Near-Field Effects of Cherenkov Radiation Induced by Ultra High Energy Cosmic Neutrinos

TL;DR

This paper investigates the near-field Cherenkov radiation from ultra-high energy cosmic neutrinos using FDTD simulations, revealing distinct near-field behaviors that can aid in neutrino detection and flavor identification.

Contribution

It introduces a numerical approach to analyze near-field Cherenkov radiation, highlighting differences from far-field approximations and potential applications in neutrino detection.

Findings

Near-field radiation differs significantly from far-field patterns.

Near-field signatures can help identify ultra-high energy electromagnetic showers.

Potential for improved neutrino flavor discrimination in ground detectors.

Abstract

The radio approach for detecting the ultra-high energy cosmic neutrinos has become a mature field. The Cherenkov pulse in radio detection originates from the charge excess of particle showers due to Askaryan effect. The conventional way of calculating the Cherenkov pulse by making far- field approximation fails when the size of elongated showers become comparable with detection distance. We investigate the Cherenkov pulse in near-field by a numerical code based on the finite- difference time-domain (FDTD) method. Our study shows that the near-field radiation exhibits very different behaviors from the far-field one and therefore can be easily recognized. For ground array neutrino detectors, the near-field radiation would provide a unique signature for ultra high energy electromagnetic showers induced by the electron neutrino charge-current interaction. This can be useful in neutrino flavor identification.