The 4πβ-γ coincidence method for parent-daughter decay in non-equilibrium: The measurement of the disintegration rates of 47Ca-47Sc, 45Ca

A 4πβ-γ coincidence technique, employing the 'computer discrimination' method of data collection with a pressurized gas flow proportional counter in the β-channel, is used to determine the individual activities in a mixture of 47Ca-47Sc and 45Ca, where the parent-daughter decay 47Ca-47Sc is not in equilibrium. Calibration figures for an NPL ionization chamber are derived for both 47Ca and 47Sc. The general case of a mixture of β--γ or β--emitting radionuclides is discussed and the difficulties which can result from the use of conventional methods of efficiency variation are outlined, and the advantage of using the computer discrimination method is pointed out, particularly when the shortest half-life is of the order of a day. (orig.)