Correlations Between Secondary Cosmic Ray Rates and Strong Electric Fields at Lomnický štít

Abstract

Since March 2014, there is a continuous measurement of secondary cosmic rays by the detector system SEVAN (Space Environmental Viewing and Analysis Network) at Lomnický štít, altitude 2,634 m above sea level. Starting from June 2016, the count rates (1 s resolution) obtained from the three SEVAN detectors and from their coincidences are available, along with selected meteorological characteristics. Since 30 May 2016 the electric field measurements have been installed at the same site. Several events with clear increase of the count rate in the upper detector of SEVAN were observed during the thunderstorms until 17 September 2016. Examples of these measurements are presented and discussed. Barometric pressure correction and elimination of low‐frequency variability from the signal allow to extract 2 min averaged increases from the data. It is shown that the 2 min averaged increases of count rates measured by SEVAN correspond with periods of high electric field (with higher probability during negative polarity) rather than with the individual discharges (lightning).

Significant enhancements of secondary cosmic rays and electric field at the high mountain peak of Lomnický Štít in High Tatras during thunderstorms

“…In this experimental paper, observations of enhanced secondary cosmic ray fluxes-TGEs by the detector system SEVAN )-during measurements of large values of electric field at rocky mountain top of Lomnický Štít at the altitude of 2634 m in 2017 and 2018 are presented. The paper presents much stronger events compared to the previous study by Kudela et al (2017) that was mainly based on statistical investigation of TGEs recorded by the SEVAN channel 1 in 2016. The analysis of individual strong TGE events, likely caused by RREA, is the main focus of the paper.…”

“…The estimated energy threshold of the channel 1 for low energy charged particles (electrons, muons) is about 3.6 MeV (Chilingarian et al 2015). Considering the roof above the SEVAN detector, the effective energy threshold for channel 1 is estimated to be 7-8 MeV (Kudela et al 2017). The channel 1 is also partly sensitive to gamma-rays .…”

“…On the other hand, gamma-ray glows-often called thunderstorm ground enhancements (TGEs), if observed on the ground (Chilingarian and Mkrtchyan 2012)-are less intense emissions of much longer duration, usually of several minutes. The enhancement of gamma-rays with respect to the background level is usually not larger than several 10% for most of the TGE events (Dwyer and Uman 2014;Kudela et al 2017). However, TGEs that exceeded the background levels several times were also recorded (Chilingarian et al 2010).…”

“…However, TGEs that exceeded the background levels several times were also recorded (Chilingarian et al 2010). Another difference from TGFs is that TGEs are not associated with individual lightning; on the contrary, they are terminated if a nearby lightning occurs (Lidvansky 2003;Tsuchiya et al 2011;Kudela et al 2017). TGEs are correlated with high values of electric fields and it is hypothesized that they are Bremsstrahlung from relativistic runaway electron avalanches (RREA), suggested by Gurevich et al (1992).…”

“…TGEs are correlated with high values of electric fields and it is hypothesized that they are Bremsstrahlung from relativistic runaway electron avalanches (RREA), suggested by Gurevich et al (1992). TGEs are usually observed on high mountain peaks (Torii et al 2009;Tsuchiya et al 2009;Chilingarian et al 2011;Kudela et al 2017) or at low altitudes during winter thunderstorms along the Japanese coast (Torii et al 2002(Torii et al , 2011Tsuchiya et al 2011;Kuroda et al 2016). The TGEs were also observed in the mountain valley at Baksan observatory, North Caucasus, Russia (Lidvansky 2003;Khaerdinov et al 2005).…”