DECISION LIMIT, DETECTION LIMIT, AND CONFIDENCE-INTERVAL IN GENERAL NUCLEAR RADIATION SPECTROMETRY

A procedure for the general non-linear unfolding of nuclear radiation spectra and for calculating the decision limit, the detection limit and a confidence interval of a spectrum parameter, for example the net intensity of a spectral line, is described. The procedure will serve as the theoretical basis of an envisaged German standard in the DIN 25482 series. It essentially consists in a non-linear adjustment calculation, for example using the least-squares method takes into account the uncertainties of all quantities according to the DIN 1319-4 standard, and is carried out in four steps: I) setting-up of the spectrum unfolding model, 2) preparation of the input data, 3) unfolding of the spectrum 4) determination of the decision limit, the detection limit, and the confidence interval. The setting-up of the model is demonstrated by examples from the spectrometry of alpha and gamma radiation and from the monitoring of radioactive emissions. The procedure is applied to linear unfolding to show how it is used.