The ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}(\alpha , {}_{}{}^8{}_{}{}^{}\mathrm{He}){}_{}{}^{14}{}_{}{}^{}\mathrm{O}_{\mathrm{g}.\mathrm{s}.\mathrm{}}^{}{}_{}{}^{}$ reaction has been observed at $E_{\alpha }=58\mathrm{}$ MeV. The measured cross section is 40 ± 15 nb/sr at ${\theta }_{\mathrm{lab}}=8\mathrm{}°$. The mass excess of ${}_{}{}^8{}_{}{}^{}\mathrm{He}$ was determined to be 31 600 ± 25 keV. Possible reaction mechanisms are discussed.

NUCLEAR REACTIONS ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$(${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^8{}_{}{}^{}\mathrm{He}$), $E=58\mathrm{}$ MeV. Measured $\sigma (E_f, 8°)$. Deduced $Q_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ and mass excess for ${}_{}{}^8{}_{}{}^{}\mathrm{He}$. Magnetic spectrometer.

• Received 3 February 1975

DOI:https://doi.org/10.1103/PhysRevC.11.2114