We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed.

We observe the new phenomenon of anomalous prolonged time distributions of neutron intensity using the 18NM64-type neutron monitor operating together with the shower installation of the Tian-Shan mountain cosmic ray station. We observe anomalous events in the core region of extensive air showers (EAS) with the size Ne > 106. The threshold of their generation coincides with the ‘knee’ in the energy spectrum of primary cosmic rays (about 3 × 1015 eV). The prolonged neutron events are accompanied by the flows of EAS electrons and γ-quanta having time distributions similar to those of the neutrons. The discovered phenomenon may be a reason to make a principal change in the usual procedure of EAS exploration.

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