Description of the nuclear octupole and quadrupole deformation
  A parametrization of octupole plus quadrupole deformation, in terms of intrinsic variables defined in the rest frame of the overall tensor of inertia, is presented and discussed. The model is valid for situations close to the axial symmetry, but non axial deformation parameters are not frozen to zero. The properties of the octupole excitations in the deformed Thorium isotopes Th-226, Th-228 are interpreted in the frame of this model. A tentative interpretation of octupole oscillations in nuclei close to the X(5) symmetry, in terms of an exactly separable potential, is also discussed. 
P. G. Bizzeti and A. M. Bizzeti-Sona