Systematic study of the nuclear potential diffuseness through high precision back-angle quasi-elastic scattering

Abstract

High precision measurements for back-angle quasi-elastic scattering of $^{16}\mathrm{O}$ from various target nuclei have been made, and are compared with coupled channels calculations to determine the diffuseness of the real part of the Woods-Saxon nuclear potential. The extracted diffuseness parameters are in the range of $0.60$ to $0.69$ fm, and agree well with previous results using a $^{32}\mathrm{S}$ projectile. The measured quasi-elastic energy spectra close to the barrier show both discrete peaks and a broad continuous structure with $Q$-values down to $\ensuremath{-}25$ MeV. These suggest the inadequacy of coupled channels calculations that include couplings only to low energy, discrete states of the colliding nuclei.