[en] The described procedure is purely instrumental. The aim is to determine efficiently the elemental composition of geological materials by neutron activation, using short-lived isotopes. The procedure requires the use of a gamma-spectrometric system fitted with a real time correction module for the counting losses and the quasi absolute k₀-method. Consequently, the two constraints inherent in the analysis of short-lived isotopes, i.e. decreasing dead time counting and relative standardization were overcome. (author) 16 refs.; 4 figs.; 3 tabs