Measurement of the 230U half-life.

The 230U half-life was determined by measuring the decay curve of 230U sources by various nuclear detection techniques: α-particle counting at a defined small solid angle; 4πα+β counting with a windowless CsI sandwich spectrometer, a liquid scintillation counter and a pressurised proportional counter; gamma-ray spectrometry with a HPGe detector and nearly-2π α-particle counting with an ion-implanted silicon detector. Depending on the technique, the decay was followed for 100–200d, which is 5–10 times the 230U half-life. The measurement results of the various techniques were in good mutual agreement. The mean value, T1/2(230U)=20.23 (2)d, is lower than the literature value which is based on one measurement in 1948 and resulted in a half-life value of 20.8d without statement of uncertainty. A correction for the ingrowth of the long-lived 210Pb and its daughter products may have been overlooked in the past.