Interpretation of theA≈100transitional region in the framework of the interacting boson model

A detailed study of the transition between the SU(5) and O(6) limit of the interacting boson model (IBA-1) has been performed in a schematic way. A comparison of the experimental excitation energies and $E2$ transition probabilities for neutron-rich Ru and Pd isotopes with this calculation shows that this mass region is well described in terms of this phase transition.