NMR/ON of ⁶⁰Co Experiments on the Neutron Activated Fe-Co Alloy

Abstract

The irradiation by thermal neutrons is a commonly used procedure for the preparation of radioactive samples for low-temperature nuclear orientation (LTNO) experiments. Such an irradiation is a potential source of irradiation damage. The ferromagnetic alloy Fe+0.5 Co was selected for this kind of radiation damage study by LTNO and the nuclear magnetic resonance of oriented nuclei (NMR/ON), respectively. It was found by LTNO that in an as-irradiated sample, smaller amount of ⁶⁰Co nuclei is subject to regular hyperfine field B _hf=29.01 T in comparison with the annealed sample. The same LTNO single resonance line on the frequency f=165.6(2) MHz was observed with both as-irradiated and annealed samples, respectively. The resonant destruction of γ-ray anisotropy is significantly smaller in as-irradiated sample and higher rf field is to be used to obtain a sizable NMR/ON effect. The experimental data indicates a great spread of hyperfine field values in non-regular positions of ⁶⁰Co nuclei without contribution to the NMR/ON.