²⁴⁸Cm(²²Ne,xn)^270-xSg reaction and the decay properties of ²⁶⁵Sg reexamined

Recent studies of the hot fusion reaction ²⁴⁸Cm(²⁶Mg,xn)^274-xHs have provided new nuclear decay data on ^265,266Sg and confirmed the existence of an isomeric state in ²⁶¹Rf. The results reported in [J. Dvorak et al., Phys. Rev. Lett. 100, 132503 (2008)] suggest that all decay chains observed in previous studies of the reaction ²⁴⁸Cm(²²Ne,xn)^270-xSg, which were originally attributed to ²⁶⁶Sg, originated from ²⁶⁵Sg. Here, the decay properties of ²⁶⁵Sg are reevaluated. Indications for the existence of an isomeric state in ²⁶⁵Sg are found. The half-lives and main α particle energies of the two ²⁶⁵Sg states are 8.9 s/8.85 MeV and 16.2 s/8.70 MeV, respectively. Direct production of this isotope as an evaporation residue of a nuclear fusion reaction populates both states with similar intensity while α decay of ²⁶⁹Hs into ²⁶⁵Sg preferentially populates the longer-lived state, which in turn decays almost exclusively into the short-lived state in ²⁶¹Rf. The cross section of the reaction ²⁴⁸Cm(²²Ne,5n)²⁶⁵Sg is reanalyzed and found to be of the order of a few hundred pb, assuming that α decay is the only decay mode of ²⁶⁵Sg. A decay scheme that is consistent with the published data on ²⁶⁵Sg and ²⁶¹Rf is proposed, which can serve as a working hypothesis in the design of new experiments dedicated to study the production and decay of these two isotopes.