With long experience using germanium detectors for fundamental physics research, he has worked on GRETINA/GRETA and the Majorana Demonstrator. He is now the U.S-DOE Project Director of the Large Enriched Germanium Experiment for Neutrinoless ββ Decay (LEGEND-1000). LEGEND-1000 is a search for a hypothesized very rare decay of atomic nuclei, called neutrinoless double-beta decay. If seen, this decay would prove that the neutrino and anti-neutrino are the same particle and that Lepton Number is not conserved. It could help solve the long-standing question of how the Big Bang produced the universe with an excess of matter over antimatter.