The radioactive nuclide ${\mathrm{Ne}}^{18}$ has been produced in the ${\mathrm{O}}^{16}({\mathrm{He}}^3, n){\mathrm{Ne}}^{18}$ reaction by 5.2-Mev ${\mathrm{He}}^3$ particles from the NRL 5-Mv Van de Graaff accelerator. The target, CaO on a Pt backing, was about 300 kev thick to the incident beam. The gamma rays following the decay of ${\mathrm{Ne}}^{18}$ were detected by a 3-in. diam by 3-in. NaI(Tl) crystal and a 256-channel pulse-height analyzer. Only one nuclear gamma ray was observed. Its energy, measured with respect to the ${\mathrm{Na}}^{22}$ gamma ray at 1.2736±0.0016 Mev, is 1.041±0.005 Mev. Therefore, this gamma ray is assigned to the 1.04-Mev state of ${\mathrm{F}}^{18}$. This state is considered to be the isobaric spin analog state of the ${\mathrm{Ne}}^{18}$ ground state, and therefore has quantum parameters $0^{+}$, $T=1\mathrm{}$. The branching to this excited state was measured to be 0.07±0.02 (including a calculated contribution of 0.00006 from orbital electron capture), and that to the ground state of ${\mathrm{F}}^{18}$ was measured to be 0.93±0.02 (including a calculated contribution of 0.0002 from orbital electron capture). The $\mathrm{ft}$ values are, respectively, 3030±880 and 1120±70 sec. The half-life of ${\mathrm{Ne}}^{18}$ was measured to be 1.46±0.07 sec.

• Received 2 November 1960

DOI:https://doi.org/10.1103/PhysRev.121.1782