LUNASKA experiments using the Australia Telescope Compact Array to search for ultra-high energy neutrinos and develop technology for the lunar Cherenkov technique

TL;DR

This paper reports on experiments using the Australia Telescope Compact Array to detect ultra-high energy neutrinos via lunar Cherenkov radiation, including sensitivity analysis and technological development for future large radio arrays.

Contribution

It presents the design, performance, and results of lunar Cherenkov experiments with ATCA, and estimates the impact of surface roughness on detection capabilities, advancing the lunar UHE neutrino detection technique.

Findings

Set a limit on isotropic neutrino flux.

Surface roughness may enhance near-surface event detectability.

Developed technology for future SKA-based lunar Cherenkov experiments.

Abstract

We describe the design, performance, sensitivity and results of our recent experiments using the Australia Telescope Compact Array (ATCA) for lunar Cherenkov observations with a very wide (600 MHz) bandwidth and nanosecond timing, including a limit on an isotropic neutrino flux. We also make a first estimate of the effects of small-scale surface roughness on the effective experimental aperture, finding that contrary to expectations, such roughness will act to increase the detectability of near-surface events over the neutrino energy-range at which our experiment is most sensitive (though distortions to the time-domain pulse profile may make identification more difficult). The aim of our "Lunar UHE Neutrino Astrophysics using the Square Kilometer Array" (LUNASKA) project is to develop the lunar Cherenkov technique of using terrestrial radio telescope arrays for ultra-high energy (UHE) cosmic ray (CR) and neutrino detection, and in particular to prepare for using the Square Kilometer Array (SKA) and its path-finders such as the Australian SKA Pathfinder (ASKAP) and the Low Frequency Array (LOFAR) for lunar Cherenkov experiments.