Magnetic form factor measurements by inelastic neutron scattering

The thermal neutron cross section for scattering by crystaline-electric field (CEF) levels is d2sigma/dΩdω = A X f2(Q), where A includes physical and instrumental parameters, and f(Q) is the magnetic from facter of the ion being measured. The intensity of a neutron energy transfer peak resulting from a CEF level, measured at any Q value, is proportional to f2(Q) when all quantities in A are kept constant. The Q dependence of the form factor can therefore be derived from an energy analysis of the neutrons scattered from a powder sample, at several Q values. This method is suitable for paramagnetic ions having defined CEF levels (especially the rare earth ions). The method was utilized by the authors for measuring the form factor of Pr3+ in PrF3, Ho3+ in HoCrO3 and U4+ in UP. The measurements were carried out on the triple axis neutron spectrometer KANDI III at the NRCN. The results agree with those found in the literature. (Auth.)