Nuclear structure and beta-decay schemes for Te nuclides beyond N=82

Abstract

We study for the first time the internal structure of Te-140 through the beta-delayed gamma-ray spectroscopy of Sb-140. The very neutron-rich Sb-140 nuclei with Z = 51 and N = 89 were produced by the in-flight fission of U-238 beams at the Radioactive Isotope Beam Factory, RIKEN. The half-life and spin-parity of Sb-140 are reported as 173 +/- 12 ms and 3(-), respectively. In addition to the excited states of Te-140 produced by the beta-decay branch, the beta-delayed one-neutron and two-neutron emission branches were also established. By identifying the first 2(+) and 4(+) excited states of Te-140, we found that Te isotopes persist in their vibrator character with E(4(+))/E(2(+)) = 2. We discuss the distinctive features manifest in this region revealed in pairs of isotopes with the same neutron holes and particles with respect to N = 82.