The absorption statistical weights in the Advanced Reactivity-Measurement Facilities are shown to be dependent upon the slowing down power of the sample medium containing the absorber. Measurements were made for light and heavy water solutions of boric acid and 3He in the range of 0.0 to 2.0 cm2 of total sample absorption cross section with 46 ml cylindrical samples. The observed increase in absorption statistical weight with slowing down power of the sample is attributed to the coupling between the neutron scattering and absorption. A simple mathematical model is presented that accounts qualitatively for the results. Reactor calculations are in general agreement with experimental observations.nSome data are also given of samples in which the absorption was maintained constant while the slowing down power was changed, and of samples of reduced density. Further measurements are suggested to improve the interpretation of these results.nThis report sets forth in detail the work by the same authors presented in summary in Trans. Am. Nucl. Soc.
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