NEUTRON ACTIVATION ANALYSIS AS A TOOL FOR THE STUDY OF EXOGENOUS INCLUSIONS IN FERROUS MATERIALS: A PROGRESS REPORT,

La and Sm are useful in the cool labelling of refractory materials. The feasibility of direct analysis of La and Sm traces strongly depends on the composition of ferrous materials to be tested the sensitivity was found to range between 0.015 and 5 micro for the adopted experimental conditions. In any case extremely low sensitivities better than 0.001 micro g are reached by employing a destructive technique, which, on the other hand, is always required when the exogenoustotal inclusion ratio has to be evaluated preliminary extraction of the inclusions from the sample. A destructive activation analysis makes possible the study an doublelabelled ferrous materials by means of single determinations La and Sm traces can be simultaneously determined with good precision even when their concentrations are quite different from each other. Both destructive and direct determinations may be performed in a relatively short time v.z. a ten samples can be analyzed without difficulty in a 2-day delay, including irradiation, cooling, chemical separation and counting the accuracy of the method may be kept within 15. Author