The analyzes chemical by neutron activation is a analytical Méthode very significant, adapted particularly well to analyze the Pureté of a sample. The method consists with to irradiate a sample by a flow of Neutron S. the various impurities contained in the sample then undergo reactions Nucléaire S which lead to the formation of Isotope S unstable. These isotopes then are identified and quantified by the study of their spectrum of rays γ.