Search for Neutrinoless Double-Beta Decay of Te 130 with CUORE-0

We report the results of a search for neutrinoless double-beta decay in a 9.8 kg yr exposure of 130 Te using a bolometric detector array, CUORE-0. The characteristic detector energy resolution and background level in the region of interest are 5.1 ± 0.3     keV FWHM and 0.058 ± 0.004 ( stat ) ± 0.002 ( syst ) counts / ( keV   kg   yr ) , respectively. The median 90% C.L. lower-limit half-life sensitivity of the experiment is 2.9 × 10 24     yr and surpasses the sensitivity of previous searches. We find no evidence for neutrinoless double-beta decay of 130 Te and place a Bayesian lower bound on the decay half-life, T 0 ν 1 / 2 > 2.7 × 10 24     yr at 90% C.L. Combining CUORE-0 data with the 19.75 kg yr exposure of 130 Te from the Cuoricino experiment we obtain T 0 ν 1 / 2 > 4.0 × 10 24     yr at 90% C.L. (Bayesian), the most stringent limit to date on this half-life. Using a range of nuclear matrix element estimates we interpret this as a limit on the effective Majorana neutrino mass, m β β < 270 – 760    meV .