Neutron-depolarization theory in particulate media

Abstract

Neutron-depolarization (ND) theory in particulate media is discussed. The relations between the correlation matrix \ensuremath{\omega}, derived from a neutron-depolarization experiment, and parameters describing the micromagnetic state of a particulate medium are derived and discussed extensively. The latter involves the individual particles, magnetic interparticle correlations as a result of particle interactions or particle orientational correlations, density variations within the medium, and variations in the neutron transmission length over the cross section of the medium. These theoretical relations have been used to interpret some of the results of ND measurements on a ${\mathrm{CrO}}_{2}$ pigment. It is shown that the neutron-depolarization technique yields relevant quantitative information about the micromagnetic state of particulate media.