Shell-model study of two-neutrino double-beta decay for Z=40 50 nuclei and their SSD properties


 In this paper, large-scheme shell-model calculations are carried out for two-neutrino double-beta decay of Z=40–50 nuclei (94Zr, 96Zr, 98Mo, 104Ru, 108Cd, and 116Cd). Within this region, only the half-lives of nuclei 96Zr and 116Cd are experimentally known. The calculated results agree well with experimental data and we predict the half-lives for the remaining four nuclei. Among them, 94Zr and 104Ru have relatively short half-lives of 4.57×1023 and 9.83×1023 years, respectively, together with large abundance, and are expected to be detected in the near future. By analyzing the convergence of nuclear matrix elements, special attention is paid to their single-state dominance (SSD) property. Here, a new SSD nucleus, i.e., 94Zr, is found, which is a supplement to the previous SSD nuclei list. keyword:two-neutrino double-beta decay, half-life, single-state dominance (SSD) property