Flux Estimates and Detection Prospects for Lunar Geoneutrinos

TL;DR

This paper models lunar geoneutrino fluxes based on lunar interior composition, evaluates detection prospects at specific sites, and discusses potential for measuring heat-producing elements' contributions.

Contribution

It provides the first detailed calculations of lunar geoneutrino fluxes and assesses detection methods and prospects for future measurements.

Findings

Maximum lunar geoneutrino flux is slightly below Earth's KamLAND site flux.

Minimum flux is about 8.63 times lower than maximum.

Detection prospects vary across different reaction channels.

Abstract

The distribution of heat-producing elements (U, Th, K) within the Moon is critical for understanding its thermal evolution and formation history. Based on a refined lunar interior model, we calculate the geoneutrino fluxes at two representative detector locations that bracket the expected signal intensity. The maximum flux is found to be slightly lower than the corresponding predicted fluxes for the KamLAND site on Earth, while the minimum flux is approximately a factor of 8.63 lower than this maximum value. The angular distributions of geoneutrinos arriving at the two locations were further computed. Finally, we evaluate the detection prospects for lunar geoneutrinos using three reaction channels: inverse beta decay reaction, elastic scattering on electrons, and a novel radiochemical approach based on $\bar{\nu}_e + ^3$He $\to e^+ + ^3$H. For each reaction, we calculate the expected event rates and briefly discuss the potential for measuring the total geoneutrino flux, as well as the relative contributions from U, Th, and K.