Investigation of the ReactionHe4(He4,He4)He4* at 64 MeV

The reaction ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ (${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$) ${}_{}{}^4{}_{}{}^{}\mathrm{He}$* was investigated using a 64-MeV $\alpha$-particle beam. Absolute differential cross sections for the state near 20-MeV excitation are reported for the angular range $12.5°<{\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}<74\mathrm{}°$. We measure the excitation energy of this state to be 20.28±0.05 MeV and the width to be 0.41±0.05 MeV. The shape and position of this state are shown to be consistent with an analysis based on the known properties of low-energy $p-{}_{}{}^3{}_{}{}^{}\mathrm{H}$ scattering.