Values of the reduced activation resonance integral relative to the thermal cross section I′/σ0 of 74Ge and 76Ge were determined relative to gold by measuring cadmium ratios in a reactor spectrum.A lithium-drifted germanium γ-ray spectrometer was used to resolve the activities of the samples.The results for 74Ge are I′/σ0 = 1.514 ± 0.031 and I′ = 0.681 ± 0.123 b with an assumed σ0 = 0.45 ± 0.08 b; for 76GeI′/σ0 = 12.00 ± 0.16 and I′ = 1.992 ± 0.359 with an assumed σ0 = 0.166 ± 0.030 b.The values obtained for I′ are in serious disagreement with the values calculated with neutron resonance parameters and confirm previous results obtained in similar keV average resonance spacing isotopes.Due to this fact a careful evaluation of the keV neutron radiative capture cross section and resonance integral for 74Ge was undertaken.The evaluation and comparison with the experimental value of the resonance integral shows first that for nuclides with an average resonance spacing of keV the unresolved resonance integral has been seriously underestimated in many evaluations, and second that between 10 and 100 keV, resonance integrals calculated with smooth low resolution activation cross sections give a better calculation of neutron captures than that obtained with neutron resonance parameters.
Neutron resonance parameters and radiative capture cross sections of 147Sm and 149Sm
