The (n,2n) isomeric cross section ratios and the (n,2n) excitation function for 197Au

The (n,2n) isomeric state/ground state cross section ratio sigmasub(m)/sigmasub(g) and the (n,2n) isomeric state cross section sigmasub(m) of 197Au have been measured in the energy range 14.2-18.2 MeV by activation techniques using a Ge(Li) detector gamma-ray spectrometer. Neutrons were produced with the 3H(d,n)4He reaction. The cross section ratios were determined from least squares fits to the ground state gamma activity of 196Au(Esub(γ)=356 keV). The absolute isomeric cross sections were determined by measuring the gamma activity of the metastable state in 196Au(Esub(γ)=148 and 188 keV) using the mixed-power method with 27Al(n,α)24Na as the monitor reaction. The measured cross section ratios and the isomeric cross sections were found respectively to be (0.075+-0.003) and (152+-11)mb at (14.2+-0.2)MeV, (0.078+-0.003) and (161+-11)mb at (15.2+-0.2)MeV, (0.096+-0.007) and (185+-13)mb at (16.2+-0.2)MeV, (0.122+-0.02) and (202+-14)mb at (17.2+-0.2)MeV, and (0.124+-0.003) and (185+-13)mb at ((18.2+-0.2)MeV. The isomeric cross section at 14.2 MeV was also measured using associated particle techniques for monitoring the neutron flux. The average cross section for three associated particle activations was (155+-8)mb. (orig.)