Measurements of cross sections for the fusion-evaporation reactions ²⁴⁴Pu(⁴⁸Ca,xn)^292−x114 and ²⁴⁵Cm(⁴⁸Ca,xn)^293−x116

We have studied the excitation functions of the reactions ²⁴⁴Pu(⁴⁸Ca,xn). Maximum cross sections for the evaporation of 3–5 neutrons in the complete-fusion reaction ²⁴⁴Pu+⁴⁸Ca were measured to be σ_3n=2 pb, σ_4n=5 pb, and σ_5n=1 pb. The decay properties of 3n-evaporation product ²⁸⁹114, in the decay chains observed at low ⁴⁸Ca energy coincide well with those previously observed in the ²⁴⁴Pu+⁴⁸Ca and ²⁴⁸Cm+⁴⁸Ca reactions and assigned to ²⁸⁸114. Two isotopes of element 114 and their descendant nuclei were identified for the first time at higher bombarding energies: ²⁸⁸114 (E_α=9.95 MeV, T_1∕2=0.6 s) and ²⁸⁷114 (E_α=10.04 MeV, T_1∕2=1 s). We also report on the observation of new isotopes of element 116, ^290,291116, produced in the ²⁴⁵Cm+⁴⁸Ca reaction with cross sections of about 1 pb. A discussion of self-consistent interpretations of all observed decay chains originating at Z=118, 116, and 114 is presented.