Elasto-dynamical character of the nuclear matter and macroscopic models of magnetic giant resonances

A collective model is proposed to describe the magnetic giant resonances in spherical nuclei. It is based on the macroscopic equations which assume an elasto-dynamic response of the nucleon Fermi gas. The nucleus is represented by a sphere of continuous elastic matter. One supposes then that the magnetization obtained in the in the considered resonances results from torsion waves. Under special consideration are magnetic dipole resonances associated to the vibrations of the magnetic currents at the nuclear surfaces. For this perturbation the nuclear core is considered as inert. Then the collective excitation motion appears as a scissors non-radial motion of the peripheral region relative to the rotationally invariant core. The Thomas-Fermi extended method is used to provide the profiles of the mean density by means of a Skyrme force. This density is used to calculate the torsion inertial momenta and the rigidity parameters defining the collective Hamiltonian. The results of our systematic calculations for the energies and transition probabilities from the M1 giant resonances are compared with the data of nuclear fluorescence as well as with those from electron inelastic backscattering