title: Hardening and termination of long-duration γ rays detected prior to lightning.
abstract: We report the first observation of 3-30 MeV prolonged gamma-ray emission that was abruptly terminated by lightning. The gamma-ray detection was made during winter thunderstorms on December 30, 2010, by the Gamma-Ray Observation of Winter Thunderclouds experiment carried out in a coastal area along the Sea of Japan. The gamma-ray flux lasted for less than 3 min, continuously hardening closer to the lightning occurrence. The hardening at energies of 3-10 MeV energies was most prominent. The gamma-ray flux abruptly ceased less than 800 ms before the lightning flash that occurred over 5 km away from the experimental site. In addition, we observed a clear difference in the duration of the 3-10 MeV gamma rays and those >10 MeV, suggesting that the area of >10 MeV gamma-ray emission is considerably smaller than that of the lower-energy gamma rays. This work may give a manifestation that a local region emitting prolonged gamma rays connects with a distant region to initiate lightning.
authors.affiliation: Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tsuchiya
authors.forename: T
authors.initials: T
authors.lastname: Enoto
authors.forename: K
authors.initials: K
authors.lastname: Iwata
authors.forename: S
authors.initials: S
authors.lastname: Yamada
authors.forename: T
authors.initials: T
authors.lastname: Yuasa
authors.forename: T
authors.initials: T
authors.lastname: Kitaguchi
authors.forename: M
authors.initials: M
authors.lastname: Kawaharada
authors.forename: K
authors.initials: K
authors.lastname: Nakazawa
authors.forename: M
authors.initials: M
authors.lastname: Kokubun
authors.forename: H
authors.initials: H
authors.lastname: Kato
authors.forename: M
authors.initials: M
authors.lastname: Okano
authors.forename: T
authors.initials: T
authors.lastname: Tamagawa
authors.forename: K
authors.initials: K
authors.lastname: Makishima