Half-life determination of 213Bi and 209Pb by means of Cherenkov counting and detection with a NaI detector

An 225Ac source was prepared and combined with a dedicated setup to collect recoil atoms which are ejected as a consequence of alpha decay. Some targets were made of acrylic glass and were then placed in custom-built triple-to-double coincidence ratio (TDCR) counters to measure the Cherenkov counting rates as a function of time. Half-lives of 213Bi and 209Pb were derived from the data. In addition, polyethylene films were used as targets to collect recoil atoms. These films were then measured in a well-type NaI detector to detect gamma rays. The analysis of the data yielded an independent result for the half-life of 213Bi. Combining the results of both measurement techniques, T1/2(213Bi) = (45.60 ± 0.09) min was obtained as a final value for the half-life of 213Bi. The half-life of 209Pb was found to be T1/2(209Pb) = (195.1 ± 2.6) min. •The half-lives of 213Bi and 209Pb were measured using two methods.•Cherenkov counting and gamma spectroscopy with a NaI detector were used.•Separation of 213Bi from 225Ac decay series was performed by collection of recoil atoms.•Cherenkov samples were prepared from clear acrylic glass.•Results agree well with previous literature data.