A study has been made of the proton and $\alpha$-particle yields from the 28-MeV (lab) bombardment of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ by ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. From these measurements a total reaction cross section ${\sigma }_R$ of $433\pm 10$ mb was deduced. A reaction-model analysis of the $\alpha$-particle continuum revealed a significant contribution from the sequential reaction ${}_{}{}^3{}_{}{}^{}\mathrm{He}+{}_{}{}^4{}_{}{}^{}\mathrm{He}\to {}_{}{}^6{}_{}{}^{}\mathrm{Li}\mathrm{}\left(2.18\right)+p\to \alpha +d+p$ in which the breakup of the excited ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ nucleus is nearly isotropic in its rest system. A phase-shift study was performed for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ + ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ elastic scattering at this energy using our ${\sigma }_R$ value as a constraint. A pronounced odd-even dependence of the real parts of the phase shifts on the orbital angular momentum was found. The results of this work are compared with other experiments, optical-model and phase-shift analyses, and resonating-group calculations.

[NUCLEAR REACTIONS ${}_{}{}^4{}_{}{}^{}\mathrm{He}({}_{}{}^3{}_{}{}^{}\mathrm{He},p)$, (${}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha$), $E=28.00\mathrm{}$ MeV; measured $\sigma (E_p,\theta )$, $\sigma (E_{\alpha },\theta )$; deduced ${\sigma }_R$. $\alpha$-continuum analysis. Phase-shift analysis. Resonating-group comparison.]

• Received 31 March 1977

DOI:https://doi.org/10.1103/PhysRevC.16.18