The calculation of neutron yields in mixtures and compounds from the thick target (α,n) yields in the separate constituents

A simple relation is derived between the thick target yield of neutrons produced following (α,n) reactions in compounds or homogeneous mixtures and the yields in the separate constituents. It is necessary to assume that the Bragg law of additivity of stopping powers holds for the compound and to make the approximation that the stopping powers of all materials vary with energy in the same way, apart from constant factors. The range of validity of the second hypothesis is examined in some detail. It is shown to be far superior to the approximation of a stopping power independent of energy. (author)