BEXCO - RoomD (108)
[NU135] Observation of two deep, distant (1.45, 4)km impulsive RF transmitters by the Askaryan Radio Array (ARA).
The Askaryan Radio Array (ARA) operates two stations (ARA-2, ARA-3) each with 16 antennas deployed on the corners of a cuboid at depths of 175-200 m at South Pole. The antennas are sensitive to either vertical (8 antennas) or horizontal (8 antennas) polarized radiation arriving from in-ice neutrino-induced cascades. At the time of IceCube construction, two calibration pulsers were deployed at a depth of 1400 m on two strings proximal to the ARA stations. These pulsers were operated during the 2014-15 and 2016-17 seasons and were detected as triggered events by ARA stations. The received signals can be used to study the complex ice permittivity at radio frequencies, including attenuation, index of refraction and birefringence. Standard ARA reconstruction of the deep pulser locations validates station geometry, and the index of refraction model used by ARA. We observe clear birefringent effects for horizontally propagating signals in polar ice. We also discuss plans to utilize the open SPIceCore hole to broadcast to existing and planned ARA stations, further characterize the South Pole ice as a function of depth, and test the paradigm of geometric optics for the propagation of electromagnetic meter wavelength radiation through polar ice.