Spin and resonance parameters of the 3.90 eV neutron resonance and magnetic hyperfine constant in 169Tm

Abstract The spin of the 3.9 eV neutron resonance in 169 Tm was determined to be J = I+ 1 2 = 1 by measuring the transmission of polarized monoenergetic neutrons through a polarized target. The resonance parameters redetermined from new total cross-section measurements are E 0 = 3.90±0.02 eV, Γ γ = 0.099±0.003 eV and Γ n = 0.0081±0.002 eV. The variation of nuclear polarization with temperature yields the value for the magnetic hyperfine constant A / k = 0.206±0.014° K in the non-saturated ferromagnetic polycrystalline metal.