Half-life ofAm243

The half-life of /sup 243/Am was determined by the relative activity method. Synthetic mixtures were prepared by using solutions of /sup 241/Am and /sup 243/Am isotopes. The ..cap 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 ..cap alpha.. activity ratios were determined by ..cap 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 /sup 243/Am//sup 241/Am half-life ratio which leads to a value of 7358 +- 42 yr for the half-life of /sup 243/Am using the half-life of /sup 241/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.