Modeling Biaxial Birefringence of Antarctic Ice With Data From the Askaryan Radio Array

Detecting Ultra-High Energy (UHE) neutrinos requires instrumenting vast volumes of transparent media to observe their rare interactions and low flux. The Askaryan Radio Array (ARA) is designed to detect UHE neutrinos using the radio Askaryan technique in Antarctic ice at the south pole. South pole ice may act as a biaxially birefringent medium on radio signals. In biaxially birefringent media, radio signals propagate as two rays with different speeds, and the polarization of these rays can rotate as they travel through the medium. These two effects depend on the propagation direction and polarization of the signal. Understanding these effects can improve the reconstruction of both the initial polarization and incoming neutrino energy. We use data from the South Pole Ice Core Experiment (SPICE) to look for effects of biaxial birefringence on reconstructed polarizations at varying depths, as seen by five ARA stations. Here, I will discuss efforts to fit a model of birefringence to the SPICE data.