Abstract
The atmospheric electric fields in thunderclouds have been shown to significantly modify the intensity and polarization patterns of the radio footprint of cosmic-ray-induced extensive air showers. Simulations indicated a very non-linear dependence of the signal strength in the frequency window of 30-80 MHz on the magnitude of the atmospheric electric field. In this work we present an explanation of this dependence based on Monte-Carlo simulations, supported by arguments based on electron dynamics in air showers and expressed in terms of a simplified model. We show that by extending the frequency window to lower frequencies additional sensitivity to the atmospheric electric field is obtained.
Highlights
When a high-energy cosmic ray particle enters the upper layer of the atmosphere, it generates many secondary highenergy particles and forms a cosmic-ray-induced air shower
In this work we present an explanation of this dependence based on Monte Carlo simulations, supported by arguments based on electron dynamics in air showers and expressed in terms of a simplified model
We show that the influence of atmospheric electric fields can be understood from the dynamics of the electrons and positrons in the shower front as determined from Monte Carlo simulations using CORSIKA [26]
Summary
When a high-energy cosmic ray particle enters the upper layer of the atmosphere, it generates many secondary highenergy particles and forms a cosmic-ray-induced air shower Since these particles move with velocities near the speed of light, they are concentrated in the thin shower front extending over a lateral distance of the order of 100 m, called the pancake. The effect of the atmospheric electric field on each of the two driving mechanisms of radio emission, transverse current and charge excess, depends on its orientation with respect to the shower axis. There is no evidence that this expected change in the charge excess is reflected in a change in the radio emission as can be measured with the LOFAR LBAs. The component perpendicular to the shower axis, E⊥, does not affect the number of particles but changes the net transverse force acting on the particles.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
