Search for Superheavy Elements in the Bombardment ofCm248withCa48

We have searched for superheavy elements 110 to 116 with half-lives between ${10}^4$ and ${10}^8$ s in fractions chemically separated after each of a series of bombardments of ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$ made with 267-MeV ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ ions. After 6 months of $\alpha$ and spontaneous-fission counting, our results provide no persuasive evidence for the presence for the presence of superheavy elements. The most plausible explanation for not finding the superheavy elements is that they have either short half-lives or very small formation cross sections.