Boson expansion description of collective states in Ru and Pd isotopes

We have applied the boson expansion method to describe the low-lying positive parity states of even-even Ru and Pd isotopes. Energy levels, $B\left(E2\mathrm{}\right)\text{'}\mathrm{s}$, branching ratios, and magnetic dipole and electric quadrupole moments have been calculated and are in good agreement with experiment. It is particularly emphasized that our theory describes rather well the properties of the three-phonon-like $3_1^{+}$ state.