Neutron resonance parameters and radiative capture cross sections of 147Sm and 149Sm

Neutron capture and transmission measurements have been carried out on the separated isotopes of ¹⁴⁷Sm (98.34 %) and ¹⁴⁹Sm (97.72 %) at the 55 m time-of-flight station of the Japan Atomic Energy Research Institute electron linear accelerator. Resonance energies and neutron widths for a large number of resolved resonances were determined up to 2 keV for ¹⁴⁷Sm and 520 eV for ¹⁴⁹Sm. Radiation widths for 5 resonances in ¹⁴⁷Sm + n and 7 resonances in ¹⁴⁹Sm + n were derived. The s-wave strength functions, average level spacings and average radiation widths were obtained to be: $\text{10}{}^4\text{S}{}_0\text{= 4.8 ± 0.5,}\text{D}\text{= 5.7 ± 0.5}\text{eV}$ and $\text{Γ}{}_{\mathrm{\gamma }}\text{= 69 ± 2}\text{meV for}{}^{147}\text{Sm}$; a $\text{10}{}^4\text{S}{}_0\text{= 4.6 ± 0.6,}\text{D}\text{= 2.2 ± 0.2}\text{eV}$ and $\text{Γ}{}_{\mathrm{\gamma }}\text{= 62 ± 2}\text{meV for}{}^{149}\text{Sm}$. The average capture cr sections were deduced from 3.3 to 300 keV with an estimated accuracy of 5 to 15 %. The measured capture cross sections for ¹⁴⁹Sm are largely different from the evaluated data, which are obtained based on the statistical model calculation. Possible reasons for this disagreement are discussed.