The influence of background neutrons on (n,γ) activation measurements in the neutron energy region 2.0–7.7 MeV

Sources of errors in the measurement of MeV neutron capture cross sections with the activation technique have been investigated using the reaction 115In(n,γ) 116mIn. The main problems are caused by low-energy background neutrons produced by charged-particle reactions (e.g.(p,n) and (d,n) reactions) in the target material and secondary neutrons from nonelastic reactions (e.g.(n,n′) and (n,np) reactions) in the sample and surrounding materials. Low-mass target-sample assemblies have been constructed to reduce the influence of secondary neutrons. Methods to correct for the background neutrons have been developed and applied to cross-section measurements for the reaction 115In(n,γ)116mIn in the neutron energy range 2.0–7.7 MeV. The cross section values are significantly lower than previous results.