The sensitivity of the next generation of lunar Cherenkov observations to UHE neutrinos and cosmic rays

TL;DR

This paper simulates lunar Cherenkov detection of ultra-high energy cosmic rays and neutrinos, showing future radio telescopes could significantly improve detection sensitivity and enable detailed cosmic ray source studies.

Contribution

It expands previous models to include sub-regolith interactions and evaluates the sensitivity of upcoming radio telescopes for UHE particle detection.

Findings

Future telescopes like ASKAP and SKA can detect GZK neutrinos.

SKA low-frequency array could detect cosmic rays above 56 EeV at high rates.

Current surface uncertainties limit high-frequency sensitivity calculations.

Abstract

We present simulation results for the detection of ultra-high energy (UHE) cosmic ray (CR) and neutrino interactions in the Moon by radio-telescopes. We simulate the expected radio signal at Earth from such interactions, expanding on previous work to include interactions in the sub-regolith layer for single dish and multiple telescope systems. For previous experiments at Parkes, Goldstone, and Kalyazin we recalculate the sensitivity to an isotropic flux of UHE neutrinos. Our predicted sensitivity for future experiments using the Australia Telescope Compact Array (ATCA) and the Australian SKA Pathfinder (ASKAP) indicate these instruments will be able to detect the more optimistic UHE neutrino flux predictions, while the Square Kilometre Array (SKA) will also be sensitive to all bar one prediction of a diffuse `cosmogenic', or `GZK', neutrino flux. Current uncertainties concerning the structure and roughness of the lunar surface prevents an accurate calculation of the sensitivity of the lunar Cherenkov technique for UHE cosmic ray astronomy at high frequencies. However, below 200 MHz we find that the proposed SKA low-frequency aperture array should be able to detect events above 56 EeV at a rate about 30 times that of the current Pierre Auger Observatory. This would allow directional analysis of UHE cosmic rays, and investigation of correlations with putative cosmic ray source populations, to be conducted with very high statistics.