On the structure of two-quasiparticle states in even-A Xe isotopes
The excitation energies of proton and neutron two-quasiparticle states in even-A xenon isotopes are studied within the shell-model framework. The results suggest that in the lighter isotopes (A≦126) the proton excitations might be yrast, whereas in the heavier ones (A≧130) the neutron-hole excitations dominate at lower energies. This finding would then explain the complex excitation spectra found in126, 128, 130Xe, where the two excitation modes occur at comparable energies.