RESUMO
The procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN for the primary standardization of a (243Am + 239Np) solution, in secular equilibrium, is described. The measurement was carried out in a 4π(PC) (α,ß)-γ coincidence system. The total activity per unit mass of the solution was determined by the extrapolation technique, using a software coincidence counting systsem. The extrapolation curves were compared with Monte Carlo calculations by means of Code ESQUEMA, used in previous works, which, was improved and applied in order to calculate the alpha, beta, gamma, X-rays and coincidence spectra.
RESUMO
The procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN-CNEN/SP, in São Paulo, for the primary standardization of 166Ho is described. The activity of 166Ho was determined by the efficiency extrapolation technique applied to a 4πß(PC)-γ coincidence system using a gas flow proportional counter in 4π geometry coupled to a 76 × 76 mm NaI(Tl) crystal. The results for the γ-rays intensities at 80.57 and 1379.45 keV were 0.0651(11) and 0.00904(11), respectively.