Spins of Neutron Resonances and the Hyperfine Coupling Constant in Gadolinium Metal

The spins of several resonances in the neutron cross section of gadolinium have been determined from measurements with polarized neutrons and polarized neuclei. Use was made of the difference in the statistical weighting factors to make the spin determinations absolute, i.e., independent of the sign of the nuclear hyperfine interaction or of any assumed directions. Assuming μ¹⁵⁵μ¹⁵⁷=+0.750, the magnitude of the nuclear magnetic hyperfine interaction is determined to be A/k=(8.0±0.8)×10^-4 ^∘{}K for Gd¹⁵⁷ and (6.0±{}0.6)×{}10^-4^∘{}K for Gd¹⁵⁵. If we assume the nuclear magnetic moment of Gd¹⁵⁷ to be -0.33 nm we obtain a hyperfine magnetic field at the nucleus, Hhf=-(3.48+0.34)×10⁵ Oe.