Latest results from NEMO-3 and status of SuperNEMO

Abstract

The NEMO-3 experiment performed precise measurement of the double beta decay and searched for the neutrinoless double beta decay on seven isotopes, among which 100Mo and 82Se were the dominant ones. The detector, installed in the Laboratoire Souterrain de Modane, took data for 8 years before being decommissioned in 2011. The key feature of NEMO-3 was its unique capability to fully reconstruct the kinematics of the events, which allowed to reduce the backgrounds and to discriminate among different mechanisms beyond the neutrino-less double beta decay. No evidence of 0νββ events has been found with an exposure of 34.7 kg×y of 100Mo, providing a limit for the light Majorana neutrino mass mechanism of T1/20νββ>1.1×1024 y (90 % C.L.) which corresponds to an effective neutrino mass of |mββ|<0.3−0.9 eV, depending from the Nuclear Matrix Element considered. Furthermore, no background events in the double electron channel has been found in the energy region 3.2 – 10 MeV after an exposure of 47 kg×y. The same experimental technique has been adopted for the next generation experiment called SuperNEMO. The new detector has a modular design with the capability to measure different isotopes at the same time, 48Ca, 82Se and 150Nd are currently under consideration. With 20 detection modules observing for 5 years 100 kg of 82Se, the expected sensitivity should reach T1/20ν>1026 y (|mββ|<0.04 – 0.10 eV) competitive with others experiments. In order to demonstrate the feasibility of the full experiment, the first step is the imminent construction of a first demonstrator module containing 7 kg of 82Se. With an expected sensitivity of T1/20ν>6.6×1024 y (|mββ|<0.2 – 0.4 eV) after 2.5 y, the demonstrator module will also be able to perform a competitive measurement.