Results of the NEMO3 experiment

Abstract

The purpose of the NEMO3 experiment is to detect neutrinoless double beta decay in order to determine the nature of neutrino and its absolute mass. We analysed the 389 effective days of data from the $\sim 7$ kg of $^{100}$Mo and $\sim 1$ kg of $^{82}$Se and obtained the following limits on the half-life for the \bb process: $T_{1/2}(\beta\beta0 \nu) > 4.6 \times 10^{23}$ years (Mo) and $T_{1/2}(\beta \beta 0 \nu) > 1.0 \times 10^{23}$ years (Se). The corresponding limits on the neutrino effective mass are $<m_{\nu}> <$ 0.7 - 2.8 eV (Mo) and $<m_{\nu}> >$ 1.7 - 4.9 eV (Se) at 90% Confident Level. We also performed a detailled analysis on the double beta decay of $^{100}$Mo into the excited states $0^+_1$, $2^+_1$ of $^{100}$Ru. The results are: $T_{1/2}(\beta \beta 2 \nu \to 0^+_1) = 5.7^{+1.3}_{-0.9}(stat)\pm 0.7 (syst) \times 10^{20}$ years, $T_{1/2}(\beta \beta 2 \nu \to 2^+_1) > 1.1 \times 10^{21}$ years, $T_{1/2}(\beta \beta 0 \nu \to 0^+_1) > 8.9 \times 10^{22}$ years, $T_{1/2}(\beta \beta 0 \nu \to 2^+_1) > 1.6 \times 10^{23}$ years.