Speaker
Description
The Askaryan Radio Array (ARA) is a neutrino detector located at the South Pole that searches for radio emission from ultra high energy neutrino interactions within Antarctic ice. While ARA is primarily a neutrino detector, it is also sensitive to Askaryan emission from cosmic ray air showers that develop at the surface of the ice. ARA consists of five autonomous stations, each with vertical and horizontal antennas deployed up to 200 m in the ice.
Here, we present the first experimental evidence of Askaryan emission detected in naturally-occurring ice from cosmic ray events, after a re-analysis of data taken with the fifth ARA station during the 2019 season. The signal shape, arrival direction, electric field polarization, and event rate are consistent with what we would expect from theoretical predictions and inconsistent with the combined background estimate at a level of 5.1 sigma. The brightest events are additionally consistent with an extended cascade-like emission pattern.