Level Energies and B(E2) Ratios of the Deformed Even Nuclei in the Actinide Region

Abstract

Level energies and B(E2) ratios are calculated for the deformed even nuclei in the actinide region. A collective Hamiltonian H = Trot + Tvib + V is employed. The rotation and vibration are treated adiabatically. An anharmonic term, which is introduced to the potential of the β-vibration, gives rise to the dependence of the moments of inertia on the total angular momentum I and the quantum number nβ of the β-vibration. The ratios of the anharmonic term to the harmonic term of the nuclei in the actinide region are about twice as large as those of nuclei in the rare earth region. The phonon energies of the γ-vibration of the nuclei in the actinide region are lower compared with those of nuclei in the rare earth region. In some nuclei, the state with K = I = 0 and with the level energy approximately equal to the calculated γ-phonon energy is found experimentally. Especially, 234U, a level corresponding to the γ-vibrational 0+ state is found in good agreement with the calculated value. Calculated level energies agree well with experimental values, and B(E2) ratios are much improved in comparison with the corresponding values calculated from the Clebsch-Gordan coefficients.