Speaker
Description
Several experiments aim to detect ultra-high-energy neutrinos (UHENs) by instrumenting the upper 100 to 200 m of the polar ice sheets with radio antennas, either searching for Askaryan emission from in-ice particle cascades or illuminating the ice with radar and searching for reflections off the resulting ionization trails. These detector geometries make them sensitive to radio propagation through the firn, the layer of compacting snow in which the refractive index increases with depth and varies laterally and temporally. We show that seasonal changes in snow accumulation, temperature, and surface density, together with episodic melt events, modify the density and refractive-index structure of the upper firn, resulting in fluctuations in signal amplitude and propagation time, creating an inherent geometry dependent uncertainty for neutrino reconstruction that is irreducible when using smooth and static ice models. Accounting for the evolving firn structure is important for detection and reconstruction strategies for current and future radio-based UHEN experiments.