Some statements on the detection threshold of radioactivity measuring instruments

It is shown that, from the point of view of practical radiation protection, the concept of 'detection threshold' is misleading if, when determining the detection threshold, errors of 2nd kind are not fully taken into account. An 'error of 2nd kind' is defined to be the incorrect assumption of 'no contamination' on the basis of a single measuring result which showed a net counting rate below the incertainty of the background counting rate. These errors are caused by the fact that, due to the statistical nature of the radiation process, the net counting rate of a sample, measured just once, may be below its expectation value. (orig.)