Nuclear data standardization in absolute NAA: Practice in Yugoslavia

In absolute and single-comparator (e.g. k0) methods of activation analysis with reactor neutrons (NAA) the accuracy of nuclear data used is of primarily importance. So as to avoid systematic errors, cooperative, but independent experiment work of several scientific institutions is essential in this respect. Jozef Stefan Institute, Ljubljana and Faculty of Sciences, Titograd, Yugoslavia are engaged in determining the relevant nuclear constants for the k0-NAA method, together with the National Institute of Standards and Technology, Gaithersburg, MD, USA and the Institute for Nuclear Sciences, Gent, Belgium. The latter constants, characterizing (n,gamma) reactions are (1) k0-factors, compound nuclear constants, including gamma-line intensities, thermal cross sections and isotopic abundances of both (n,gamma) reaction of interest and of the comparator reaction; (2) Q0-factors, which are resonance integral to thermal (2,200 ms-1) cross section ratios and (3) bar Er-values, the effective resonance energies, which account for the deviation of the resonance integrals in 'non-ideal' (i.e. non-1/E) epithermal neutron spectrum distribution