Final Result of the MAJORANA DEMONSTRATOR?s Search for Neutrinoless Double-? Decay in ⁷⁶Ge

The MAJORANA DEMONSTRATOR searched for neutrinoless double-beta decay (0 nu beta beta) of 76Ge using modular arrays of high-purity Ge detectors operated in vacuum cryostats in a low-background shield. The arrays operated with up to 40.4 kg of detectors (27.2 kg enriched to similar to 88% in 76Ge). From these measurements, the DEMONSTRATOR has accumulated 64.5 kg yr of enriched active exposure. With a world-leading energy resolution of 2.52 keV FWHM at the 2039 keV Q beta beta (0.12%), we set a half-life limit of 0 nu beta beta in 76Ge at T1/2 > 8.3 x 1025 yr (90% C.L.). This provides a range of upper limits on m beta beta of (113-269) meV (90% C.L.), depending on the choice of nuclear matrix elements.