NuDot: Double-Beta Decay with Direction Reconstruction in Liquid Scintillator

As neutrinoless double-beta decay searches seek to reach into and beyond the inverted hierarchy regime, new strategies are needed to reject background events in kiloton-scale detectors. In monolithic liquid-scintillator-based detectors, otherwise-irreducible backgrounds like ⁸B solar neutrino scattering could be identified by their event topology and novel deep-learning-based algorithms. NuDot is a 1-ton prototype that aims to demonstrate Cherenkov signal momentum reconstruction of ~1 MeV beta particles. In the FlatDot test-stand, the NuDot collaboration has demonstrated the first liquid scintillator timing-based Cherenkov/scintillation light separation of < 2 MeV beta decay events, validating NuDot's photodetectors and DAQ approach. FlatDot has also allowed for tests of novel liquid scintillator cocktails, including the use of quantum dots as wavelength shifters. The NuDot detector is currently undergoing construction and commissioning at MIT. In the coming months, we will conduct surface measurements demonstrating direction reconstruction of calibration source beta events, followed by an underground measurement of two-neutrino double-beta decay with direction reconstruction.