Why is the universe dominated by matter, and not antimatter? Neutrinos, with their changing flavors and tiny masses, could provide an answer. If the neutrino is a Majorana particle, meaning that it is its own antiparticle, it would reveal the origin of the neutrino’s mass, demonstrate that lepton number is not a conserved symmetry of nature, and provide a path to leptogenesis in the early universe. To discover whether this is the case, we must search for neutrinoless double-beta decay, a theorized process that would occur in some nuclei. By searching for this extremely rare decay, we can explore new physics at energy scales that only existed in the seconds following the Big Bang.

Detecting this extremely rare process, however, requires us to build very large detectors with very low background rates. Experiments using germanium detectors, like the Majorana Demonstrator, which is currently running, and LEGEND-200, which is moving forward quickly, are a promising strategy to explore lifetimes of up to 10^{28} years. The current generation of experiments have achieved the lowest backgrounds of any technique, and have a clear path forward to move to the ton-scale. I’ll present recent results from the Demonstrator, an update on LEGEND-200’s progress, and prospects for LEGEND-1000.

Reaching lifetimes beyond 10^{28} years, however, will require new techniques and kiloton-scale detectors. NuDot is a proof-of-concept liquid scintillator experiment that will explore new techniques for isotope loading and background rejection in future detectors. I’ll discuss the progress we’ve already made in demonstrating how previously-ignored Cherenkov light signals can help us distinguish signal from background, and the technologies we’re developing with an eye towards the coming generations of experiments.