The interacting boson approximation (IBA) is employed in the present article to follow the structural evolution of the neutron-deficient nuclei from the $Z=52–62$ region. The IBA model parameters are determined to reproduce the properties of the low-lying positive parity excitations for a wide range of even-even collective nuclei. The parameters aim to describe simultaneously the existing electromagnetic data (energy levels, transition matrix elements, etc.) and hadronic ones (two-nucleon transfer intensities). It is shown that a simple Hamiltonian with only two terms is not adequate to describe the properties across this region. It is found that the octupole term plays an important role in reproducing the properties of the $2_{\gamma }^{+}$ and $0_2^{+}$ states, as well as in the description of the two-neutron transfer intensities patterns. A mapping of these parameters in the IBA symmetry triangle allows the comparison of representative trajectories for different isotopic chains.

• Received 30 March 2010

DOI:https://doi.org/10.1103/PhysRevC.81.054321