Abstract
In this Letter, the observation of two previously unknown isotopes is presented for the first time: with 14 observed events and with one observed event. From the nonobservation of the less proton-rich nucleus , we derive an upper limit for the ground-state half-life of 81 ns, consistent with the previous upper limit of 30 ns. For , we have measured a half-life of 103(22) ns. This observation of a relatively long-lived odd-odd nucleus, , with a less exotic odd-even neighbor, , being unbound shows the diffuseness of the proton drip line and the possibility of sandbanks to exist beyond it. The half-life is consistent with a proton decay with an energy of 800–900 keV, in agreement with the atomic mass evaluation proton-separation energy as well as results from the finite-range droplet model and shell model calculations using the GXPF1A interaction. However, we cannot explicitly exclude the possibility of a proton transition between isomeric states with a broken mirror symmetry. These results imply that is a strong waiting point in x-ray burst -process scenarios.
- Received 3 April 2017
DOI:https://doi.org/10.1103/PhysRevLett.119.192503
© 2017 American Physical Society