New determination of the half-life of 233U

By combining different methods, all based on the measurement of the specific activity of a large number of samples from two different batches of uranium oxides, both enriched to nearly 100% 233U, a new determination of the half-life of 233U was made. The activities of the samples were determined by α counting techniques: low geometry, liquid scintillation, and 4π-proportional counting. The uranium content of the samples was determined by mass spectrometric isotope dilution techniques and by controlled potential coulometry. The half-life was measured as (1.5925+-0.0040) x105 yr. The uncertainty quoted is the over-all uncertainty at the 99.7% confidence level, taking into account both statistical and systematic effects. This result is in close agreement with the value published recently by Jaffey et al. and with the new recommended value, evaluated by Lemmel