Emission probabilities of the main γ-rays of 237Np in equilibrium with 233Pa

Due to the needs in environment monitoring and nuclear waste survey, there has been increasing interest over recent years for measuring the activity of 237Np. Thus, the EUROMET project No. 416 has been proposed by NPL, in order to improve as well as possible the knowledge of the decay scheme of this radionuclide. In order to achieve this objective, the emission probabilities of the main gamma-rays following the decay of 237Np in equilibrium with its daughter 233Pa, have been precisely measured, using calibrated Ge-HP detectors and sources for which the activity has been determined from absolute measurement. The obtained results, the main instrumentation characteristics, details of the experimental procedure, are presented and discussed in this paper.