Sensitivity of a low threshold directional detector to CNO-cycle solar neutrinos

TL;DR

This paper explores the potential of a water-based liquid scintillator detector with directional sensitivity to measure CNO-cycle solar neutrinos, which could resolve the solar metallicity problem and improve neutrino flux measurements.

Contribution

It demonstrates the feasibility and necessary conditions for a low-threshold, directional detector to detect CNO neutrinos and measure pep neutrinos with high precision.

Findings

Detector sensitivity depends on background levels and detector design.

Directional detection significantly enhances neutrino signal discrimination.

A well-designed detector can measure CNO neutrino flux and pep neutrinos with high accuracy.

Abstract

A first measurement of neutrinos from the CNO fusion cycle in the Sun would allow a resolution to the current solar metallicity problem. Detection of these low-energy neutrinos requires a low-threshold detector, while discrimination from radioactive backgrounds in the region of interest is significantly enhanced via directional sensitivity. This combination can be achieved in a water-based liquid scintillator target, which offers enhanced energy resolution beyond a standard water Cherenkov detector. We study the sensitivity of such a detector to CNO neutrinos under various detector and background scenarios, and draw conclusions about the requirements for such a detector to successfully measure the CNO neutrino flux. A detector designed to measure CNO neutrinos could also achieve a few-percent measurement of pep neutrinos.