MeV-scale performance of water-based and pure liquid scintillator detectors

TL;DR

This study evaluates the performance of water-based and pure liquid scintillator detectors at MeV energies, focusing on resolution, particle identification, and physics sensitivities for neutrino and Majorana neutrino searches.

Contribution

It provides a comprehensive comparison of water-based and pure scintillator detectors, including modifications of scintillation timing, with implications for neutrino physics and detector design.

Findings

50-kt detector can measure CNO neutrino flux with better than 10% precision in 5 years.

1-kt detector can achieve better than 5% detection efficiency for neutrinos.

Liquid scintillator model shows sensitivity to Majorana neutrinos with half-life >1.4×10^{28} years.

Abstract

This paper presents studies of the performance of water-based liquid scintillator in both 1-kt and 50-kt detectors. Performance is evaluated in comparison to both pure water Cherenkov detectors and a nominal model for pure scintillator detectors. Performance metrics include energy, vertex, and angular resolution, along with a metric for ability to separate the Cherenkov from the scintillation signal, as being representative of various particle identification capabilities that depend on the Cherenkov / scintillation ratio. We also modify the time profile of scintillation light to study the same performance metrics as a function of rise and decay time. We go on to interpret these results in terms of their impact on certain physics goals, such as solar neutrinos and the search for Majorana neutrinos. This work supports and validates previous results, and the assumptions made therein, by using a more complete detector model and full reconstruction. We confirm that a high-coverage, 50-kt detector would be capable of better than 10 (1)\% precision on the CNO neutrino flux with a WbLS (pure LS) target in 5 years of data taking. A 1-kt LS detector, with a conservative 50\% fiducial volume of 500~t, can achieve a better than 5\% detection. Using the liquid scintillator model, we find a sensitivity into the normal hierarchy region for Majorana neutrinos, with half life sensitivity of $T^{0\nu\beta\beta}_{1/2} > 1.4 \times 10^{28}$ years at 90\% CL for 10 years of data taking with a Te-loaded target.