Observation of gamma ray bursts at ground level under the thunderclouds

Abstract

We observed three $\gamma$-ray bursts related to thunderclouds in winter using the prototype of anti-neutrino detector PANDA made of 360-kg plastic scintillator deployed at Ohi Power Station at the coastal area of the Japan Sea. The maximum rate of the events which deposited the energy higher than $3$MeV was $(5.5\pm 0.1)\times 10^2/s$. Monte Carlo simulation showed that electrons with approximately monochromatic energy falling downwards from altitudes of order $100$m roughly produced the observed total energy spectra of the bursts. It is supposed that secondary cosmic-ray electrons, which act as seed, were accelerated in electric field of thunderclouds and multiplied by relativistic runaway electron avalanche. We actually found that the $\gamma$-rays of the bursts entered into the detector from the direction close to the zenith. The direction stayed constant during the burst within the detector resolution. In addition, taking advantage of the delayed coincidence detection of the detector, we found neutron events in one of the bursts at the maximum rate of $\sim 14\pm 5/s$.

16 pages, 7 figures; Accepted for publication in Physics Letters B; Figure 5 added, some minor changes in the text

References in corpus (6)

• Detection of high-energy gamma rays from winter thunderclouds
• Observation of an energetic radiation burst from mountain-top thunderclouds
• Reactor antineutrino monitoring with a plastic scintillator array as a new safeguards method
• Hardening and termination of long-duration gamma rays detected prior to lightning
• A mobile antineutrino detector with plastic scintillators
• Positron clouds within thunderstorms

Cited by in corpus (5)

• Photonuclear Reactions in Lightning Discovered from Detection of Positrons and Neutrons
• Termination of Electron Acceleration in Thundercloud by Intra/Inter-cloud Discharge
• Photoneutron Detection in Lightning by Gadolinium Orthosilicate Scintillators
• Catalog of Gamma-ray Glows during Four Winter Seasons in Japan
• Analysis of 42 years of Cosmic Ray Measurements by the Neutron Monitor at Lomnický stít Observatory