Short-time activation analysis in geoscience

In short-time activation analysis, elements having nuclides with half-lives down to the subsecond range are analyzed by measuring their γ-ray spectra or decay curves, using in addition to a Ge(Li) or an HP-Ge detector, a Cerenkov and/or a neutron counter. To meet the demands for quantitative pulse height analysis with rapidly varying count rates and spectra, a real-time correction of counting losses was unavoidable. The principles of the 'loss-free counting system' in the virtual pulse generator version are presented. For the main elements of geochemical applications, sensitivities obtained with a prototype system are listed. Table 1 lists the total activities obtained with our system for activation analysis with short-lived nuclides up to 20 s half-life. Phosphorite analysis by γ-spectrum and decay curve analysis and analysis of NBS 1648 urban particulates by pulse activation demonstrate the usefulness of the method. (author)