Evidence of antineutrinos from distant nuclear reactors using SNO+ filled with water

SNO+ is a large, optical neutrino detector, currently filled with liquid scintillator, with a broad research program. The experiment first operated while the detector was filled with the water, between 2017 and 2019. Using that data, collected with exceptionally low backgrounds and trigger thresholds, SNO+ demonstrated the first evidence of neutrinos from distant (more than 240 km) nuclear reactors in a water Cherenkov detector. This result highlights the ability to use water Cherenkov detectors to perform monitoring of distant nuclear reactors using a well-understood, inexpensive, and easy-to-handle material.