METHOD FOR SEPARATING THE NUCLEAR AND MAGNETIC CONTRIBUTIONS OF THE SMALL-ANGLE SCATTERING OF UNPOLARIZED NEUTRONS ON DISPERSE COLLOIDAL SYSTEMS WITH MAGNETIC PROPERTIES BY APPLYING THE PHASE CONTRAST VARIATION METHOD

摘要

The invention relates to a method for separating the nuclear and magnetic contributions of the differential cross section of scattering at small angles of the unpolarized neutrons on disperse colloidal systems with magnetic properties, by applying the phase contrast variation method. The essential elements of the method are the use of the controlled deuteration of the solvent, in the sense of decreasing to annulment of the difference between the nuclear scattering density of the magnetic colloidal particles and the scattering density of the solvent and the identification of the concentration, x, of the volume fraction of the deuterated substance in the carrier fluid made of H-D compound (deuterated substance - same non-deuterated substance) for which the minimum differential scattering cross section is due only to the magnetic component, the nuclear component becoming null due to the equalization of the nuclear scattering densities of the magnetic particles and of the solvent in the investigated sample. Compared to the methods currently used, this method has the advantage of performing the separation of the components of the differential scattering cross sections of the neutrons without inducing alterations to the investigated system by applying an external magnetic field. The effected isotopic substitution provides the possibility of a direct and simultaneous measurement of both physical and magnetic size or size distribution of the nanoparticles.