Excitation functions for production of Rf isotopes in the248Cm+18O reaction

Production cross sections of Rf isotopes in the ${}^{248}$Cm$\phantom{\rule{0.16em}{0ex}}+\phantom{\rule{0.16em}{0ex}}$${}^{18}$O reaction were measured at the beam energy range of 88.2 to 101.3 MeV by use of a gas-filled recoil ion separator. The excitation functions of ${}^{260}$Rf, ${}^{261}$Rf${}^{a}$, and ${}^{262}$Rf were obtained together with those of spontaneously fissioning nuclides which have few-second half-lives and have been assigned to ${}^{261}$Rf${}^{b}$ and a longer-lived state of ${}^{262}$Rf. The excitation function of few-second spontaneously fissioning nuclide exhibited the maximum cross section at the ${}^{18}$O beam energy of 94.8 MeV. The shape of the excitation function was almost the same as that of ${}^{261}$Rf${}^{a}$, whereas it was quite different from those of ${}^{260}$Rf and ${}^{262}$Rf. A few-second spontaneously fissioning nuclide previously reported as ${}^{261}$Rf${}^{b}$ and ${}^{262}$Rf observed in ${}^{248}$Cm$\phantom{\rule{0.16em}{0ex}}+\phantom{\rule{0.16em}{0ex}}$${}^{18}$O reaction was identified as ${}^{261}$Rf${}^{b}$.