Collective vibrational bands built on two-quasiparticle excitations in Te isotopes

Abstract

The existence and importance of collective vibrational quadrupole bands on top of two-particle excitations in spherical even-even nuclei is investigated on the example of Te isotopes. Three types of structures are suggested in the framework of the quasiparticle-phonon model and are compared to experimental data systematized from the literature and confirmed by recent experiments. It is suggested that complex structures of the type $[2\mathrm{QP}\ensuremath{\bigotimes}n$ phonons] play an important role in the structure of the ${8}^{+}$ and ${10}^{+}$ states below 4.5 MeV in the Te isotopes.