Design and Initial Performance of the Askaryan Radio Array Prototype EeV Neutrino Detector at the South Pole

TL;DR

The paper reports on the design, initial deployment, and performance evaluation of the Askaryan Radio Array prototype at the South Pole, demonstrating its potential for ultra-high energy neutrino detection in ice.

Contribution

It presents the first operational results of the ARA prototype, including background noise analysis, ice radio clarity, and successful detection of signals over large distances, confirming the array's sensitivity.

Findings

Background noise dominated by thermal and galactic noise.

Successful detection of signals from 2.5 km deep impulse generator over 3 km.

Prototype results support the high sensitivity of the planned ARA-37 array.

Abstract

We report on studies of the viability and sensitivity of the Askaryan Radio Array (ARA), a new initiative to develop a Teraton-scale ultra-high energy neutrino detector in deep, radio-transparent ice near Amundsen-Scott station at the South Pole. An initial prototype ARA detector system was installed in January 2011, and has been operating continuously since then. We report on studies of the background radio noise levels, the radio clarity of the ice, and the estimated sensitivity of the planned ARA array given these results, based on the first five months of operation. Anthropogenic radio interference in the vicinity of the South Pole currently leads to a few-percent loss of data, but no overall effect on the background noise levels, which are dominated by the thermal noise floor of the cold polar ice, and galactic noise at lower frequencies. We have also successfully detected signals originating from a 2.5 km deep impulse generator at a distance of over 3 km from our prototype detector, confirming prior estimates of kilometer-scale attenuation lengths for cold polar ice. These are also the first such measurements for propagation over such large slant distances in ice. Based on these data, ARA-37, the 200 km^2 array now under construction, will achieve the highest sensitivity of any planned or existing neutrino detector in the 10^{16}-10^{19} eV energy range.