Beta Decay ofO19: States ofF19

The beta decay of ${\mathrm{O}}^{19}$ has been re-examined in order to search for transitions to highly excited states of ${\mathrm{F}}^{19}$ which are predicted by the independent-particle model (IPM) to have large matrix elements. Such a transition is found in the 0.16% beta branch to the 4.39-MeV state of ${\mathrm{F}}^{19}$: $logft=3.54\mathrm{}\pm 0.06$. This state deexcites through gamma branches of (18±7%) to the 2.79-MeV state of ${\mathrm{F}}^{19}$ and (82±7)% to the 0.197-MeV state; branches to other states below that at 2.79 MeV are less than 5%. These data make it certain that the 4.39-MeV state is of $J^{\pi }=\frac{3}{2}, \frac{5}{2}, {\frac{7}{2}}^{+}$ (assuming that the ground state of ${\mathrm{O}}^{19}$ is of $J^{\pi }={\frac{5}{2}}^{+}$). If, as is most likely, the 2.79-MeV state of ${\mathrm{F}}^{19}$ is of $J^{\pi }={\frac{9}{2}}^{+}$, then $J^{\pi }={\frac{7}{2}}^{+}$ is strongly favored for the 4.39-MeV level. An IPM state of $J^{\pi }={\frac{7}{2}}^{+}$ enjoying a strong beta decay from ${\mathrm{O}}^{19}$ is predicted at just this energy. Beta decay to the 2.79-MeV state of ${\mathrm{F}}^{19}$ has $log\mathrm{ft}>\mathrm{}7.4\mathrm{}$. The decay of the 1.56-MeV state of ${\mathrm{F}}^{19}$ is also examined and a ground-state branch of (2.4±0.5)% is determined. This transition is expected to be weak by both the IPM and the collective models. The ${\mathrm{O}}^{19}$ used in this experiment was made by the reaction ${\mathrm{O}}^{18}(d, p){\mathrm{O}}^{19}$, and the experimental techniques were exclusively those of NaI spectroscopy, including two-dimensional analysis.