  The Askaryan Radio Array (ARA) experiment at the South Pole is designed to
detect high-energy neutrinos which, via in-ice interactions, produce coherent
radiation at frequencies up to 1000 MHz. In Dec. 2018, a custom high-amplitude
radio-frequency transmitter was lowered into the 1700 m SPICE ice core to
provide test sources for ARA receiver stations sensitive to vertical and
horizontal polarizations. For these tests, signal geometries correspond to
obliquely propagating radio waves from below. The ARA collaboration has
recently measured the polarization-dependent time delay variation, and report
more significant time delays for trajectories perpendicular to ice flow. Here
we use fabric data from the SPICE ice core to construct a bounding model for
the ice birefringence and the polarization time delays across ARA. The
data-model comparison is consistent with the vertical girdle fabric at the
South Pole having the prevailing horizontal crystallographic axis oriented
near-perpendicular to ice flow. This study presents the possibility that ice
birefringence can be used to constrain the range to a neutrino interaction, and
hence aid in neutrino energy reconstruction, for in-ice experiments such as
ARA.
