Synthesis and study of decay properties of the doubly magic nucleus 270 Hs in the 226 Ra + 48 Ca reaction

Production and decay of the isotopes of Hs were studied in the Ra-226 + Ca-48 reaction at beam energies E-lab = 229, 234, and 241 MeV. At the E-lab = 234 MeV energy, the maximum of the 4n-evaporation channel of the reaction, six identical alpha-SF decay chains of the nucleus (270)Hs were detected corresponding to a cross section of sigma(4n) = 16(-7)(+13) pb. At the other Ca-48 energies, no Hs isotopes were observed. Nuclei of (270)Hs undergo a decay with alpha Q(alpha) = 9.15 +/- 0.08 MeV and the half-life of the daughter spontaneous fission (SF) isotope (266)Sg is 0.28(-0.08)(+0.19) s, in good agreement with the data previously observed in the Cm-248(Mg-26,4n)(270)Hs reaction. The partial alpha-decay half-life of (270)Hs was measured for the first time: T-alpha = 7.6(-2.2)(+4.9) s. For the spontaneous fission, we determined a lower limit T-SF >= 10 s. Decay properties of (270)Hs corroborate theoretical predictions of its relatively high stability caused by the effect of the deformed shells at Z = 108 and N = 162. DOI: 10.1103/PhysRevC.87.034605