Odd-even absorption and Coulomb-exchange effects in the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ + ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ + ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ systems

Differential cross sections for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ + ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ elastic scattering are calculated at c.m. energies up to 44.5 MeV using the one-channel resonating-group method. A phenomenological imaginary potential, whose strength depends on whether the relative orbital angular momentum is even or odd, is included in the calculation in order to account approximately for open reaction channels. Exchange terms which arise from the nucleon-nucleon Coulomb interaction also are included. The introduction of both the odd-even absorption and the Coulomb-exchange terms is found to lead to significantly improved agreement with experiment. In addition, the use of improved rms matter radii for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ is found to yield ${}_{}{}^2{}_{}{}^{}P_J^{}{}_{}{}^{}$ bound-state energies for the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ + ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ + ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ systems which are more consistent with experiment than found previously.

[NUCLEAR STRUCTURE, REACTIONS ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$; calculated ${}_{}{}^2{}_{}{}^{}P_J^{}{}_{}{}^{}$, ${}_{}{}^2{}_{}{}^{}F_J^{}{}_{}{}^{}$ levels. ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$), $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=1.7-44.5\mathrm{}$ MeV; calculated $\sigma \left(\Theta \right)$; deduced imaginary-potential strength, space-exchange mixture. Resonating-group method.]