Half-life of ${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$

The half-life of ${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$ was determined by the relative activity method. Synthetic mixtures were prepared by using solutions of ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ and ${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$ isotopes. The $\alpha$ activity ratios and the atom ratios in these mixtures were kept close to unity by employing the double dilution technique so that these could be measured with high precision and accuracy. The $\alpha$ activity ratios were determined by $\alpha$ spectrometry on electrodeposited sources using a silicon surface barrier detector and the atom ratios were obtained by mass spectrometry. A value of 17.010±0.095 was obtained for the ${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$/${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ half-life ratio which leads to a value of 7358±42 yr for the half-life of ${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$ using the half-life of ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ as 432.6 yr. The uncertainty specified on the values is a combination of the one standard deviation on the average value and the error evaluated from the estimate on the various error components.

RADIOACTIVITY ${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$ half-life; measured: ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$/${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$ atom ratios by mass spectrometry, ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$/${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$ $\alpha$ activity ratios by $\alpha$ spectrometry.