Atmospheric electric field effects on cosmic rays detected by the Solar Neutron Telescope at Sierra Negra

The influence of thunderstorms’ atmospheric electric fields (AEF) on secondary cosmic rays (CR) detected at high altitude was studied. Using data obtained during the period October 2019 to March 2020 by the Solar Neutron Telescope (SNT) and a Boltek EFM-100 AEF monitor installed in the Sierra Negra Cosmic Ray Observatory (SN-CRO) located at 4580 m a.s.l. in Mexico. With measurements from the EFM-100, 15 thunderstorms were identified during the established period. Based on the general theory of AEF effects on CR, due to acceleration and deceleration of secondary charged CR particles by AEF, proposed by Dorman (2004), we calculated, as a first approximation, the effect on the total charged component (1.15%–3.47%) at the observation level of the SN-CRO. Simulations of air showers in the presence of a simplified electric field were performed with the CORSIKA code and EXPACS software to complement the calculations. When thunderstorms occurred above SN-CRO, significant fluctuations in the average counting rate of three SNT channels were observed and were consistent with the calculated intensity variations.