Speaker
Description
In this contribution we will discuss the observation of the previously unknown isotope $^{72}$Rb, with 14 observed events in BigRIPS and the ZeroDegree spectrometer during the EURICA campaign at RIKEN [1]. For context, the role of the neighbouring nuclei $^{72}$Kr and $^{73}$Rb will be discussed in their role as a waiting point in x-ray burst rp-process scenarios. The nonobservation of the less proton-rich nucleus $^{73}$Rb is consistent with the adapted upper limit of 30 ns. For $^{72}$Rb, however, we measure a half-life of 103 ns. This observation of a relatively long-lived odd-odd nucleus, $^{72}$Rb, with a less exotic odd-even neighbor, $^{73}$Rb, being unbound shows the diffuseness of the proton drip line and the possibility of sandbanks to exist beyond it. The $^{72}$Rb half-life is consistent with a $5^{+} \rightarrow 5/2^{-}$ proton decay with an energy of 800–900 keV, in agreement with the atomic mass evaluation proton-separation energy.
[1] H. Suzuki, et al. Phys. Rev. Lett., 119:192503, 2017.
