Macroscopic Model of Geomagnetic-Radiation from Air Showers, II

TL;DR

This paper develops a macroscopic model of radio emission from air showers, linking the emission properties to shower profiles and demonstrating how radio signals can differentiate between proton and iron primaries.

Contribution

It introduces a macroscopic, intuitive framework for understanding radio emission from air showers and its dependence on shower composition and structure.

Findings

Radio emission reflects the shower profile.

Higher frequencies show suppressed emission.

Radio signals can distinguish primary particle types.

Abstract

The generic properties of the emission of coherent radiation from a moving charge distribution are discussed. The general structure of the charge and current distributions in an extensive air shower are derived. These are subsequently used to develop a very intuitive picture for the properties of the emitted radio pulse. Using this picture can be seen that the structure of the pulse is a direct reflection of the shower profile. At higher frequencies the emission is suppressed because the wavelength is shorter than the important length scale in the shower. It is shown that radio emission can be used to distinguish proton and iron induced air showers.