The total neutron cross-section of Ra226☆

Abstract The total cross-section of radium has been measured with a mechanical velocity selector between 0·22 and 50 eV. A resonance is found at E 0 = 0537 ± 0·006 eV whose parameters, calculated with allowance for Doppler broadening and instrumental resolution, are σ 0 = 3,600 ± 150 barns, Γ = 0029 ± 0.001 eV, and Γ n = 2·1 ± 0·1 × 10 −5 eV.