gun which can supply the beam of a low emittance and a high average current has been developed in collaboration with KEK, JAEA, Hiroshima Univ., Nagoya Univ. and Yamaguchi Univ. The vacuum of the gun chamber has to be lower Extreme High Vacuum for maintain cathode-life time. A titanium chamber and new material of ceramic were employed to reduce outgassing rate. The result of outgassing rate of the gun chamber is described in this report.
Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Uchiyama, Takashi*; Kobayashi, Masanori*; Muto, Toshiya*; Matsuba, Shunya*; Sakanaka, Shogo*; Sato, Kotaro*; Saito, Yoshio*; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.860 - 862, 2009/08
A newly 500 kV electron gun (2nd - 500 kV gun) for an ERL light source is designed at KEK. A new concept and state of-the-art technologies of vacuum system, ceramic insulators, high voltage power supply, photocathode and preparation system will be employed. The details are described in this report.
Murata, Yoshinori*; Shiraki, Atsuhiro*; Takeda, Kotaro*; Tsukada, Yuki*; Saito, Yoshihiro*; Morinaga, Masahiko*; Koyama, Toshiyuki*; Takaya, Shigeru
no journal, ,
no abstracts in English
Tomita, Hideki*; Saito, Kosuke*; Ohashi, Masaya*; Sonnenschein, V.*; Kato, Kotaro*; Suzuki, So*; Iguchi, Tetsuo*; Morita, Masato*; Sakamoto, Tetsuo*; Kanenari, Keita*; et al.
no journal, ,
no abstracts in English
Malins, A.; Ochi, Kotaro; Nakasone, Takamasa*; Yamada, Tsutomu*; Machida, Masahiko; Kurikami, Hiroshi; Saito, Kimiaki; Sanada, Yukihisa
no journal, ,
Here we report PHITS Monte Carlo simulations of a LaBr(Ce) gamma spectroscopy system used in unmanned helicopter radiation surveys in Fukushima Prefecture. The simulated spectra were verified against measurements taken under controlled laboratory conditions. Simulations were used to characterize the peak-to-Compton method for estimating the vertical distribution of radiocesium in soil from airborne surveys.
Hosoda, Masahiro*; Saito, Kimiaki; Mikami, Satoshi; Sanada, Tetsuya*; Omori, Yasutaka*; Takeda, Hikaru*; Yamada, Takahiro*; Hirao, Shigekazu*; Tani, Kotaro*; Orita, Makiko*; et al.
no journal, ,
no abstracts in English
Wakui, Takashi; Saito, Shigeru; Wakai, Eiichi; Sakai, Tomoki*; Mori, Kotaro*; Futakawa, Masatoshi
no journal, ,
One of dominant factors to determine the lifetime of the mercury target in J-PARC is the radiation damage. Authors suggested the tensile properties evaluation technique from numerical tensile tests using material properties estimated from inverse analyses on indentation tests. The technique was applied to ion-irradiated materials, and the validity of the technique was investigated by comparing the result with results of the PIE on the targets of SNS. By conducting indentation tests on samples cut out from used targets, it is expected that the residual lifetime estimation can be conducted considering various effects; fatigue, temperature, LME, etc. superimposed on the radiation damage from evaluating hardness and tensile properties obtained by the technique. The technique and comparison results will be discussed.
Sakai, Tomoki*; Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi; Mori, Kotaro*
no journal, ,
One of dominant factors to determine the lifetime of components used under the high-radiation environment is the radiation damage of materials and then understanding of the radiation damage is very important. Although ion irradiation has been conducted as the method simulating the radiation damage, the damaged area is limited to the surface layer of the specimen and has the gradient damage distribution. Micro-indentation tests with a Berkovich indenter were conducted in irradiated and unirradiated area on ion irradiated specimens and the micro-hardness was estimated from load and depth curve. The micro-hardness increased by the irradiation. The micro-hardness increased further under the irradiation condition that hydrogen ion and helium ion were added. On the other hand, the micro-hardness decreased with increasing irradiated temperature.
Saito, Fumihiro; Kasugai, Yoshimi; Seki, Kazunari; Nakane, Yoshihiro; Tani, Norio; Sato, Koichi; Yamazaki, Hirohito*; Bessho, Kotaro; Numajiri, Masaharu
no journal, ,
no abstracts in English
Sakai, Tomoki*; Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi; Mori, Kotaro*
no journal, ,
Radiation damage to materials is a factor that determines the lifetime of equipment used in high-radiation environments, and it is essential to understand the radiation damage. Ion irradiation has been used as a method of simulating irradiation damage, but the damage area is limited to the thin surface layer and has a gradient damage distribution. Therefore, micro-indentation test was applied as the method to investigating the mechanical properties and then the hardness in irradiated and unirradiated area. Increase of hardness due to irradiation was confirmed and the hardness increased by adding light ion. On the other hand, amount of increase in hardness decreased with increasing the irradiation temperature.
Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi; Sakai, Tomoki*; Mori, Kotaro*
no journal, ,
One of dominant factors to determine the lifetime of the structural components used under high irradiation environment is radiation damage. The indentation test will be applied to understand the degradation in mechanical properties. In this study, the technique evaluating mechanical properties from the combination of the indentation test with inverse analysis and the numerical tensile experiment is proposed. In order to confirm that this technique can evaluate changes in mechanical properties, it was applied to ion irradiated 316L stainless steels. The numerical model consists of multi layers whose mechanical properties are dependent on the DPA distribution. The material constants of each layer were identified. The numerical tensile experiments were conducted by using identified material constants. These results are compared with the PIE results of SNS. As the results, it was confirmed that this technique is effective to evaluate the mechanical property degradation due to irradiation.
Saito, Kotaro*; Yoneda, Yasuhiro; Matsuo, Hiroki*; Noguchi, Yuji*
no journal, ,
In addition to excellent piezoelectricity and dielectric properties, ferri-dielectric phases exhibit giant electric-field-induced strain due to the electric-field-induced phase transition. The presence of ferri-dielectric phase and its properties were investigated for (BiK)TiO-(BiLi)TiO (BKT-BLT) solid solution ceramics by searching for compositional phase boundaries and evaluating the composition dependence of polarization properties through crystal structure analysis. This study revealed that a ferri-dielectric phase exists around = 8% in the BKT-BLT solid solution system, and that a specifically high relative permittivity can be obtained at this composition.
Wakui, Takashi; Saito, Shigeru; Yamasaki, Kazuhiko*; Sakai, Tomoki*; Mori, Kotaro*; Futakawa, Masatoshi
no journal, ,
Irradiation damage due to protons and neutrons reduces ductility in the mercury target vessel of J-PARC. The radiation damage is one of the factors that determine the lifetime. The evaluation of the irradiation damage is extremely important for long-term operation at high beam power. A simple and rapid indentation technique is investigated in order to evaluate mechanical properties. Ion irradiation is a technique for simulating radiation damage, but the damage area is limited to the very surface layer. Therefore, we propose a mechanical property evaluation technique using an inverse analysis combining a Kalman filter and numerical experiments to the load-depth curve. As a result, changes in the mechanical properties due to ion irradiation were detected and it was confirmed that this evaluation technique was very effectiveness. In addition, the technique was applied to lead glass, and it was clarified that the microplastic behavior of glasses can be evaluated quantitatively.