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和田 有希*; 松本 崇弘*; 榎戸 輝揚*; 中澤 知洋*; 湯浅 孝行*; 古田 禄大*; 米徳 大輔*; 澤野 達哉*; 岡田 豪*; 南戸 秀仁*; et al.
Physical Review Research (Internet), 3(4), p.043117_1 - 043117_31, 2021/12
In 2015 the Gamma-Ray Observation of Winter Thunderstorms (GROWTH) collaboration launched a mapping observation campaign for high-energy atmospheric phenomena related to thunderstorms and lightning discharges. This campaign has developed a detection network of gamma rays with up to 10 radiation monitors installed in Kanazawa and Komatsu cities, Ishikawa Prefecture, Japan, where low-charge-center winter thunderstorms frequently occur. During four winter seasons from October 2016 to April 2020, in total 70 gamma-ray glows, minute-lasting bursts of gamma rays originating from thunderclouds, were detected. Their average duration is 58.9 sec. Among the detected events, 77% were observed in nighttime. The gamma-ray glows can be classified into temporally-symmetric, temporally-asymmetric, and lightning-terminated types based on their count-rate histories. An averaged energy spectrum of the gamma-ray glows is well fitted with a power-law function with an exponential cutoff, whose photon index, cutoff energy, and flux are 0.613 
0.009, 4.68 0.04 MeV, and (1.013 0.003) 
10
erg cm
s
(0.2-20.0 MeV), respectively. The present paper provides the first catalog of gamma-ray glows and their statistical analysis detected during winter thunderstorms in the Kanazawa and Komatsu areas.
久富 章平*; 中澤 知洋*; 和田 有希*; 辻 結菜*; 榎戸 輝揚*; 篠田 太郎*; 森本 健志*; 中村 佳敬*; 湯浅 孝行*; 土屋 晴文
Journal of Geophysical Research; Atmospheres, 126(18), p.e2021JD034543_1 - e2021JD034543_12, 2021/09
被引用回数：15 パーセンタイル：80.71(Meteorology & Atmospheric Sciences)Around 17:00 on January 12, 2020 (UTC), radiation detectors installed at two locations with a 1.35 km separation in Kanazawa City, Japan, captured a total of four gamma-ray enhancements. The first pair was simultaneously observed at the two locations at 17:03 and were abruptly terminated by a lightning discharge. The remaining two enhancements were also nearly simultaneously observed 
3 min later, and one of them was also terminated by another lightning discharge. At the last termination, a downward terrestrial gamma-ray flash and a negative energetic in-cloud pulse were observed. Both pairs were associated with thundercloud cells. In the first pair, simultaneous detection in two locations 1.35 km apart suggests either a gamma-ray glow emerged in-between and time variability of its intensity were directly observed or there were two (or more) gamma-ray glows in the cell which reached the two detectors coincidentally. In the latter pair, the peak time in the downwind detector was 40 s later than that of the upwind detector. If the irradiation region moved with the cell, it would have taken 110 s. The discrepancy suggests either the glow moved 2.5 times faster than the cell or there were two (or more) glows in the cell. Also, the fact that the thunderstorm cell hosting the latter glows experienced the lightning discharge 3 min before suggests that the strong electric field in the cell can develop within a few minutes.
湯浅 孝行*; 和田 有希*; 榎戸 輝揚*; 古田 禄大; 土屋 晴文; 久富 章平*; 辻 結菜*; 奥田 和史*; 松元 崇弘*; 中澤 知洋*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2020(10), p.103H01_1 - 103H01_27, 2020/10
被引用回数：15 パーセンタイル：74.18(Physics, Multidisciplinary)We designed, developed, and deployed a distributed sensor network aiming at observing high-energy ionizing radiation, primarily gamma rays, from winter thunderclouds and lightning in coastal areas of Japan. Starting in 2015, we have installed, in total, more than 15 units of ground-based detector system in Ishikawa Prefecture and Niigata Prefecture, and accumulated 551 days of observation time in four winter seasons from late 2015 to early 2019. In this period, our system recorded 51 gamma-ray radiation events from thundercloud and lightning. Highlights of science results obtained from this unprecedented amount of data include the discovery of photonuclear reaction in lightning which produces neutrons and positrons along with gamma rays, and deeper insights into the life cycle of a particle-acceleration and gamma-ray-emitting region in a thunder-cloud. The present paper reviews objective, methodology, and results of our experiment, with a stress on its instrumentation.
大塚 紀彰; 松井 義典; 土谷 邦彦; 松井 哲也*; 有田 節男*; 和田 將平*
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05
東京電力福島第一原子力発電所で発生した事故を教訓に、過酷事故においても水位、水素濃度等を計測可能な機器の開発が求められている。特に、高温過酷環境においても使用可能な水素センサの開発は、水素爆発の防止の観点から必要不可欠である。本研究では、過酷環境下用計測機器の一環として、固体電解質を用いた水素濃度センサを開発し、過酷環境下における適用性の評価を目的とした特性試験を実施した。雰囲気温度400
Cにおける試験の結果、水素センサは水素濃度に応じた電圧を得られることを確認した。また雰囲気圧力01MPaの環境においても、水素濃度及び圧力変化に応じた電圧を得たことから、過酷環境下用計測機器としての見通しを得た。
大塚 紀彰; 松井 義典; 土谷 邦彦; 松井 哲也*; 有田 節男*; 和田 將平*
no journal, ,
東京電力福島第一原子力発電所事故における教訓を踏まえ、実用発電用原子炉の安全対策高度化に資する技術開発の一環として、過酷環境下でも測定可能な水素濃度センサの開発が必要不可欠である。本研究は、耐熱・耐放射線・耐圧性に優れた水素濃度センサを開発するために、固体電解質型水素濃度センサを選定し、高温環境下(室温700C)における水素濃度(0.013.5%)と起電力との関係を調べた。この結果、300700Cの範囲における水素濃度変化に対して、起電力が変化することを観測した。得られた起電力は、内部水素濃度を補正することにより、ネルンストの式と良い一致を示した。このことから、開発した固体電解質型水素濃度センサが、高温環境下における適用性を有するという見通しを得た。
