Folding model analysis of the excitation of low-lying states and the high energy octupole resonance in116Snby 240 MeV α scattering

Abstract

The sum rule strength of the high energy octupole resonance (HEOR) and the transition rates of low-lying ${2}^{+}$ and ${3}^{\ensuremath{-}}$ states of ${}^{116}\mathrm{Sn},$ excited by 240 MeV \ensuremath{\alpha} scattering, have been determined from deformed potential and folding model analyses. Deformed potential cross sections for both the low-lying ${3}^{\ensuremath{-}}$ state and the HEOR are greater than folding cross sections by a factor of 1.18. The high energy octupole resonance was found to exhaust $(70\ifmmode\pm\else\textpm\fi{}15)%$ and $(83\ifmmode\pm\else\textpm\fi{}15)%$ of the $E3$ energy-weighted sum rule from the two analyses, respectively. The data for the low-lying states are fit well by the calculations made with both models using electromagnetic values for the transition rates. Optical-model parameters were obtained from fits to elastic scattering data. The differential cross sections for the elastic scattering and inelastic scattering exciting the low-lying ${2}^{+}$ and ${3}^{\ensuremath{-}}$ states in ${}^{116}\mathrm{Sn}$ were measured over the angle range from ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}=1.6\ifmmode^\circ\else\textdegree\fi{}$ to 35.2\ifmmode^\circ\else\textdegree\fi{}.