New Isotopes of Einsteinium

Abstract

The new isotopes ${\mathrm{E}}^{249}$, ${\mathrm{E}}^{250}$, ${\mathrm{E}}^{251}$, and ${\mathrm{E}}^{252}$ were produced by bombardment of ${\mathrm{Bk}}^{249}$ with helium ions. A recoil method was used to separate the bombardment products from the target material, so that the target could be used repeatedly.