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 $I+\frac{1}{2}$ and $I-\frac{1}{2}$, respectively, have been determined as (-0.380±0.054)×${10}^{-12\mathrm{}}$ and (+1.060±0.070)×${10}^{-12\mathrm{}}$ 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.