Quadrupole and hexadecapole deformations in the actinide nuclei

Model-dependent deformation parameters, β20 and β40, are extracted from measured E2 and E4 transition moments for a distribution of nuclear charge represented by a three-parameter deformed Fermi distribution with a parabolic center depression. For the thorium and uranium nuclei this shape of the charge distribution reduces the extracted values of β20 by 5--10 % and β40 by 10--15 % from the values obtained with a two-parameter deformed Fermi distribution