Using an energy scale based on an electrical "zero" and the ($\gamma , n$) thresholds of ${\mathrm{F}}^{19}$, ${\mathrm{N}}^{14}$, and ${\mathrm{C}}^{12}$, five ($\gamma , n$) thresholds were measured: ${\mathrm{Ag}}^{109}$, 9.14±0.05 Mev; ${\mathrm{Ag}}^{107}$ to 24-min ${\mathrm{Ag}}^{106}$, 9.43±0.05; ${\mathrm{Cu}}^{65}$, 9.89±0.11; ${\mathrm{Cu}}^{63}$, 10.80±0.04; and ${\mathrm{In}}^{115}$ to 49-day ${\mathrm{In}}^{114m}$, 9.22±0.10. Breaks, interpreted to be levels in the initial nucleus, were found at 10.47±0.02 Mev in ${\mathrm{F}}^{19}$ and 16.17±0.05 Mev in ${\mathrm{O}}^{16}$. The observed ${\mathrm{O}}^{16}(\gamma , n){\mathrm{O}}^{15}$ threshold was in poor agreement with the known $Q$ value. Two half-lives were measured: ${\mathrm{F}}^{18}$, 1.83±0.02 hours and ${\mathrm{In}}^{114m}$, 49±1 days.

• Received 14 May 1958

DOI:https://doi.org/10.1103/PhysRev.111.1297