Nuclear structure of N = 86 isotones of Ce, Nd, Sm and Gd

The collectivity in the low-energy spectra of N = 86 isotones of Ce, Nd, Sm and Gd is studied vis-a-vis their vibrational band structure. The energy level pattern and the E2 transition rates are compared with the predictions of the microscopic dynamic pairing plus quadrupole model plus 5DCH (Bohr-Mottelson view). The role of the Z = 64 subshell in the increase of ground band level energies with increasing Z, and the different effects on the B(E2) values are illustrated. The subshell energy gap versus the occupation of Nilsson single-particle orbits is discussed. A brief discussion of the different current microscopic collective models is also given. (orig.)