Probing the shell effects on fission; The New superheavy nucleus Sg

Mosat, P.*; Khuyagbaatar, J.*; Dllmann, Ch. E.*; Sato, Tetsuya   ; Yakushev, A.*; 15 of others*

Decay properties of the neutron-deficient Sg isotopes were studied at the gas-filled recoil separator TASCA at GSI, Darmstadt by using the Cr + Pb reactions. We report on the discovery of the new isotope Sg. Its ground state, tentatively assigned to have 9/2[734]configuration, was observed to decay by both spontaneous fission and-particle emission with a half-life of 12.6 ms. The alpha decay from this high-spin state was followed by fission of Rf. In Sg, we observed strong evidence for the occurrence of a -isomeric state for the first time in superheavy nuclei with 106 protons. The current experimental findings, discussed within the experimental systematics and theory, indicate that hitherto unseen features of the shell effect on the fission process may be found in the neutron-deficient superheavy nuclei.