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 $(5.5 \pm 0.1) \times 10^2 {\rm /s}$. 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 $\sim 14\pm5\,{\rm /s}$.Comment: 16 pages, 7 figures; Accepted for publication in Physics Letters B; Figure 5 added, some minor changes in the tex

Radiocarbon Production by Thunderstorms

“…The first, with null result, attempt (Fleisher, ) to detect thunderstorm‐related neutrons was followed by communications claiming neutron flux enhancements in thunderstorms (Bratolyubova‐Tsulukidze et al, ; Chilingarian et al, , , , , ; Gurevich et al, ; Ishtiaq et al, ; Kuroda et al, ; Kuzhewskiĭ, ; Martin & Alves, ; Shah et al, ; Shyam & Kaushik, ; Starodubtsev et al, ). Possibly, after Libby and Lukens the neutron generation in thunderstorms was related to reactions in lightning channels (Fleisher, ; Kuzhewskiĭ, ; Shah et al, ; Shyam & Kaushik, ).…”

“…However, the energy of deuterons in lighting channels is too low for these reactions to occur (Babich, , ; Babich, ; Babich et al, ; Babich & Roussel‐Dupré, ). As bright terrestrial γ ray flashes (TGFs) with duration Δt γ on the order of 1 ms, detected in near space (Briggs et al, ; Connaughton et al, ; Fishman et al, ; Marisaldi, Fuschino et al, ; Marisaldi, Tavani et al, ; Smith et al, ; Tavani et al, ), aboard aircraft (Smith et al, ) and at the ground (Tran et al, ), and prolonged γ bursts (Δt γ up to 10 min) detected on the ground (Chilingarian et al, , , , , ; Khaerdinov, Lidvansky, & Petkov, ; Kuroda et al, ; Torii et al, ; Tsuchiya et al, , , , ) are correlated with thunderstorms and their spectra extend up to 100 MeV (Tavani et al, ), i.e., high above the thresholds ε th, N = 10.55 MeV and ε th, O = 15.7 MeV of photonuclear , and electro‐disintegration , …”

“…In view of the shortcomings in Babich and Roussel‐Dupré () and given new experimental (Briggs et al, ; Chilingarian et al, , , , , ; Connaughton et al, ; Cummer et al, , ; Gurevich et al, ; Ishtiaq et al, ; Kelley et al, ; Kuroda et al, ; Marisaldi, Fuschino et al, ; Marisaldi, Tavani et al, ; Martin & Alves, ; Starodubtsev et al, ; Tavani et al, ; Tsuchiya et al, , , , ) and computational (Babich, ; Babich et al, , ; Babich, Bochkov, Kutsyk et al, ; Babich, Bochkov, Donskoĭ et al, ; Babich, Bochkov, Kutsyk et al, ; Babich, Bochkov, Dwyer et al, ; Babich et al, ; Carlson et al, ; Celestin, Xu, & Pasko, ; Dwyer, ; Dwyer, Grefenstette, & Smith, ; Kelley et al, ; Tsuchiya et al, ; Xu, Celestin, & Pasko, ) data on thunderstorm γ rays and neutrons, reanalyzing of the problem of the production by thunderstorms is expedient. The new analysis is based not on a limited number of detections of thunderstorm neutrons as in Babich and Roussel‐Dupré () but on a vast amount of new data obtained from detecting of thunderstorm ground enhancements, i.e., enhanced fluxes of high‐energy electrons, hard γ rays, and neutrons on the Earth's surface, which have been copiously collected on Mount Aragats, Armenia (3250 m above sea level) (Chilingarian et al, , , , , ) and at other sites worldwide: Japan (sea level and 2770 m above sea level) (Tsuchiya et al, , , ); Tibet, China (4300 m above sea level) (Tsuchiya et al, ); Himalayas, India (2743 m above sea level) (Ishtiaq et al, ; Shah et al, ); and Tien Shan, Kazakhstan (3340 m above sea level) (Gurevich et al,…”

“…However, the energy of deuterons in lighting channels is too low for these reactions to occur (Babich, 2006(Babich, , 2007Babich, 2014;Babich et al, 2014;Babich & Roussel-Dupré, 2007). As bright terrestrial γ ray flashes (TGFs) with duration Δt γ on the order of 1 ms, detected in near space (Briggs et al, 2010;Connaughton et al, 2011;Fishman et al, 1994;Marisaldi, Fuschino et al, 2010;Smith et al, 2005;Tavani et al, 2011), aboard aircraft and at the ground (Tran et al, 2015), and prolonged γ bursts (Δt γ up to 10 min) detected on the ground (Chilingarian et al, 2010(Chilingarian et al, , 2012(Chilingarian et al, , 2013(Chilingarian et al, , 2016(Chilingarian et al, , 2017Khaerdinov, Lidvansky, & Petkov, 2005;Kuroda et al, 2016;Torii et al, 2009;Tsuchiya et al, 2007Tsuchiya et al, , 2009Tsuchiya et al, , 2011Tsuchiya et al, , 2012 are correlated with thunderstorms and their spectra extend up to 100 MeV (Tavani et al, 2011), i.e., high above the thresholds ε th, N = 10.55 MeV and ε th, O = 15.7 MeV of photonuclear 14 7 N þ γ→ 13 7 N þ n, 16 8 O þ γ→ 15 8 O þ n and electro-disintegration 14 7 N þ e À þ ε e → 13 7 N þ n þ e À , 16 8 O þ e À þ ε e → 15 8 O þ n þ e À reactions; these reactions are the most obvious processes accounting for the thunderstorm neutrons (Babich, 2006(Babich, , 2007(Babich, , 2014Babich et al, 2014;Babich & Roussel-Dupré, 2007;Carlson, Lehtinen, & Inan, 2010;Chilingarian et al, 2010Chilingarian et al, , 2012. As the thunderstorm γ rays are the bremsstrahlung of relativistic runaway electron avalanches, capable of developing in thundercloud electric fields…”

“…Babich and Roussel-Dupré (2007) concluded that thunderstorm neutrons nowadays deposit weakly into the 14 6 C concentration on average across the globe, but locally, especially in tropics, the 14 6 C production by thunderstorms, possibly, compete with that by cosmic irradiation. In view of the shortcomings in Babich and Roussel-Dupré (2007) and given new experimental (Briggs et al, 2010;Chilingarian et al, 2010Chilingarian et al, , 2012Chilingarian et al, , 2013Chilingarian et al, , 2016Chilingarian et al, , 2017Connaughton et al, 2011;Cummer et al, 2005Cummer et al, , 2011Gurevich et al, 2012;Ishtiaq et al, 2016;Kelley et al, 2015;Kuroda et al, 2016;Marisaldi, Fuschino et al, 2010;Martin & Alves, 2010;Starodubtsev et al, 2012;Tavani et al, 2011;Tsuchiya et al, 2007Tsuchiya et al, , 2009Tsuchiya et al, , 2011Tsuchiya et al, , 2012 and computational (Babich, 2014;Babich et al, , 2008Babich, Bochkov, Donskoĭ et al, 2010;Babich, Bochkov, Dwyer et al, 2013;Babich et al, 2014;Carlson et al, 2010;Dwyer, 2008;Dwyer, Grefenstette, & Smith, 2008;Kelley et al, 2015;Tsuchiya et al, 2012; data on thunderstorm γ rays and neutrons, reanalyzing of the problem of the 14 6 C production by thunderstorms is expedient. The new analysis is based not on a limited number of detections of thunderstorm neutrons as in Babich and Roussel-Dupré (2007) but on a vast amount of new data obtained from detecting of thunderstorm ground enhancements, i.e., enhanced fluxes of high-energy electrons, hard γ rays, and neutrons on the Earth's surface, which ha...…”