The half-lives of 26mAl, 34Cl, 38mK: Precision measurements with isotope-separated samples

Abstract

The half-lives of 26mAl, 34Cl and 38mK have been measured with isotopically pure samples prepared with an on-line isotope separator. Emitted β + particles were observed with a large-solid-angle, high-efficiency, low-background gas proportional counter, from which signals were multiscaled. The counting electronics had a well-defined non-extendable dead time. Each sample decay curve was individually corrected for dead time before being summed with other accumulated data, no pile-up corrections being necessary. The analysis procedure was tested on hypothetical data. The effect of contaminant isobars on the resultant half-lives has been investigated. Our half-life results are 26m Al: 6346.2 ± 2.6 ms, 34Cl: 1527.7 ± 2.2 ms and 38mK: 924.2 ± 0.3 ms. The quote uncertainties include — for the first time — explicit provision for all possible contaminants.