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Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
Hoshasen, 34(1), p.47 - 51, 2008/01
-ray dose-rate increase associated with thunderstorm activities was observed on the ground in winter. To investigate the fluctuation profile during winter thunderstorms, the energetic radiation was measured by using four set of radiation detectors (LPRCs) which consist of four long proportional counters (2.5 m in length; 10 cm in diameter). These LPRC have a different response characteristic for the incident particle by mounting shield covers. It was also compared with the result measured at the same time by the environmental radiation monitors adopting an NaI scintillator / ionization chamber as a detector. Moreover, the electric field was measured at the same site by using a field mill. In the observation from December, 2006 to February, 2007, the count-rate fluctuation which seem to originate from thunderstorm activity observed by the LPRCs.
Torii, Tatsuo; Okuyama, Shinichi; Nozaki, Tatsuo; Okubo, Koichi; Sugita, Takeshi*; Muraki, Yasushi*
Chimondai Ni Yoru Saiensu; Kyokugen Enerugi Uchubutsuri Kara Chikyukagaku Made, p.211 - 217, 2008/00
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. In addition to the measurement by the environmental radiation monitors set up around the fast breeder reactor, Monju, the radiation detectors were prepared which consist of the long proportional counters. The results were compared with the results measured at the same time by the environmental radiation monitors. The following two types of the radiation enhancements have been found during the winter thunderstorm activities; the gradual variation of photon intensity with energy up to 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. In this paper, we present the observed results during winter thunderstorms, and mention the runaway breakdown produced by the incidence of energetic radiation into thunderclouds.
Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
Proceedings of 30th International Cosmic Ray Conference (ICRC 2007), Vol.1, p.677 - 680, 2008/00
The dose rate increases of the -rays were observed on the ground in the winter season of Japan. To investigate the profile of the radiations during the winter thunderstorms, a four set of the radiation detectors was prepared which consists of the long proportional counters. These detectors have different characteristics of the response for the incident particle energies by mounting different thick shielding covers. Those results were compared with the results measured at the same time by the environmental radiation monitors set up around a nuclear power facility. Electric field was also measured by using a field mill. As a 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 are attributed to the injection of high energy photons with the energy over 10 MeV.
Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
Taiki Denki Gakkai-Shi, 1(2), p.73 - 74, 2007/00
The dose rate of the -rays increases in association with the activities of the winter thunderstorm. To investigate the time profile of the radiations during the winter thunderstorms, four sets of the radiation detectors were prepared which consist of the long proportional counters. Those results were compared with the results measured at the same time by the environmental radiation monitors set up around a nuclear power facility. Electric field was also measured by using a field mill. As a 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 10MeV.
Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
Taiki Denki Kenkyu, (69), p.30 - 31, 2006/00
no abstracts in English
Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
no journal, ,
Fluctuations of the energetic radiation at the thunderstorm activity are observed also on the ground. Such fluctuations during the winter thunderstorms were observed by using two long proportional counters (2.5m in length, diameter 10cm, X 4) in this research to investigate a more detailed fluctuation, besides the observation by the environmental radiation monitors set up around the nuclear facility Monju. In the observation from December, 2005 to January, 2006, the intense radiation thought to originate in the winter thunderstorm activity is observed four times. As a result, the followings have been obtained. (1) There were events that it increased gradually before several 10 seconds in which the rapid radiation burst is occurred. (2) When the transient increases of radiation intensity generated, the electric field strength was not fluctuated rapidly though the field strength fluctuate according to the lightning discharge had been occurred about 10-30 seconds after such radiation increases. (3) From the sensitivity evaluation of the long proportional counter by using RI sources and by a Monte Carlo calculation, the electron sensitivity was one order of magnitude higher than the ray sensitivity in the energy region over 3 MeV. As the results, it increased radiation intensity by the emission of the energetic electrons caused by the generation of runaway electrons in the thundercloud electric field.
Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
no journal, ,
-ray dose-rate increase associated with thunderstorm activities was observed on the ground at the west coast of Japan in winter. To investigate the fluctuation profile during thunderstorms, the energetic radiation was measured by using two radiation detectors which consist of four long proportional counters. The sensitivity of the counters for electrons with energy over 3 MeV has been an order of magnitude higher than that for -rays. From the results of the proportional counters and the other radiation monitors data, the transient increase of radiation is most likely caused by the incidence of the high energy electrons. It is considered that the runaway electrons have been emitted continuously for tens of seconds within such high fields and a portion of these electrons has reached the ground because the altitude of thundercloud is low in case of the winter thunderstorms.
Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
no journal, ,
Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
no journal, ,
The dose rate of the -rays increases in association with the activities of the thunderstorm. To investigate the time profile of the radiations during the winter thunderstorms, four sets of the radiation detectors were prepared which consist of the long proportional counters. These detectors have different characteristics of the response for the energy of the incident particles by mounting different thick shielding covers. Electric field was also measured by using a field mill. As a 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.
Torii, Tatsuo; Okuyama, Shinichi; Nozaki, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
no journal, ,
The dose rate might increase when the winter thunderstorm generated in the Sea of Japan coast has been generated. We report on events observed around Monju, and report this case on the radiation behavior in the thundercloud electric field thought about as a source of the radiation.
