Excitation and decay of the first excited state of ¹⁷Ne

The first excited state of ¹⁷Ne has been populated via relativistic Coulomb excitation with a radioactive beam of ¹⁷Ne on a ¹⁹⁷Au target and the subsequent γ-ray decay has been observed. This 3/2^- state is bound with respect to proton emission but unbound to two-proton decay. The measured γ-ray yield accounts for 43_-14⁺¹⁹% 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.