beta-delayed gamma-ray spectroscopy of non-yrast states in Te-138 near the neutron drip line

We report on the first beta-decay data of Sb-138 to Te-138 isotopes beyond the doubly magic Sn-132. The parent nucleus was produced by the in-flight fission of a U-238 beam on a Be-9 target at 345 MeV per nucleon and measured at the BigRIPS separator of the Radioactive Isotope Beam Factory at RIKEN. By using advanced beta-gamma spectroscopy techniques, the half-life and the tentative spin-parity of Sb-138 were measured to be 346(19) ms and (3(-)), respectively. In addition, we observed several low-lying non-yrast states in Te-138 for the first time. Our data allowed us to rearrange the positions of the first 2(+) and 4(+) states in this nucleus and to construct the level scheme of Te-138 in accordance with shell-model calculations. Additionally, we extend energy systematics of Te isotopes within neutron numbers 54 and 86.