Dependence of effective resonance integrals on moderator slowing down properties

Effective resonance integrals calculated by means of the usual approximations do not have the dependence on moderator slowing down properties which is shown by 'exact' calculations. In this paper a modified effective resonance integral is defined in such a way as to fit the exponential form of the resonance escape probability. Application of a generalised 'intermediate-resonance' approximation to this modified effective resonance integral shows a dependence on the slowing down properties of the moderating nuclei in good agreement with 'exact' calculations. (author)