Half-life ofGd148

Gadolinium isotopes were separated from a tantalum target which had been irradiated with 800-MeV protons. The concentrations of ${}_{}{}^{148}{}_{}{}^{}\mathrm{Gd}$ in weighed aliquots of a solution of the isotopes were determined by isotope dilution mass spectrometry. Other aliquots were counted on a low geometry alpha counter to determine the disintegration rate of ${}_{}{}^{148}{}_{}{}^{}\mathrm{Gd}$ per unit weight of solution. From the data obtained the half-life of the isotope was found to be 74.6±3.0 yr.