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, 6MeV and 14MeV 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 reactions²⁷Al(n, p)²⁷Mg (9.6 min,E=840keV), and¹³⁷Ba(n, n)^137mBa(2.3min,E=662keV), (b) a test of the method on a composite 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.