Excitation and decay of the first excited state of ${}^{17}$Ne

The first excited state of ${}^{17}$Ne has been populated via relativistic Coulomb excitation with a radioactive beam of ${}^{17}$Ne on a ${}^{197}$Au target and the subsequent $\gamma$-ray decay has been observed. This $\frac{3}{2}$${}^{-}$ state is bound with respect to proton emission but unbound to two-proton decay. The measured $\gamma$-ray yield accounts for ${43}_{-14}^{+19\mathrm{}}$% of the predicted yield from an excitation cross section of $28$ mb. It is unlikely that the missing cross section can be attributed to two-proton emission because the lifetime of this branch would have to be a factor 1700 smaller than predicted by standard barrier penetration calculations.