THE MULTIELEMENT POTENTIAL OF FAST-NEUTRON CYCLIC ACTIVATION-ANALYSIS

Cyclic neutron activation analysis (CNAA) has, in recent years been developed as a useful analytical tool for the assay of short-lived isotopes in single element situations. The work described in this paper investigates the potential of the technique for composite samples having a wide range of elements that - produce short-lived and long-lived isotopes on neutron irradiation. Accelerator-derived neutrons with average energies of 3 MeV, 6 MeV and 14 MeV were employed in what has been dubbed ''Fast Neutron Cyclic Neutron Activation Analysis'' (FNCAA). The approach to multi-element analysis entailed: (a) determination of cycle parameters in single element samples via the reactions Al-27(n, p)Mg-27 (9.6 min, E(gamma)=840 keV), and Ba-137(n, n'y)Ba-137m (2.3 min, E(gamma)=662 keV), (b) a test of the method on a composite E. rock sample, (c) determination of analytical sensitivities using both powdered kale and rock standards and (d) a comparison of analytical results with other techniques. The results obtained in all these measurements are presented and discussed.