Photo-neutron reaction cross-sections of Co-59 in the bremsstrahlung end-point energies of 65 and 75 MeV

Abstract

The flux-weighted average cross-sections for the Co-59(gamma, xn)Co58-55 reactions have been measured with the bremsstrahlung end-point energies of 65 and 75 MeV by using the activation method in combination with the off-line gamma-ray spectrometry. The measured cross-sections for the (gamma, n), (gamma, 2n), (gamma, 3n) and (gamma, 4n) reactions of Co-59 at 65 MeV are 15.828 +/- 0.491, 5.003 +/- 0.206, 0.408 +/- 0.047 and 0.039 +/- 0.008 mb, whereas at 75 MeV are 15.653 +/- 0.361, 4.965 +/- 0.289, 0.389 +/- 0.062 and 0.036 +/- 0.007 mb, respectively. The Co-59(gamma, xn) reaction cross-sections as a function of photon energy were also theoretically simulated by using TALYS 1.9 code. Then the flux-weighted average cross-sections at different bremsstrahlung energies were obtained from the theoretical values and the literature data at lower energy based on mono-energetic photons. The present data are measured for the first time and are found to be in good agreement with the theoretical flux-weighted average values. It was found that the Co-59(gamma, xn)Co58-55 reaction cross-sections increase from their threshold values to a certain bremsstrahlung energy. After a certain energy, the individual Co-59(gamma, xn) reaction cross-sections decrease with the increase of bremsstrahlung energy due to opening of other reaction channels. These two observations indicate the role of excitation energy and its partition in different reaction channels. All the four cobalt isotopes produced from the Co-59(gamma, xn) reactions have medical and other applications.