Half-Life of Uranium (234)

The half-life of ${\mathrm{U}}_{234}$ has been determined by two independent methods. The first method involves a re-measurement of the relative isotopic abundance of ${\mathrm{U}}_{234}$ and ${\mathrm{U}}_{238}$ in normal uranium; from this measurement the half-life of ${\mathrm{U}}_{234}$ can be obtained in terms of the known half-life of ${\mathrm{U}}_{238}$. The value obtained by this method is 2.29±0.14×${10}^5$ years. The second method involves the determination of the specific $\alpha$-activity of ${\mathrm{U}}_{234}$ from the total specific $\alpha$-activity and relative isotopic abundances of several enriched uranium samples. The value obtained by this method is 2.35±0.14×${10}^5$ years. Both values for the half-life are somewhat smaller than the currently accepted value of 2.69±0.27×${10}^5$ years.