New method to determine the decision threshold for low-level radioactivity measurements.

We discuss a new method to determine the value of a decision threshold that can be used to decide whether to choose a one-sided confidence interval or a two-sided confidence interval. The method is based on the Feldman-Cousins unified approach providing a unique confidence region for estimated parameters. We apply this method to a net count rate measurand in low-level radioactivity measurements which is physically restricted to nonnegative values. We tabulate the values of the decision threshold and detection limit of the measurand for some typical coverage probabilities. The decision threshold in this method does indeed enable a decision on whether or not the physical effect quantified by the measurand is present.