Deformation parameters of the charge distribution and the optical potential for some nuclei in and near the rare earth region

Elastic and inelastic scattering of α particles on ¹⁵⁴Sm, ¹⁶⁶Er, ¹⁶⁸Er, ¹⁸²W, ¹⁸⁴W, and ¹⁸⁶W was performed with incident energies between 11 and 21 MeV. Excitation functions for 0⁺, 2⁺, and 4⁺ states of the ground-state rotational band were measured. Pronounced destructive nuclear-Coulomb interference effects were observed. Reduced $E2$ and $E4$ transition moments, and charge and optical-potential deformation parameters were determined from coupled-channel analysis of both the sub-Coulomb and interference data.NUCLEAR REACTIONS ¹⁵⁴Sm(α, α^'), E=11-19 MeV; ¹⁶⁶Er(α, α^'), E=12.5-19.5 MeV; ¹⁸²W(α, α^'), E=13-21 MeV; measured σ(E_α, θ=150^∘). ¹⁶⁸Er(α, α^'), E=13-19 MeV; ¹⁸⁴W(α, α^'), E=12.5-19 MeV; ¹⁸⁶W(α, α^'), E=13.25-19 MeV, measured σ(E_α, θ=140^∘, 173.5^∘) deduced M(E2), M(E4), charge and optical potential deformations β₂ and β₄; coupled channel calculation.