In-ice Radio Signatures of Cosmic Ray Particle Cascades

Abstract: To detect ultra-high-energy neutrinos, experiments such as the Askaryan Radio Array and the Radio Neutrino Observatory in Greenland target the radio emission induced by these particles as they cascade in the ice, using deep in-ice antennas at the South Pole or in Greenland. A crucial step toward this goal is the characterization of the in-ice radio emission from cosmic-ray-induced particle showers. These showers form a primary background for neutrino searches, but can also be used to validate the detection principle and provide calibration signals for in-ice radio detectors. In this work, we use the Monte-Carlo framework FAERIE to perform the first characterization of cosmic ray signals with simulations that incorporate both their in-air and in-ice emissions. We investigate cosmic ray signatures such as their radiation energy, timing, polarization and frequency spectrum and quantify how they depend on shower properties. These results provide key guidelines for cosmic-ray identification and cosmic-ray neutrino discrimination in future in-ice radio experiments.