Simulation of Radiation Energy Release in Air Showers

TL;DR

This paper presents a simulation-based method to accurately estimate the electromagnetic energy in air showers through MHz radiation, revealing a quadratic scaling and minimal uncertainty, enhancing cosmic ray energy measurements.

Contribution

We develop an efficient simulation technique to extract radiation energy from air showers and establish its quadratic relation to electromagnetic energy, accounting for atmospheric density effects.

Findings

Radiation energy scales quadratically with electromagnetic energy.

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

Atmospheric density and zenith angle influence the radiation energy measurements.

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 dependence on the atmospheric density at the position of the maximum 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 loss in accuracy. Our method results in an intrinsic uncertainty of 4% in the determination of the energy in the electromagnetic air-shower component, which is well below current experimental uncertainties.