Radio-Frequency Measurements of Coherent Transition and Cherenkov Radiation: Implications for High-Energy Neutrino Detection

TL;DR

This study measures radio emissions from electron interactions to understand signals from high-energy neutrino detection, revealing coherent radiation phenomena relevant for astrophysical neutrino experiments.

Contribution

It provides experimental data on radio emissions from electron interactions, informing the design of neutrino detection experiments relying on coherent radio signals.

Findings

Detected coherent radio emission consistent with transition and Cherenkov radiation.

Emission levels vary with experimental setup, affecting neutrino detection strategies.

Implications for optimizing radio-based high-energy neutrino observatories.

Abstract

We report on measurements of 11-18 cm wavelength radio emission from interactions of 15.2 MeV pulsed electron bunches at the Argonne Wakefield Accelerator. The electrons were observed both in a configuration where they produced primarily transition radiation from an aluminum foil, and in a configuration designed for the electrons to produce Cherenkov radiation in a silica sand target. Our aim was to emulate the large electron excess expected to develop during an electromagnetic cascade initiated by an ultra high-energy particle. Such charge asymmetries are predicted to produce strong coherent radio pulses, which are the basis for several experiments to detect high-energy neutrinos from the showers they induce in Antarctic ice and in the lunar regolith. We detected coherent emission which we attribute both to transition and possibly Cherenkov radiation at different levels depending on the experimental conditions. We discuss implications for experiments relying on radio emission for detection of electromagnetic cascades produced by ultra high-energy neutrinos.