Measurement of theββDecay Half-Life ofTe130with the NEMO-3 Detector

We report results from the NEMO-3 experiment based on an exposure of 1275 days with 661 g of ${}^{130}\mathrm{Te}$ in the form of enriched and natural tellurium foils. The $\beta \beta$ decay rate of ${}^{130}\mathrm{Te}$ is found to be greater than zero with a significance of 7.7 standard deviations and the half-life is measured to be $T_{1/2}^{2\nu }=[7.0\pm 0.9(\mathrm{stat})\pm 1.1(\mathrm{syst})]\times {10}^{20}\mathrm{yr}$. This represents the most precise measurement of this half-life yet published and the first real-time observation of this decay.