Primary standardization and Monte Carlo modeling of (Am + Np) by means of a 4π(PC)-γ coincidence counting system.

The procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN for the primary standardization of a (Am + Np) solution, in secular equilibrium, is described. The measurement was carried out in a 4π(PC) (α,β)-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.