Thermal-Neutron Capture Cross Section and Resonance Integral of Americium-241

The thermal-neutron capture cross section (σ_0;g) and the resonance integral (I _0,g) leading to the ground state of 242Am were measured by an activation method for neutron capture by²⁴¹ Am. A method with gadolinium, which was similar to the cadmium difference method, was used to measure the cross section σ_0;g with attention to resonances of²⁴¹ Am. Americium chloride samples containing²⁴¹ Am radioisotope were irradiated for 68 h in the long-irradiation plug of the Kyoto University Research Reactor, KUR. Wires of Co/Al and Au/Al alloys were used as monitors to determine thermal-neutron fluxes and epithermal Westcott's indexes at the irradiation positions. An α-ray spectrometer was used to measure the activity ratios of²⁴² Cm to²⁴¹ Am. On the basis of Westcott's convention, the σ_0;g and I _0,g values were determined as 628 ± 22 b and 3:5 ± 0:3 kb, respectively.