Decay Spectroscopy Studies of the Two New Isotopes of Astatine

Decay properties of two new isotopes of astatine, \(^{188}\)At and \(^{190}\)At, were studied in the Accelerator Laboratory of the University of Jyväskylä, Finland. The nuclei were produced in fusion–evaporation reactions, and those were separated from the primary beam and target-like products by employing the RITU (Recoil-Ion Transport Unit) recoil separator. Decay-spectroscopy studies were performed for the produced nuclei resulting in information about the decay properties of \(^{188}\)At and \(^{190}\)At. The \(^{188}\)At isotope was found to be the heaviest proton emitter to date. Additionally, the \(^{190}\)At isotope was observed to decay via \(\alpha \) decay. The results were compared with the systematics and with non-adiabatic quasiparticle calculations. In \(^{188}\)At, a deviation in the one-proton separation energy was observed, indicating the first possible sign of the Thomas–Ehrman shift in heavy nuclei. Abstract Published by the Jagiellonian University 2026 authors