Simulations of reflected radio signals from cosmic ray induced air showers

TL;DR

This paper models the coherent radio signals reflected from cosmic ray air showers, highlighting how reflection affects signal properties and demonstrating that flux intensity scales with primary energy, aiding future cosmic ray detection efforts.

Contribution

It introduces a simulation method for reflected radio signals from air showers, enabling improved energy reconstruction for balloon and satellite experiments.

Findings

Reflected radio signals' frequency spectrum depends on observer angle.

Flux intensity scales with the square of primary particle energy.

Simulation provides a foundation for future cosmic ray detection experiments.

Abstract

We present the calculation of coherent radio pulses emitted by extensive air showers induced by ultra-high energy cosmic rays accounting for reflection on the Earth's surface. Results have been obtained with a simulation program that calculates the contributions from shower particles after reflection at a surface plane. The properties of the radiation are discussed in detail emphasizing the effects of reflection. The shape of the frequency spectrum is shown to be closely related to the angle of the observer with respect to shower axis, becoming hardest in the Cherenkov direction. The intensity of the flux at a fixed observation angle is shown to scale with the square of the primary particle energy to very good accuracy indicating the coherent aspect of the emission. The simulation methods of this paper provide the foundations for energy reconstruction of experiments looking at the Earth from balloons and satellites. They can also be used in dedicated studies of existing and future experimental proposals.