Browsing by Author "Schneider, Krystyna"
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Item Measurements of the effective thermal neutron absorption cross-section in multi-grain model(Institute of Nuclear Physics Polish Academy of Sciences, 2005) Drozdowicz, Krzysztof; Gabańska, Barbara; Igielski, Andrzej; Krynicka, Ewa; Schneider, Krystyna; Woźnicka, UrszulaThe effective macroscopic absorption cross-section Σaeff of thermal neutrons in a grained medium differs from the corresponding cross-section Σahom in the homogeneous medium consisting of the same components, contributing in the same amounts. The ratio of these cross-sections defines the grain parameter, G, which is a measure of heterogeneity of the system for neutron absorption. Heterogeneous models have been built as two- or three-component systems (Ag, Cu and Co3O4 grains distributed in a regular grid in Plexiglas, in various proportions between them). The effective absorption cross-section has been measured and the experimental grain parameter has been found for each model. The obtained values are in the interval 0.34 < G < 0.58, while G = 1 means the homogeneous material.