The ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$) reaction has been used to study the particle-unstable nucleus ${}_{}{}^{15}{}_{}{}^{}\mathrm{F}$. The ground state of ${}_{}{}^{15}{}_{}{}^{}\mathrm{F}$ is observed as a broad peak at a mass excess of 16.9±0.2 MeV with a width greater than 900 keV. A well defined narrower peak is observed at a mass excess of 18.088±0.025 MeV and with a width of 240±30 keV. It is shown to be the mirror of the ${5/2}^{+}$ first excited state of ${}_{}{}^{15}{}_{}{}^{}\mathrm{C}$. The analog of the ${5/2}^{+}$ state was observed in ${}_{}{}^{15}{}_{}{}^{}\mathrm{O}$ at $E_x=12.255\mathrm{}\pm 0.013$ MeV. This state is shown to proton decay to the $T=1\mathrm{}$ first excited state of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ and to have a width of 135±15 keV.

NUCLEAR REACTIONS ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}({}_{}{}^3{}_{}{}^{}\mathrm{He},{}_{}{}^8{}_{}{}^{}\mathrm{Li}){}_{}{}^{15}{}_{}{}^{}\mathrm{F}{}_{}{}^{17}{}_{}{}^{}\mathrm{O}\mathrm{}(p,t)\mathrm{}{}_{}{}^{15}{}_{}{}^{}\mathrm{O}$ ($T=\frac{3}{2}$) measured reaction $Q$ values, ${\Gamma }_{\mathrm{c}.\mathrm{m}.\mathrm{}}$; deduced mass excesses, excitation energies. Deduced coefficients IMME.

• Received 28 November 1977

DOI:https://doi.org/10.1103/PhysRevC.17.1939