Fission barriers and other characteristics of nuclei from the uranium region

Abstract

Fission barriers in nuclei belonging to the uranium region and their other characteristics are calculated on the basis of the FaNDF⁰ energy density functional. In particular, the neutron-separation energies S_n and S_2n, the proton-separation energies S_p, and the beta-transition energiesQ_β are calculated for uranium, neptunium, and plutonium isotopes. In addition, the deformation energies and parameters of these nuclei are presented along with their radii. A comparison with the predictions of the Skyrme–Hartree–Fock method implemented with several versions of the Skyrme energy density functionals is performed. The role of the octupole deformation β₃ is studied for the ²³⁸U nucleus. It is shown that this deformation does not have any significant effect on the first-barrier height B⁽¹⁾_f or ground-state properties. At the same time, the second-barrier height B(2) f decreases by a factor of about two upon taking into account β₃. A phase transition at A ~ 260 is found for the three isotopic chains being considered: this point is a bifurcation point at which B⁽¹⁾_f (A) forks into two curves. Of these, the curve B⁽²⁾_f (A) splits from it, prolonging the former curve for B⁽¹⁾_f (A) almost continuously, whereas the curve for B⁽¹⁾_f (A) itself goes down sharply.