The β decays of 102Sn and 104Sn were studied by using high-resolution germanium detectors as well as a Total Absorption Spectrometer (TAS). For 104Sn, with three new β-delayed γ-rays identified, the total Gamow-Teller strength (BGT) value of 2.7(3) was obtained. For 102Sn, the γ-γ coincidence data were collected for the first time, allowing us to considerably extend the decay scheme. This scheme was used to unfold the TAS data and to deduce a BGT value of 4.2(8) for this decay. This result is compared to shell model predictions, yielding a hindrance factor of 3.6(7) in agreement with those obtained previously for 98Cd and 100In. Together with the latter two, 102Sn completes the triplet of Z ⩽ 50, N ≥ 50 nuclei with two proton holes, one proton hole and one neutron particle, and two neutron particles with respect to the doubly magic 100Sn core.
21.10.-k Properties of nuclei; nuclear energy levels23.40.-s Beta decay; double β decay; electron and muon capture23.20.Lv Gamma transitions and level energies27.60.+j 90≤A≤149