Coherent Neutron Scattering by Cobalt with Nuclear Polarization

The polarized-neutron diffraction technique has been used to determine the modification of coherent scattering with nuclear polarization in cobalt. This was studied in two Bragg reflections, (220) and (140), from a crystal of hexagonal cobalt at temperatures as low as 2.23^∘{}K, with nuclear polarization being developed by hyperfine field interaction in the ferromagnetic element. From these observations, the spin-state scattering amplitudes b₊ and b_-, corresponding to neutron-nucleus compound states of spin I+1/2 and I-1/2, respectively, have been determined as (-0.380±{}0.054)×{}10^-12 and (+1.060±{}0.070)×{}10^-12 cm. These values are found to be consistent with the coherent scattering amplitude as obtained in unpolarized-neutron-unpolarized-nucleus studies, and with the known neutron resonance level structure in cobalt.