Calculation of primary nuclear interferences occurring in neutron activation analysis with a slowpoke reactor

The cross-sections for (n, p) and (n, α) reactions which may interfere with (n, γ) reactions used in thermal neutron activation analysis have been calculated systematically using an empirical formula in conjunction with published σ-values. The interference factors (IF) have been subsequently calculated for flux conditions that prevail in a SLOWPOKE II reactor and both cross sections and interference factors have been listed in a tabulated form. The significance and usefulness of IF's thus obtained is discussed from the standpoint of trace analysis. For a number of low-Z matrices, their magnitude is such that the measurement of certain constituents at the ppm level by instrumental analysis is rendered virtually impossible, as for the following matrix—trace element pairs=Al/Mg, Na/Al, P/Si, S/P and Cl/S. For higher Z elements, interferences can be neglected in most instances.