Details

Autor(en) / Beteiligte

• Umemoto, D
• Tsuchiya, H
• Enoto, T
• Yamada, S
• Yuasa, T
• Kawaharada, M
• Kitaguchi, T
• Nakazawa, K
• Kokubun, M
• Kato, H
• Okano, M
• Tamagawa, T
• Makishima, K

Titel

On-ground detection of an electron-positron annihilation line from thunderclouds

Ist Teil von

• Physical review. E, 2016-02, Vol.93 (2), p.021201-021201, Article 021201

Ort / Verlag

United States

Erscheinungsjahr

2016

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Thunderclouds can produce bremsstrahlung gamma-ray emission, and sometimes even positrons. At 00:27:00 (UT) on 13 January 2012, an intense burst of gamma rays from a thundercloud was detected by the GROWTH experiment, located in Japan, facing the Sea of Japan. The event started with a sharp gamma-ray flash with a duration of <300 ms coincident with an intracloud discharge, followed by a decaying longer gamma-ray emission lasting for ∼60 s. The spectrum of this prolonged emission reached ∼10 MeV, and contained a distinct line emission at 508±3(stat.)±5(sys.) keV, to be identified with an electron-positron annihilation line. The line was narrow within the instrumental energy resolution (∼80keV), and contained 520±50 photons which amounted to ∼10% of the total signal photons of 5340±190 detected over 0.1-10 MeV. As a result, the line equivalent width reached 280±40 keV, which implies a nontrivial result. The result suggests that a downward positron beam produced both the continuum and the line photons.