Various nuclear structures in Xe140 studied by β decay of ground and isomeric states in I140

Abstract

Structure of the neutron-rich N = 86 isotope 140 Xe, located northeast of a doubly-magic nucleus 132 Sn, is investigated by β-γ spectroscopy. Two β-decay isomers in 140 I are newly found in the study of two different β decays of 140 I which were produced by two reactions (i) direct in-flight fission at a primary target and (ii) β decay of 140 Te at an active stopper. Half-lives of the β decays of the ground state, the low-spin isomer, and the high-spin isomer are determined to be 0.38(2), 0.91(5), and 0.47(4) s, respectively. Decay schemes of the β decay of the high-spin isomer and of the mixed β decays of the ground state and the low-spin isomer in 140 I to 140 Xe are constructed using the information on γ -ray coincidence relation and γ -ray intensity. Nuclear structures of the low-lying states in 140 Xe and 140 I are discussed by comparing the experimental results to two theoretical calculations based on a large-scale shell model and the deformed Skyrme Hartree-Fock-Bogoliubov plus deformed quasiparticle-random-phase approximation. Possible candidates for (quasi-)γ -band members of *