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Morishita, Yuki; Kaneko, Junichi*; Higuchi, Mikio*; Izaki, Kenji; Yajima, Tatsuo*; Matsuura, Mitsugu*; Tamura, Ken; Torii, Tatsuo
Radiation Measurements, 122, p.115 - 120, 2019/03
Times Cited Count:7 Percentile:62.49(Nuclear Science & Technology)Matsuura, Kohei*; Mizukami, Yuta*; Arai, Yuki*; Sugimura, Yuichi*; Maejima, Naoyuki*; Machida, Akihiko*; Watanuki, Tetsu*; Fukuda, Tatsuo; Yajima, Takeshi*; Hiroi, Zenji*; et al.
Nature Communications (Internet), 8, p.1143_1 - 1143_6, 2017/10
Times Cited Count:76 Percentile:91.69(Multidisciplinary Sciences)Torii, Tatsuo; Sugita, Takeshi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*
Geophysical Research Letters, 36(13), p.L13804_1 - L13804_4, 2009/07
Times Cited Count:53 Percentile:81.36(Geosciences, Multidisciplinary)Fluctuations of energetic radiation that seemed to be caused by a summer thunderstorm were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy rays having a continuous energy spectrum up to 10 MeV or more. As for the feature of these fluctuations, it seems naturally that such fluctuations are caused by the bremsstrahlung photons generated by the energetic electrons produced continuously with an intense electric field in the thundercloud rather than originated in the process of lightning discharge.
Torii, Tatsuo; Sugita, Takeshi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*
Taiki Denki Gakkai-Shi, 3(1), p.111 - 112, 2009/00
Fluctuations of energetic radiation that were seemed to be caused by a summer thunderstorm activity were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy rays having a continuous energy spectrum up to 10 MeV or more. As for the feature of these fluctuations, it seems naturally that such fluctuations are caused by the bremsstrahlung photons generated by the runaway electrons produced continuously with an intense electric field in the thundercloud rather than originated in the process of lightning discharge.
Torii, Tatsuo; Sugita, Takeshi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*
no journal, ,
Fluctuations of energetic radiation that were seemed to be caused by a summer thunderstorm activity were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy rays having a continuous energy spectrum up to 10 MeV or more. As for the feature of these fluctuations, it seems naturally that such fluctuations are caused by the bremsstrahlung photons generated by the runaway electrons produced continuously with an intense electric field in the thundercloud rather than originated in the process of lightning discharge. The 5-inch NaI detector used in the observation was so sensitive to photons that it could not have differentiated electrons from photons even if high-energy electrons had been incident upon the detector. When conducting the analysis of energy spectrum, sufficient convergence was achieved in the calculation even in the case where only the sensitivity to photons was considered.
Torii, Tatsuo; Yasuda, Hiroshi*; Yajima, Kazuaki*; Sugita, Takeshi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*
no journal, ,
Fluctuations of energetic radiation that were seemed to be caused by a summer thunderstorm were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy rays having a continuous energy spectrum up to 10 MeV or more. As for the feature of these fluctuations, it seems naturally that such fluctuations are caused by the bremsstrahlung photons generated by the energetic electrons produced continuously with an intense electric field in the thundercloud rather than originated in the process of lightning discharge.
Torii, Tatsuo; Sugita, Takeshi*; Tsuchiya, Harufumi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*
no journal, ,
The dose rate of the -rays increases in association with the activities of the thunderstorm. They were observed on the ground in the winter season of Japan. As an observed result, the following two types of the radiation enhancements have been found during the winter thunderstorm activities; the gradual variation of photon intensity with energy of a few MeV, and the burst type of the radiation that is attributed to the injection of high energy photons with the energy over 10 MeV. Furthermore, fluctuations of energetic radiation that were seemed to be caused by a summer thunderstorm activity were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy rays having a continuous energy spectrum up to 10 MeV or more.
Morishita, Yuki; Kaneko, Junichi*; Izaki, Kenji; Yajima, Tatsuo*; Matsuura, Mitsugu*
no journal, ,
For detecting airborne contamination of Pu and Pu released by the accident, a dust monitor with a silicon surface barrier detector (SSBD) is introduced at a site of nuclear fuel facility. However, SSBD frequently produces a false alarm triggered by an electromagnetic noise generator. For high-reliable dust monitoring, we developed an particle spectrometer based on the GPS scintillator plate with PMT. Our developed spectrometer consists of a cerium doped GdSiO (GPS) scintillator plate and a Photomultiplier Tube (PMT). The GPS scintillator plate was hexagonal in shape and 50 mm in diameter and a scintillator layer was approximately 40 um. An Am source with 5.5 MeV particle, Rn progeny collected air filter, and PuO particle were measured by developed spectrometer. The energy resolution for 5.5-MeV particles was 11.9% FWHM. The radon progeny nuclide reduction ratio (Rratio) was improved compared with ZnS(Ag) based spectrometer, so that Pu and Rn progeny can be effectively distinguished. Thus, our developed spectrometer will be high-reliable dust monitor for detecting Pu contamination.
Sato, Rina; Yoshimura, Kazuya; Sanada, Yukihisa; Yajima, Kazuaki*; Aono, Tatsuo*
no journal, ,
no abstracts in English