Measurement of the 2νββ decay half-life and search for the 0νββ decay of ~(116)Cd with the NEMO-3 detector

摘要

The NEMO-3 experiment measured the half-life of the 2νββ decay and searched for the 0νββ decay of ~(116)Cd. Using 410 g of ~(116)Cd installed in the detector with an exposure of 5.26 y, (4968 ± 74) events corresponding to the 2νββ decay of ~(116)Cd to the ground state of ~(116)Sn have been observed with a signal to background ratio of about 12. The half-life of the 2νββ decay has been measured to be T_(1/2)~(2ν) =[2.74 ± 0.04(stat) ±0.18(syst)] × 10~(19) y. No events have been observed above the expected background while searching for 0νββ decay. The corresponding limit on the half-life is determined to be T_(1/2)~ (0ν) ≥ 1.0 × 10~(23) y at the 90% C.L. which corresponds to an upper limit on the effective Majorana neutrino mass of ≤ 1.4-2.5 eV depending on the nuclear matrix elements considered. Limits on other mechanisms generating 0νββ decay such as the exchange of R-parity violating supersymmetric particles, right-handed currents and majoron emission are also obtained.