Cross sections for production of Li and Be isotopes in the α(α,pn${)}^6$Li, α(α,p${)}^7$Li, and α(α,n${)}^7$Be reactions have been measured at 198.4 MeV. These measurements are relevant to the understanding of light-element nucleosynthesis in galactic cosmic ray interactions with the interstellar medium. The data indicate that beyond energies of about 250 MeV, the α+α reaction does not contribute to the natural abundance of lithium, reinforcing theories which produce ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ in cosmic ray processes and most of nature’s ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ in the big bang. In addition, α+α elastic scattering data obtained in these experiments have been analyzed in terms of the optical model, and the results are compared with lower-energy systematics.

• Received 1 April 1985

DOI:https://doi.org/10.1103/PhysRevC.32.706