Studies of (n,t) reactions on light nuclei

Cross Sections were measured with uncertainties of 13 to 21% for the reactions 9Be(n,t)L7Li, 10B(n,t)2α and 14N(n,t)12C over various energy ranges. Irradiations were performed with thermal neutrons and neutrons produced via the reactions 2H(d,n)3He and 9Be(d,n)10B. The tritium produced and accumulated in the irradiated samples was separated by vacuum extraction and measured in the gas phase using anticoincidence β- counting. The residual tritium content was determined for the enriched 10B and AlN samples. The characteristics of tritium diffusion in B4C were studied by high-temperature release experiments. The Li impurity in the AlN sample was determined via neutron activation analysis. The average 9Be(n,t)7Li cross sections lie between 3 and 14 mb for break-up neutrons produced by 17.5 to 31.0 MeV deuterons on a thick Be target. A comparison of the measured data with the values deduced from differential data and neutron spectral distributions shows agreement within ± 21%. The 10B(n,t)2α cross sections in the neutron energy range of 0.025 eV to 10.6 MeV lie between 12 and 215 mb (with the maximum at about 5.5 MeV). The 14N(n,t)12C cross sections in the neutron energy range of 5.0 to 10.6 MeV lie between 11 and 30 mb. The excitation function shows a fluctuation which is attributed to the decay properties of the compound nucleus 15N. Detailed Hauser-Feshbach calculations show that the statistical model cannot satisfactorily describe the (n,t) cross section on light nuclei. (orig.)