Measurement of the double-β decay half-life of Nd150 and search for neutrinoless decay modes with the NEMO-3 detector

The half-life for double-β decay of Nd150 has been measured by the NEMO-3 experiment at the Modane Underground Laboratory. Using 924.7 days of data recorded with 36.55 g of Nd150, we measured the half-life for 2νββ decay to be T1/22ν=(9.11-0.22+0.25(stat.)±0.63(syst.))×1018 yr. The observed limit on the half-life for neutrinoless double-β decay is found to be T1/20ν1.8×1022 yr at 90% confidence level. This translates into a limit on the effective Majorana neutrino mass of mν<4.0-6.3 eV if the nuclear deformation is taken into account. We also set limits on models involving Majoron emission, right-handed currents, and transitions to excited states. © 2009 The American Physical Society.