Simulation of in-ice cosmic ray air shower induced particle cascades

TL;DR

This paper uses detailed simulations to analyze high-energy cosmic-ray air showers in polar ice, focusing on particle cascades and their radio emissions, with implications for neutrino detection techniques.

Contribution

It introduces a combined CORSIKA and Geant4 simulation approach to model in-ice particle cascades and their Askaryan radio emissions, providing new parameterizations for analytical calculations.

Findings

The particle cascade in ice is dominated by the shower core.

The Askaryan radio emission is primarily from the shower core.

Feasibility of radar detection of plasma in ice is discussed.

Abstract

We present detailed microscopic simulations of high-energy cosmic-ray air showers penetrating high-altitude ice layers that can be found at the polar regions. We use a combination of the CORSIKA Monte Carlo code and the Geant4 simulation toolkit, and focus on the particle cascade that develops in the ice to describe its most prominent features. We discuss the impact of the ice layer on the total number of particles in function of depth of the air shower, and we give a general parameterization of the charge distribution in the cascade front in function of Xmax of the cosmic ray air shower, which can be used for analytical and semi-analytical calculations of the expected Askaryan radio emission of the in-ice particle cascade. We show that the core of the cosmic ray air shower dominates during the propagation in ice, therefore creating an in-ice particle cascade strongly resembling a neutrino-induced particle cascade. Finally, we present the results of microscopic simulations of the Askaryan radio emission of the in-ice particle cascade, showing that the emission is dominated by the shower core, and discuss the feasibility of detecting the plasma created by the particle cascade in the ice using RADAR echo techniques.