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arXiv · 1811.06212

Mapping Observation Project of High-Energy Phenomena during Winter Thunderstorms in Japan

Yuuki Wada·Teruaki Enoto·Yoshihiro Furuta·Kazuhiro Nakazawa·Takayuki Yuasa·Takahiro Matsumoto·Daigo Umemoto·Kazuo makishima·Harufumi Tsuchiya·the GROWTH collaboration
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Abstract

The Gamma-Ray Observation of Winter Thunderclouds (GROWTH) collaboration has been performing observation campaigns of high-energy radiation in coastal areas of Japan Sea. Winter thunderstorms in Japan have unique characteristics such as frequent positive-polarity discharges, large discharge current, and low cloud bases. These features allow us to observe both long-duration gamma-ray bursts and lightning-triggered short-duration bursts at sea level. In 2015, we started a mapping observation project using multiple detectors at several new observation sites. We have developed brand-new portable gamma-ray detectors and deployed in the Kanazawa and Komatsu areas as well as the existing site at Kashiwazaki. During three winter seasons from 2015, we have detected 27 long-duration bursts and 8 short-duration bursts. The improved observation network in Kashiwazaki enables us to discover that the short-duration bursts are attributed to atmospheric photonuclear reactions triggered by a downward terrestrial gamma-ray flash. Collaborating with electric-field and radio-band measurements, we have also revealed a relation between abrupt termination of a long-duration burst and a lightning discharge. We demonstrate that the mapping observation project has been providing us clues to understand high-energy atmospheric phenomena associated with thunderstorm activities.

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Yuuki Wada, Teruaki Enoto, Yoshihiro Furuta, Kazuhiro Nakazawa, Takayuki Yuasa, Takahiro Matsumoto, Daigo Umemoto, Kazuo makishima, Harufumi Tsuchiya, the GROWTH collaboration. 2018-12-14. Mapping Observation Project of High-Energy Phenomena during Winter Thunderstorms in Japan. https://arxiv.org/abs/1811.06212

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