Synthesis and decay properties of isotopes of element 110: Ds273 and Ds275

The ^232Th (^48Ca, 5n) ^275Ds and ^238U (^40Ar, 5n) ^273Ds reactions have been studied at the gas-filled separator DGFRS-2 at the Superheavy Element Factory at Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research. For the first time, a new isotope ^275Ds with a half-life of 0. 43-₀. ₁₂^+0. 29 ms and -particle energy of 11. 200. 02 MeV was synthesized in the ^48Ca-induced reaction with the actinide nucleus and identified by measuring correlated decays ending in known nuclei. The decay properties of nuclei originating from ^273Ds and ^275Ds are compared with theoretical calculations and decay schemes are proposed. The cross sections of the ^232Th (^48Ca, 5n) ^275Ds reaction of 0. 11-₀. ₀₉^+0. 46 and 0. 34-₀. ₁₆^+0. 59 pb were measured at excitation energies of the ^280Ds compound nucleus E^*=51 and 56 MeV, respectively. The cross section of the 5n-evaporation channel of the ^238U+^40Ar reaction at E^*=49 MeV of 0. 18-₀. ₁₂^+0. 44 pb turned out to be comparable to that for ^275Ds at close excitation energy.