Solar neutrino detection in a large volume double-phase liquid argon experiment

TL;DR

This paper explores the potential of large-volume two-phase liquid argon detectors, originally designed for dark matter searches, to perform precision measurements of solar neutrino fluxes through neutrino-electron scattering, highlighting their low background and high resolution.

Contribution

It demonstrates, through modeling, that a 300 tonne liquid argon TPC can accurately measure solar neutrino fluxes, especially CNO, 7Be, and pep neutrinos, improving upon current results.

Findings

Potential to measure CNO neutrino rate with ~15% precision.

Significantly improved precision for 7Be and pep neutrino rates.

Background modeling supports feasibility of solar neutrino detection in LAr TPCs.

Abstract

Precision measurements of solar neutrinos emitted by specific nuclear reaction chains in the Sun are of great interest for developing an improved understanding of star formation and evolution. Given the expected neutrino fluxes and known detection reactions, such measurements require detectors capable of collecting neutrino-electron scattering data in exposures on the order of 1 ktonne yr, with good energy resolution and extremely low background. Two-phase liquid argon time projection chambers (LAr TPCs) are under development for direct Dark Matter WIMP searches, which possess very large sensitive mass, high scintillation light yield, good energy resolution, and good spatial resolution in all three cartesian directions. While enabling Dark Matter searches with sensitivity extending to the "neutrino floor" (given by the rate of nuclear recoil events from solar neutrino coherent scattering), such detectors could also enable precision measurements of solar neutrino fluxes using the neutrino-electron elastic scattering events. Modeling results are presented for the cosmogenic and radiogenic backgrounds affecting solar neutrino detection in a 300 tonne (100 tonne fiducial) LAr TPC operating at LNGS depth (3,800 meters of water equivalent). The results show that such a detector could measure the CNO neutrino rate with ~15% precision, and significantly improve the precision of the 7Be and pep neutrino rates compared to the currently available results from the Borexino organic liquid scintillator detector.