Measurements of cross sections for the fusion-evaporation reactionsPu244(Ca48,xn)292−x114andCm245(Ca48,xn)293−x116

We have studied the excitation functions of the reactions ${}^{244}\mathrm{Pu}$(${}^{48}\mathrm{Ca}$,$xn$). Maximum cross sections for the evaporation of 3–5 neutrons in the complete-fusion reaction ${}^{244}\mathrm{Pu+}{}^{48}\mathrm{Ca}$ were measured to be ${\sigma }_{3n}=2\text{pb}$, ${\sigma }_{4n}=5\text{pb}$, and ${\sigma }_{5n}=1\text{pb}$. The decay properties of $3n$-evaporation product ${}^{289}114$, in the decay chains observed at low ${}^{48}\mathrm{Ca}$ energy coincide well with those previously observed in the ${}^{244}\mathrm{Pu+}{}^{48}\mathrm{Ca}$ and ${}^{248}\mathrm{Cm+}{}^{48}\mathrm{Ca}$ reactions and assigned to ${}^{288}114$. Two isotopes of element 114 and their descendant nuclei were identified for the first time at higher bombarding energies: ${}^{288}114$ ($E_{\alpha }=9.95\text{MeV}$, $T_{1∕2}=0.6\mathrm{s}$) and ${}^{287}114$ ($E_{\alpha }=10.04\text{MeV}$, $T_{1∕2}=1\mathrm{s}$). We also report on the observation of new isotopes of element 116, ${}^{290,291}116$, produced in the ${}^{245}\mathrm{Cm}+{}^{48}\mathrm{Ca}$ reaction with cross sections of about $1\text{pb}$. A discussion of self-consistent interpretations of all observed decay chains originating at $Z=118$, 116, and 114 is presented.