The coherent neutron scattering cross section of Ho as determined from neutron diffraction measurements on ${\mathrm{Ho}}_2$${\mathrm{O}}_3$ is found to be (9.1±0.5) b with amplitude of positive phase. The total nuclear scattering cross section is estimated to be about 13 b. The magnitude and angular dependence of the differential cross section for paramagnetic scattering by the trivalent holmium ion in ${\mathrm{Ho}}_2$${\mathrm{O}}_3$ have been measured at room temperature. For small scattering angles the observed cross section is equal, within experimental error, to that calculated for the free-ion moment, i.e., 10.6 Bohr magnetons, and the angular dependence of the differential scattering cross section reflects the full contribution of the orbital as well as of the spin contribution to the total moment of the ion.

• Received 5 December 1957

DOI:https://doi.org/10.1103/PhysRev.110.37