The reactions ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$(${}_{}{}^4{}_{}{}^{}\mathrm{He}$,${}_{}{}^8{}_{}{}^{}\mathrm{He}$)${}_{}{}^{50}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$(${}_{}{}^4{}_{}{}^{}\mathrm{He}$,${}_{}{}^8{}_{}{}^{}\mathrm{He}$)${}_{}{}^{54}{}_{}{}^{}\mathrm{Ni}$ have been observed at an incident $\alpha$ energy of 110 MeV. The reaction $Q$ values are found to be $Q\left({}_{}{}^{50}{}_{}{}^{}\mathrm{Fe}\right)=-50.95\mathrm{}\pm 0.06$ MeV and $Q\left({}_{}{}^{54}{}_{}{}^{}\mathrm{Ni}\right)=-50.19\mathrm{}\pm 0.05$ MeV. The experiments provide the first observation and subsequent mass measurement of the proton-rich nuclei ${}_{}{}^{50}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Ni}$.

NUCLEAR REACTIONS ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$(${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^8{}_{}{}^{}\mathrm{He}$) and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Ni}$(${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^8{}_{}{}^{}\mathrm{He}$). Measured reaction $Q$ values and mass excesses of ${}_{}{}^{50}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Ni}$.

• Received 6 December 1976

DOI:https://doi.org/10.1103/PhysRevC.16.917