Differential cross sections for ${}_{}{}^3{}_{}{}^{}\mathrm{\alpha }$ scattering were measured in the energy range up to 3 MeV. These data together with other available experimental results for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$+α and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$+α scattering were analyzed in the framework of the optical model using double-folded potentials. The optical potentials obtained were used to calculate the astrophysical S factors of the capture reactions ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(α,γ${)}^7$Be and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$(α,γ${)}^7$Li, and the branching ratios for the transitions into the two final ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ bound states, respectively. For ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(α,γ${)}^7$Be excellent agreement between calculated and experimental data is obtained. For ${}_{}{}^3{}_{}{}^{}\mathrm{H}$(α,γ${)}^7$Li an S(0) value has been found which is a factor of about 1.5 larger than the adopted value. For both capture reactions a similar branching ratio of R=σ(${\gamma }_1$)/σ(${\gamma }_0$)≊0.43 has been obtained.

• Received 13 May 1993

DOI:https://doi.org/10.1103/PhysRevC.48.1420