Double-β decay of 82Se

Abstract The NEMO-2 tracking detector located in the Frejus Underground Laboratory was designed as a prototype of the NEMO-3 detector to study neutrinoless (Oν) and two neutrino (2ν) double-beta decay (ββ) physics. After 10357 h of running with an isotopically enriched selenium source (2.17 mol yr of 82 Se) a ββ2ν decay half-life of T 1 2 = (0.83 ± 0.10( stat ) ± 0.07 ( syst )) × 10 20 yr was measured. Limits with a 90% C.L. on the 82 Se half-lives of 9.5 × 10 21 yr for ββ0ν decay to the ground state, 2.8 × 10 21 yr to the (2 + ) excited state and 2.4 × 10 21 yr for ββ 0 νχ 0 decay with a Majoron ( χ 0 ) were also obtained.