Artur W. Carbonari and Brigitte R.S. Pecequilo

Nuclear Physics Division, Instituto de Pesquisas Energéticas e Nucleares
Comissão Nacional de Energia Nuclear
Caixa Postal 11049 - Pinheiros
05499 São Paulo - SP, Brasil

In the present experiment we have measured the gamma-ray spectrum of thermal neutron capture on 58Ni in the energy range of 3.7 to 9.3 MeV. The experiment was carried out at the tangential irradiation facility of the IEA-R1 research reactor at São Paulo. The gamma-rays were detected by a Ge(Li)-NaI(Tl) pair spectrometer. The partial cross sections for nineteen primary gamma-ray transitions have been calculated and, by summing all of them, we have determined the total thermal neutron capture cross section for the 58Ni(n,γ)59Ni reaction. The resultant value is 4.52 ± 0.10b. We have also calculated the theoretical value of the partial cross sections for eleven primary E1 transitions based on the direct capture model and compared with the experimental results.