Short-lived $\alpha$-decaying nuclei “northeast” of ${}^{208}\mathrm{Pb}$ in the chart of nuclides were studied using the reaction ${}^{48}\mathrm{Ca}+{}^{243}\mathrm{Am}$ with the decay station TASISpec at TASCA, GSI Darmstadt. Decay energies and times from pile-up events were extracted with a tailor-made pulse-shape analysis routine and specific $\alpha$-decay chains were identified in a correlation analysis. Decay chains starting with the even-even ${}^{220}\mathrm{Ra}$ and its odd-$A$ neighbors, ${}^{219}\mathrm{Fr}$, and ${}^{221,219}\mathrm{Ra}$, with a focus on the ${}^{219}\mathrm{Ra}\to {}^{215}\mathrm{Rn}$ decay, were studied by means of $\alpha -\gamma$ spectroscopy. A revised $\alpha$-decay scheme of ${}^{219}\mathrm{Ra}$ is proposed, including a new decay branch from a previously not considered isomeric state at 17 keV excitation energy. Conclusions on nuclear structure are drawn from the experimental data, aided by Geant4 simulations and a discussion on theoretical calculations.

• Received 8 June 2018
• Revised 2 July 2018

DOI:https://doi.org/10.1103/PhysRevC.98.044307