High energy photon and electron bursts associated with upward lightning strokes

[1] We conducted a field campaign during the Japanese winter thunderstorm season to observe radiation bursts associated with lightning discharges using a NaI scintillator and a thin plastic scintillator (PS), which primarily detects high energy electrons. We successfully recorded the bursts of high energy electrons with energies in excess of 100 keV from lightning discharges. We speculate that these high energy electrons were produced by high energy photon interactions near the PS. Our observations suggest that not only negative leaders but also positive leaders, which involve positive breakdowns, can cause an increase in the NaI count rate.