The new, neutron-deficient, superheavy element isotope ${}^{285}114$ was produced in ${}^{48}\mathrm{Ca}$ irradiations of ${}^{242}\mathrm{Pu}$ targets at a center-of-target beam energy of 256 MeV ($E^{*}=50\mathrm{MeV}$). The $\alpha$ decay of ${}^{285}114$ was followed by the sequential $\alpha$ decay of four daughter nuclides, ${}^{281}\mathrm{Cn}$, ${}^{277}\mathrm{Ds}$, ${}^{273}\mathrm{Hs}$, and ${}^{269}\mathrm{Sg}$. ${}^{265}\mathrm{Rf}$ was observed to decay by spontaneous fission. The measured $\alpha$-decay $Q$ values were compared with those from a macroscopic-microscopic nuclear mass model to give insight into superheavy element shell effects. The ${}^{242}\mathrm{Pu}({}^{48}\mathrm{Ca},5n){}^{285}114$ cross section was ${0.6}_{-0.5}^{+0.9}\mathrm{pb}$.

• Received 23 July 2010

DOI:https://doi.org/10.1103/PhysRevLett.105.182701