Electron scattering from transitional nuclei

An electron scattering experiment on ¹⁸⁸Os, ¹⁹⁰Os, ¹⁹²Os, ¹⁹⁴Pt and ¹⁹⁶Pt has been performed at momentum transfers q = 0.6 to 3.2 fm⁻¹. Transition charge densities have been determined for the low-lying 2⁺, 3⁻ and 4⁺ states. The 2⁺ densities are well reproduced within the framework of the interacting boson model 2, where we have determined the boson densities α_ν, α_π, β_νv and β_π. The 4⁺ transition densities could not be reproduced indicating the need for including a g-boson. The ground and transition charge densities of ¹⁸⁸Os, ¹⁹²Os and ¹⁹⁶Pt have been compared with a microscopic calculation. The total binding energies and the intrinsic wave functions have been calculated for different values of β and γ with the constrained triaxial Hartree-Fock-Bogoliubov method using the finite range interaction D1SA. These energies are interpreted as potential energy surfaces and used in the Bohr hamiltonian in order to obtain the total nuclear wave functions. We obtain very good agreement with experiment. The calculated potential energy surfaces show these nuclei to be γ-soft with a shallow minimum for triaxial deformations and rigid in the β direction.