Systematic investigation of the low-lying dipole excitations in even-even Ba124-136 isotopes

Abstract

Magnetic and electric dipole excitations in the energy interval 2.0-4.0MeV are studied for the even-even Ba124-136 isotopes within the rotational, translational and Galilean invariant Quasiparticle Random Phase Approximation (QRPA). The calculations show that low-lying magnetic and electric dipole states have mainly Delta K = 1 character. Systematical analysis of the summed excitation strengths of the scissors mode as a function of deformation parameters or the mass number A was also done. It is shown that in the even-even Ba124-136 isotopes, the dependence of the total B(M1) transition on delta(2)(2) is nearly linear for the well-deformed isotopes. The agreement between the calculated excitation energies as well as the summed B(M1) values of the scissors mode and the available experimental data is quite good. In addition, we predicted E1 dipole excitations for the even-even Ba124-136 isotopes which have not been observed experimentally, yet.