M1 strengths in deformed nuclei

The Elliott SU(3) model, extended via pseudo-spin for heavy nuclei, is used to study low-lying magnetic dipole excitations in deformed nuclei. Proton and neutron degrees of freedom are handled explicitly and the system Hamilt onian includes single-particle energies as well as quadrupole-quadrupole an d pairing two-body interactions, The calculated excitation spectra and M1 s trength distribution of the strongly deformed even-even Gd156-160 isotopes are shown to be in good agreement with experimental results. Results for th e gamma-unstable (soft rotor) Pt-196 nucleus and the even-odd Dy-163 system are also reported and found to compare favourably with the available exper imental data, demonstrating the ability of the model to describe very diffe rent types of systems.