The half-lives of 42Sc, 46V, 50Mn and 54Co

As part of a broad program to determine ft values for superallowed O+ → O−β transitions, the half-lives of 42Sc, 46V, 50Mn and 54Co 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. As no exact data analysis is possible, three different procedures were compared. The most stringent method involved regression analysis where a common half-life was simultaneously fitted to the individual decay curves of hundreds of samples and their Poisson statistical weights were distorted to reflect dead-time losses.