Exact finite-range cluster transfer distorted-wave Born approximation calculations were done for the reactions ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$)${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ at 34 MeV and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^1{}_{}{}^{}\mathrm{H}$)${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ at 19.8 MeV. Exchange contributions were included. The exchange process was found to be important for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$)${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ reaction and it significantly improved the fit to the data. Spectroscopic factors for the exchange process in this reaction were extracted. Exchange is predicted to be inhibited by kinematic considerations for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^1{}_{}{}^{}\mathrm{H}$)${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$; the calculation confirmed that the exchange process was several orders of magnitude too small to affect the fit to the data.

NUCLEAR REACTIONS Exact finite-range DWBA calculations of differential cross sections for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^6{}_{}{}^{}\mathrm{Li}, \alpha ){}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ at 34 MeV and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^3{}_{}{}^{}\mathrm{He}, p){}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ at 19.8 MeV including exchange contributions.

• Received 20 September 1976

DOI:https://doi.org/10.1103/PhysRevC.15.686