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Kubota, Tomohiro; Kuroda, Hisao*; Watanabe, Mirai*; Takahashi, Akiko*; Nakazato, Ryoji*; Tarui, Mika*; Matsumoto, Shunichi*; Nakagawa, Keita*; Numata, Yasuko*; Ouchi, Takao*; et al.
Atmospheric Environment, 243, p.117856_1 - 117856_9, 2020/12
Times Cited Count：3 Percentile：15.82(Environmental Sciences)The dry and wet depositions of atmospheric ammonia (NH
) is one of the important pathways of nitrogen loads to aquatic ecosystems. Crop and livestock agriculture, one of the largest emitters of NH in Asian countries, are known to cause high spatial and seasonal variation of NH and influence the surrounding lake basin areas via its dry and wet deposition. However, the spatial characteristics of the NH concentration in basin scale are not completely understood for regulation in NH emission. Here we aim to clarify dominant factors of spatial and seasonal variations of the NH concentration in a eutrophic lake basin surrounded by agricultural areas in Japan. Passive sampling over various land use categories in the basin was conducted at 36 sites in total from October 2018 to January 2020. Interestingly, the observed NH concentration near the livestock houses were higher in winter than summer, which was inconsistent with knowledge of seasonal changes of current NH emission inventory based on temperature-driven volatilization process. Comparing monthly NH concentrations with various meteorological factors, we suggested the importance of seasonal advection of NH from high emission sources to which has been rarely paid attention by the previous past studies. As for this, should be considered for lake ecosystem management since deposition of NH is known to be closely related to the ecological processes such as phytoplankton blooming.
-ray detection to long-lived radioactive nuclide determination in environmental samplesOshima, Masumi*; Goto, Jun*; Haraga, Tomoko; Kin, Tadahiro*; Ikebe, Yurie*; Seto, Hirofumi*; Bamba, Shigeru*; Shinohara, Hirofumi*; Morimoto, Takao*; Isogai, Keisuke*
Journal of Nuclear Science and Technology, 57(6), p.663 - 670, 2020/06
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Gamma-gamma coincidence measurement utilized in -ray spectroscopy experiments is well known to be effective for the improvement of signal-to-noise ratio in a -ray spectrum. We study its applicability to determination of long-lived radioactive nuclides in environmental samples. The -ray simulation code Geant 4.10.2 was used. We took up 35 nuclides which need to be determined for the evaluation of fission product leakage at the nuclear accident in the Fukushima nuclear power plants. Among them five nuclides of 
Co, 
Nb, 
Cs, 
Eu and 
Eu can be the objectives of the multiple -ray detection method. The simulation results indicate that the signal-to-noise ratio can be improved by a factor between 9.8 and 283, and the detection limit by a factor between 2.7 and 8.5 relative to the singles measurement, implying that the method can be well applied to the determination of the long-lived radioactive nuclides.
Shoji, Eita*; Isogai, Shosei*; Suzuki, Rikuto*; Kubo, Masaki*; Tsukada, Takao*; Kai, Tetsuya; Shinohara, Takenao; Matsumoto, Yoshihiro*; Fukuyama, Hiroyuki*
Scripta Materialia, 175, p.29 - 32, 2020/01
Times Cited Count：19 Percentile：78.21(Nanoscience & Nanotechnology)
BOyamada, Akira*; Inohara, Takao*; Yamamoto, Etsuji; Haga, Yoshinori
Progress in Nuclear Science and Technology (Internet), 5, p.128 - 131, 2018/11
Ninomiya, Kazuhiko*; Kubo, Kenya*; Nagatomo, Takashi*; Higemoto, Wataru; Ito, Takashi; Kawamura, Naritoshi*; Strasser, P.*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Suzuki, Takao*; et al.
Analytical Chemistry, 87(9), p.4597 - 4600, 2015/05
Times Cited Count：28 Percentile：71.03(Chemistry, Analytical)Hayashi, Takao; Nishitani, Takeo; Sukegawa, Atsuhiko; Ishikawa, Masao; Shinohara, Koji
Review of Scientific Instruments, 79(10), p.10E506_1 - 10E506_3, 2008/10
Times Cited Count：6 Percentile：32.32(Instruments & Instrumentation)In D-D or D-T operation fusion devices, the fusion neutron yield is the most important parameter to estimate the fusion power. We have conducted calibrations of a microfission chamber, 14 mm in diameter and 200 mm in length, by both Cf-252 neutron source and real plasmas in JT-60U. The detector employs both pulse counting and Campbelling modes in the electronics to cover 10
dynamic range of the neutron source strength. The efficiencies were influenced by the various components. The point efficiencies can be integrated and averaged with angle to provide toroidal line efficiencies. The line efficiencies of microfission chamber and the nearest neutron monitor of U-235 fission chamber was 5.38 
10
and 1.77 10
, respectively. Then the calibration using real plasma was also performed. The detection efficiency in Campbelling mode was about three-tenth of the nearest neutron monitor, which is consistent with the calibration result using Cf-252 neutron source.
Ishikawa, Masao*; Itoga, Toshio*; Okuji, Toshio*; Nakhostin, M.*; Shinohara, Koji; Hayashi, Takao; Sukegawa, Atsuhiko; Baba, Mamoru*; Nishitani, Takeo
Review of Scientific Instruments, 77(10), p.10E706_1 - 10E706_3, 2006/10
Times Cited Count：22 Percentile：69.46(Instruments & Instrumentation)no abstracts in English
Sakurai, Shinji; Masaki, Kei; Shibama, Yusuke; Shinohara, Koji; Suzuki, Yutaka; Sasajima, Tadayuki; Morioka, Atsuhiko; Hayashi, Takao; Takahashi, Ryukichi; Sawai, Tomotsugu; et al.
no journal, ,
In order to reduce Toroidal magnetic Field (TF) ripple in JT-60U, ferritic steel (8Cr-2W-0.2V) armors were installed inside Vacuum Vessel (VV). 55 plates of 8Cr-2W-0.2V were manufactured from 2.6 ton ingots made by 20 ton vacuum induction melting. Saturated magnetization and thermal conductivity are 10-20% lower than those of F82H. Electrical resistivity and tensile properties are similar to those of F82H. 1122 carbon armors were replaced to 8Cr-2W-0.2V with reinforcement of stud nut. The absorbed beam power will be expected to increase 30%. A correction method of additional magnetic flux and field caused by 8Cr-2W-0.2V armors for magnetic probes is proposed for plasma position and shape control. Correction for flux loops is mostly good, but correcting model and program for B
probe need some improvements.
Hayashi, Takao; Nishitani, Takeo; Ishikawa, Masao; Shinohara, Koji; Morioka, Atsuhiko
no journal, ,
no abstracts in English
Eda, Itsumu*; Omine, Mayumi*; Nemoto, Norimasa*; Shimizu, Tomoko*; Tanaka, Sachiko*; Kashima, Takao*; Ito, Yukari*; Taniyama, Hiroshi*; Kamei, Mitsuru*; Yonezawa, Rika; et al.
no journal, ,
no abstracts in English
Sukegawa, Atsuhiko; Hayashi, Takao; Ishikawa, Masao*; Shinohara, Koji; Sakurai, Shinji; Masaki, Kei
no journal, ,
no abstracts in English
Ishikawa, Masao*; Itoga, Toshio*; Okuji, Toshio*; Nakhostin, M.*; Shinohara, Koji; Hayashi, Takao; Morioka, Atsuhiko; Baba, Mamoru*; Nishitani, Takeo
no journal, ,
no abstracts in English
Ishikawa, Masao; Itoga, Toshio*; Okuji, Toshio*; Baba, Mamoru*; Shinohara, Koji; Hayashi, Takao; Sukegawa, Atsuhiko
no journal, ,
no abstracts in English
Ishikawa, Masao; Itoga, Toshio*; Okuji, Toshio*; Nakhostin, M.*; Baba, Mamoru*; Shinohara, Koji; Hayashi, Takao; Sukegawa, Atsuhiko; Nishitani, Takeo
no journal, ,
Line-integrated neutron emission profiles are routinely measured using Stilbene neuron detectors (SNDs) in JT-60U tokamak. Although the SND has excellent pulse shape discrimination (PSD) property between neutrons and rays, the maximum count rate is limited up to 
10
cps due to its analog circuit. To overcome this issue, a digital signal processing (DSP) system using a flash ADC has been developed. In this system, anode signals from the photomultiplier of the SND are directory stored and digitized in the Flash ADC. Then, the PSD is performed using software. The DSP system has been installed in JT-60U and started to measure neutrons in deuterium experiments. As a result, it is confirmed that the DSP system is successfully measured neutron fluxes with count rate up to 10
cps.
Katata, Genki*; Kubota, Tomohiro; Kuroda, Hisao*; Watanabe, Mirai*; Takahashi, Akiko*; Nakazato, Ryoji*; Tarui, Mika*; Matsumoto, Shunichi*; Nakagawa, Keita*; Numata, Yasuko*; et al.
no journal, ,
no abstracts in English
