Determination of particle mean free path beta decay in the particulate material

We developed a method for the experimental determination of the mean free path of the particles of β-decay in powder materials, to improve the accuracy of calculations when selecting materials for screens. Error in the calculation materials of complex chemical composition by empirical formulas reaches 30 %. For the study, we took a powder PT-NA-01. Selection is based on the fact that the powder is composed of two elements, the mean free path of the electrons can be calculated according to the formulas with high accuracy. Morphological study of the powder showed that the particles are in the shape of fragments and 87 % of their size in the range of 40 to 80 microns. The weight ratio of lacquer in a powder sample was determined experimentally. The best was the composition comprising 3 % lacquer in the dry residue. It has been found that the polymerization of lacquer loses 50 % of the mass. Investigation of factors of manufacturing process of samples showed that the optimal compression pressure of 6 t / cm 2, and the density of the samples do not exceed 65 %. The pressure is chosen depending on the strength properties of the briquettes. We used radiation isotope St-Y with intensity 2,7E + 05 pulses / sec. The proportion of radiation absorption in the binder was investigated on samples of lacquer. The measurements showed that its attenuation coefficient is 1,26 ± 3 % for the thickness of 0.08 cm with a density of 1,07-1,18 g / cm 3. In these studies, the contribution of the binder can be neglected because its content does not exceed 3 % by weight of filler. It was found that dependence of intensity on the thickness of the sample, the value of the extrapolated path of the electrons is equal to (0,21 ± 0,04) cm, it belongs to the region of the confidence interval, the values calculated by empirical formulas 0.14 cm divided by the fill factor was equal to 0.65, the calculation accuracy of 15 %. To increase the fill factor and reduce the thickness of the lacquer on the particles, we examined the effect of the viscosity of the lacquer on the density of the sample. The distance between the particles in the samples with lacquer, which dissolved 1:1 by weight with ethanol is much smaller. The fill factor of these samples reached 0.88, and extrapolated path - (0,16 ± 0,02) cm. The accuracy of calculation of the mean free path of the proposed method does not exceed 10 % in this material.