The thermal neutron capture cross-sections and resonance capture integrals of 44Ca, 62Ni, 168Yb, 174Yb, 169Tm, and 203Tl

Abstract

The effective neutron capture cross-sections of the isotopes 44Ca, 62Ni, 168Yb, 174Yb, 169Tm and 203Tl have been measured by the activation method. By irradiating samples with and without cadmium covers, and by assuming a 1/v dependence in the sub-cadmium region, the 2200 m/sec cross-sections and the resonance integrals have been calculated using the Westcott convention. The values for σ o are 44Ca 0·88±0·01 barns, 62Ni 14·2±0·3 barns, 168Yb 3470±50 barns, 174Yb 141±2 barns, 169Tm 106±3 barns and 203Tl 8·9±0·4 barns. The resonance integrals (Σ) are 44Ca 0·56±0·01 e barns, 62Ni 9·6±3·5 barns, 168Yb 21000±4200 barns, 174Yb 68·6±7·2 barns 169Tm 2240±130 barns and 203Tl 349±17 barns. All measurements are relative to a 59Co cross-section of 37·5 barns and a 59Co resonance integral of 69·9 barns. Errors are experimental and quoted at the 95 per cent confidence level.