2023

Cox, D. M.; Såmark-Roth, A.; Rudolph, D.; Sarmiento, L. G.; Clark, R. M.; Egido, J. L.; Golubev, P.; Heery, J.; Yakushev, A.; Åberg, S.; Albers, H. M.; Albertsson, M.; Block, M.; Brand, H.; Calverley, T.; Cantemir, R.; Carlsson, B. G.; Düllmann, Ch. E.; Eberth, J.; Fahlander, C.; Forsberg, U.; Gates, J. M.; Giacoppo, F.; Götz, M.; Götz, S.; Herzberg, R.-D.; Hrabar, Y.; Jäger, E.; Judson, D.; Khuyagbaatar, J.; Kindler, B.; Kojouharov, I.; Kratz, J. V.; Krier, J.; Kurz, N.; Lens, L.; Ljungberg, J.; Lommel, B.; Louko, J.; Meyer, C.-C.; Mistry, A.; Mokry, C.; Papadakis, P.; Parr, E.; Pore, J. L.; Ragnarsson, I.; Runke, J.; Schädel, M.; Schaffner, H.; Schausten, B.; Shaughnessy, D. A.; Thörle-Pospiech, P.; Trautmann, N.; Uusitalo, J.

Fifteen correlated α-decay chains starting from the odd-A superheavy nucleus 289Fl were observed following the fusion-evaporation reaction 48Ca+244Pu. The results call for at least two parallel α-decay sequences starting from at least two different states of 289Fl. This implies that close-lying levels in nuclei along these chains have quite different spin-parity assignments. Further, observed α-electron and α-photon coincidences, as well as the α-decay fine structure along the decay chains, suggest a change in the ground-state spin assignment between 285Cn and 281Ds. Our experimental results, on the excited level structure of the heaviest odd-N nuclei to date, provide a direct testing ground for theory. This is illustrated by comparison with new nuclear structure calculations based on the symmetry-conserving configuration mixing theory.