Simulation of the Radiation Energy Release in Air Showers

TL;DR

This study uses simulations to analyze the MHz radiation energy released by air showers, establishing a quadratic relationship with electromagnetic energy and introducing an efficient extraction method with minimal uncertainty.

Contribution

It presents a novel, efficient method to extract radiation energy from air-shower simulations and characterizes its dependence on shower parameters.

Findings

Radiation energy scales quadratically with electromagnetic shower energy.

The method achieves a 4% intrinsic uncertainty in energy estimation.

Dependence on atmospheric density can be approximated using zenith angle.

Abstract

A simulation study of the energy released by extensive air showers in the form of MHz radiation is performed using the CoREAS simulation code. We develop an efficient method to extract this radiation energy from air-shower simulations. We determine the longitudinal profile of the radiation energy release and compare it to the longitudinal profile of the energy deposit by the electromagnetic component of the air shower. We find that the radiation energy corrected for the geometric dependence of the geomagnetic emission scales quadratically with the energy in the electromagnetic component of the air shower with a second order dependency on the atmospheric density at the position of the maximum of the shower development $X_\mathrm{max}$. In a measurement where $X_\mathrm{max}$ is not accessible, this second order dependence can be approximated using the zenith angle of the incoming direction of the air shower with only a minor deterioration in accuracy. This method results in an intrinsic uncertainty of 4% with respect to the electromagnetic shower energy which is well below current experimental uncertainties.