Methods for in-situ gamma spectrometry for the energy-selective determination of the external radiation exposure of man in selected environmental areas and at working places

Methods have been described which allow to interpret dosimetric data of gamma fields by determining the energetic distribution of quantum fluxes and to calculate the dose-rate spectra. In unfolding a high-energy scintillation gamma spectrum up to 8 MeV with the help of a response matrix, the means of linear algebra fail if the matrix is ill conditioned. In such cases, unfolding could be accomplished by means of a mathematical method based on a priori knowledge of the photon spectrum to be expected. The method was tested on in-situ gamma spectra of 16N recorded in a nuclear power plant near the primary circuit and in technical rooms, using an 1.5 x 1.5 in. NaI(Tl) scintillation detector