New Rare-Earth Alpha Emitter,Eu148

Abstract

A new alpha emitter with a decay energy of 2.63±0.03 MeV was discovered and assigned to the nuclide ${}_{}{}^{148}{}_{}{}^{}\mathrm{Eu}$. The $\frac{\alpha }{\mathrm{E}.\mathrm{C}.\mathrm{}}$ branching ratio was measured to be (9.4±2.8)×${10}^{-9\mathrm{}}$, corresponding to a partial alpha half-life of (1.6±0.5)×${10}^7$ years. By using a Coulomb barrier penetration formula and the measured alpha-decay energy, a half-life of (${6.2}_{-3.3\mathrm{}}^{+6.7\mathrm{}}$)×${10}^6$ years was calculated. The agreement, within experimental error, between the measured and calculated partial alpha half-lives indicates that the ground-state spin and parity assignments are probably the same for ${}_{}{}^{148}{}_{}{}^{}\mathrm{Eu}$ and its daughter ${}_{}{}^{144}{}_{}{}^{}\mathrm{Pm}$.