Measurements of cross sections for the fusion-evaporation reactions pu-244(ca-48, xn) 114-(292-x) and cm-245(ca-48, xn) 116-(293-x)

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 ${\ensuremath{\sigma}}_{3n}=2\phantom{\rule{0.3em}{0ex}}\text{pb}$, ${\ensuremath{\sigma}}_{4n}=5\phantom{\rule{0.3em}{0ex}}\text{pb}$, and ${\ensuremath{\sigma}}_{5n}=1\phantom{\rule{0.3em}{0ex}}\text{pb}$. 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: $^{288}114$ (${E}_{\ensuremath{\alpha}}=9.95\phantom{\rule{0.3em}{0ex}}\text{MeV}$, ${T}_{1∕2}=0.6\phantom{\rule{0.3em}{0ex}}\mathrm{s}$) and $^{287}114$ (${E}_{\ensuremath{\alpha}}=10.04\phantom{\rule{0.3em}{0ex}}\text{MeV}$, ${T}_{1∕2}=1\phantom{\rule{0.3em}{0ex}}\mathrm{s}$). 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 $1\phantom{\rule{0.3em}{0ex}}\text{pb}$. A discussion of self-consistent interpretations of all observed decay chains originating at $Z=118$, 116, and 114 is presented.