Ca 48 + Bk 249 fusion reaction leading to element Z=117: Long-lived α -decaying Db 270 and discovery of Lr 266

Khuyagbaatar, J.; Yakushev, A.; Dullmann, Ch. E.; Ackermann, D.; Andersson, L. -L.; Asai, M.; Block, M.; Boll, R. A.; Brand, H.; Cox, D. M.; Dasgupta, M.; Derkx, X.; Di Nitto, A.; Eberhardt, K.; Even, J.; Evers, M.; Fahlander, C.; Forsberg, U.; Gates, J. M.; Gharibyan, N.; Golubev, P.; Gregorich, K. E.; Hamilton, J. H.; Hartmann, W.; Herzberg, R. -D.; Hessberger, F. P.; Hinde, D. J.; Hoffmann, J.; Hollinger, R.; Hubner, A.; Jager, E.; Kindler, B.; Kratz, J. V.; Krier, J.; Kurz, N.; Laatiaoui, M.; Lahiri, S.; Lang, R.; Lommel, B.; Maiti, M.; Miernik, K.; Minami, S.; Mistry, A.; Mokry, C.; Nitsche, H.; Omtvedt, J. P.; Pang, G. K.; Papadakis, P.; Renisch, D.; Roberto, J.; Rudolph, D.; Runke, J.; Rykaczewski, K. P.; Sarmiento, L. G.; Schadel, M.; Schausten, B.; Semchenkov, A.; Shaughnessy, D. A.; Steinegger, P.; Steiner, J.; Tereshatov, E. E.; Thorle-Pospiech, P.; Tinschert, K.; Torres De Heidenreich, T.; Trautmann, N.; Turler, A.; Uusitalo, J.; Ward, D. E.; Wegrzecki, M.; Wiehl, N.; Van Cleve, S. M.; Yakusheva, V.

doi:10.1103/PhysRevLett.112.172501

The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."

Ca 48 + Bk 249 fusion reaction leading to element Z=117: Long-lived α -decaying Db 270 and discovery of Lr 266 / Khuyagbaatar, J.; Yakushev, A.; Dullmann, Ch. E.; Ackermann, D.; Andersson, L. -L.; Asai, M.; Block, M.; Boll, R. A.; Brand, H.; Cox, D. M.; Dasgupta, M.; Derkx, X.; Di Nitto, A.; Eberhardt, K.; Even, J.; Evers, M.; Fahlander, C.; Forsberg, U.; Gates, J. M.; Gharibyan, N.; Golubev, P.; Gregorich, K. E.; Hamilton, J. H.; Hartmann, W.; Herzberg, R. -D.; Hessberger, F. P.; Hinde, D. J.; Hoffmann, J.; Hollinger, R.; Hubner, A.; Jager, E.; Kindler, B.; Kratz, J. V.; Krier, J.; Kurz, N.; Laatiaoui, M.; Lahiri, S.; Lang, R.; Lommel, B.; Maiti, M.; Miernik, K.; Minami, S.; Mistry, A.; Mokry, C.; Nitsche, H.; Omtvedt, J. P.; Pang, G. K.; Papadakis, P.; Renisch, D.; Roberto, J.; Rudolph, D.; Runke, J.; Rykaczewski, K. P.; Sarmiento, L. G.; Schadel, M.; Schausten, B.; Semchenkov, A.; Shaughnessy, D. A.; Steinegger, P.; Steiner, J.; Tereshatov, E. E.; Thorle-Pospiech, P.; Tinschert, K.; Torres De Heidenreich, T.; Trautmann, N.; Turler, A.; Uusitalo, J.; Ward, D. E.; Wegrzecki, M.; Wiehl, N.; Van Cleve, S. M.; Yakusheva, V.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 112:17(2014), p. 172501. [10.1103/PhysRevLett.112.172501]