New isomers in 125 Pd 79 and 127 Pd 81 : Competing proton and neutron excitations in neutron-rich palladium nuclides towards the N=82 shell closure

Abstract

The neutron-rich isotopes of palladium have attracted considerable interest in terms of the evolution of the neutron shell closure and its influence on the r-process nucleosynthesis. In this Letter, we present the first spectroscopic information on the excited states in 125Pd79 and 127Pd81 studied using the EURICA γ-ray spectrometer, following production via in-flight fission of a high-intensity 238U beam at the RIBF facility. New isomeric states with half-lives of 144(4) ns and 39(6) μs have been assigned spins and parities of () and () in 125Pd and 127Pd, respectively. The observed level properties are compared to a shell-model calculation, suggesting the competition between proton excitations and neutron excitations in the proton-hole and neutron-hole systems in the vicinity of the doubly magic nucleus 132Sn. Show more