Accuracy increasing in the nuclear-physical analysis of mineral raw materials of heterogeneous composition

In the practice of the instrumental nuclear-physical analysis, because of the simple realization and very deep research, the gamma-albedo method is widely used. When realizing the gamma-albedo method the problem of macro-heterogeneity account arises. The intensity of the gamma-radiation scattered by the analyzed medium is in general case a function of material and granulometric composition. Macro-heterogeneity effect on the intensity value of scattered gamma-radiation can be considered from the two points of view. On one hand, the intensity of scattered by the heterogeneous medium gamma-radiation a function of the particle sizes and differential function of their distribution. Variations of the particle sizes non-correlated with the defined component content lead to the dispersion of the intensity value. On the other hand, the heterogeneous medium is represented by the system of randomly distributed particles of the defined component and filler and this leads to the static fluctuation of the defined component content in the studied medium. The total methodological error at the expense of macro- heterogeneity are presented as a result of the simultaneous action of the above-mentioned factors. Thus, the problem of estimation of the total error at the expense of macro heterogeneity reduces to the defining of the gamma-albedo method sensitivity to the defined component content and to the particle sizes, taking into account the analytical expression presence, which describes the scattered gamma-radiation dependence upon the material and granulometric composition of the analyzed heterogeneous object. Mathematical modeling of the total error minimization process of the gamma-albedo analysis at the expense of heterogeneity has been carried out on the basis of approximation of heterogeneous media by the set of flat and parallel layers of variable height and single gamma-radiation interaction approach. The results obtained show that for the methodical error minimization in the analysis of heterogeneous raw material by the gamma-albedo method it's necessary to optimize the primary gamma-radiation energy choose depending on the material composition of the raw material, its granulometric composition and to reach the maximal presentability of the analysis. For this a method has been suggested which allows to increase substantially the effective study surface without increasing the analyzed object size. The essence of the method consists in the rotation of the object around its axis relatively to the detector reciprocating parallel to the sample in the process of measuring. The optimal laws of the detector motion and the sample rotation provide for the equal presentability of each unit study surface. The experimental approving of the suggested method showed that the optimization of the methodical and geometrical control parameters in the dynamic measuring conditions allow to increase the accuracy of the analysis of disperse raw materials more that twice as large