Alternative design for large scale liquid scintillator detectors
Physical Review D American Physical Society (APS) 105:7 (2022) 072003
Optical calibration of the SNO+ detector in the water phase with deployed sources
Journal of Instrumentation IOP Publishing 16 (2021) P10021
Abstract:
SNO+ is a large-scale liquid scintillator experiment with the primary goal of searching for neutrinoless double beta decay, and is located approximately 2 km underground in SNOLAB, Sudbury, Canada. The detector acquired data for two years as a pure water Cherenkov detector, starting in May 2017. During this period, the optical properties of the detector were measured in situ using a deployed light diffusing sphere, with the goal of improving the detector model and the energy response systematic uncertainties. The measured parameters included the water attenuation coefficients, effective attenuation coefficients for the acrylic vessel, and the angular response of the photomultiplier tubes and their surrounding light concentrators, all across different wavelengths. The calibrated detector model was validated using a deployed tagged gamma source, which showed a 0.6% variation in energy scale across the primary target volume.The SNO+ experiment
Journal of Instrumentation IOP Publishing 16:8 (2021) P08059
Abstract:
The SNO+ experiment is located 2 km underground at SNOLAB in Sudbury, Canada. A low background search for neutrinoless double beta (0νββ) decay will be conducted using 780 tonnes of liquid scintillator loaded with 3.9 tonnes of natural tellurium, corresponding to 1.3 tonnes of 130Te. This paper provides a general overview of the SNO+ experiment, including detector design, construction of process plants, commissioning efforts, electronics upgrades, data acquisition systems, and calibration techniques. The SNO+ collaboration is reusing the acrylic vessel, PMT array, and electronics of the SNO detector, having made a number of experimental upgrades and essential adaptations for use with the liquid scintillator. With low backgrounds and a low energy threshold, the SNO+ collaboration will also pursue a rich physics program beyond the search for 0νββ decay, including studies of geo- and reactor antineutrinos, supernova and solar neutrinos, and exotic physics such as the search for invisible nucleon decay. The SNO+ approach to the search for 0νββ decay is scalable: a future phase with high 130Te-loading is envisioned to probe an effective Majorana mass in the inverted mass ordering region.Combined constraints on Majorana masses from neutrinoless double beta decay experiments
Physical Review D American Physical Society 104:1 (2021) 12002
Abstract:
Combined bounds on the Majorana neutrino mass for light and heavy neutrino exchange mechanisms are derived from current neutrinoless double beta decay (0νββ) search results for a variety of nuclear matrix element (NME) models. The approach requires self-consistency of a given model to predict NMEs across different isotopes. The derived bounds are notably stronger than those from any single experiment and show less model-to-model variation, highlighting the advantages of using multiple isotopes in such searches. Projections indicate that the combination of near-term experiments should be able to probe well into the inverted neutrino mass hierarchy region. A method to visually represent 0νββ experimental results is also suggested to more transparently compare across different isotopes and explicitly track model dependencies.Development, characterisation, and deployment of the SNO+ liquid scintillator
Journal of Instrumentation IOP Publishing 16 (2021) P05009