Angular distributions of the vector analyzing powers for the ${}_{}{}^3{}_{}{}^{}\mathrm{H}$${(}^3$He${,}^2$H${)}^4$He reaction have been measured over the incident energy range 18–33 MeV. The measurements centered about 18 MeV display a deviation from the antisymmetric shape expected from isospin symmetry. Concentrating on the explanation of the 90° analyzing powers, we report the results of a distorted-wave Born approximation (DWBA) analysis which includes the direct and exchange processes and the spin-orbit potential. It is shown that the anomalous behavior of the 90° vector analyzing powers can be largely explained by the effect of a single F-wave potential resonance which leads to the magnification of the short-range differences between the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ wave functions.

• Received 6 July 1988

DOI:https://doi.org/10.1103/PhysRevC.38.2036