Structure properties of even-even actinides at normal and super deformed shapes analysed using the Gogny force

Mean field and beyond mean field methods implemented with the DIS force are used in large scale calculations to study the structure properties of fifty five even-even actinides at normal and isomeric potential deformations. The mass region covered is spanned by the Th226-236, U228-242, Pu232-246, Cm238-250, Cf238-256, Fm242-258 and No250-262 nuclides. Hartree-Fock-Bogolyubov (HFB) calculations performed with constraints placed on axial and triaxial quadrupole deformations as well as octupole deformations serve to build tensors of inertia and potential energy landscapes up to very large elongations. Long lived spin isomers are investigated through blocking calculations performed with and without breaking time reversal symmetry. Configuration mixing calculations are performed to make predictions for shape isomers and pi = + vibrations in the isomeric potentials and to calculate moments of inertia at low spin. Moments of inertia are also investigated through cranking HFB calculations to high frequency so as to explore in this regime pairing properties of the DIS force in the heavy mass region. The WKB method is adopted in half-life calculations for the gamma-back and fission decay modes of shape isomers. All these predictions are challenged through extensive comparisons with measurements for multipole moments, moments of inertia, spin and shape isomers as well as superdeformed phonons, inner and outer potential barrier heights, and shape isomer lifetimes. Most predictions match the experimental data. Finally we predict a shallow minimum on top of the triaxial inner barriers of N similar or equal to 154 nuclei. This topological property offers a possible explanation for the unexpected structures observed in fission transmissions measured a long time ago for Cf-252 and neighboring nuclei. (c) 2006 Elsevier B.V. All rights reserved.