Determination of Co-57(n, xp) cross sections using the surrogate reaction ratio method

The compound nuclei 58Co* and 61Ni* have been populated at overlapping excitation energies by transfer n + 60Ni) at Elab = 40.5 MeV, respectively. The 57Co(n, xp) cross sections in the equivalent neutron energy range of 8.6-18.8 MeV have been determined within the framework of surrogate reaction ratio method using 60Ni(n, xp) cross section values from the literature as reference. The proton decay probabilities of the compound systems have been determined by measuring evaporated protons at backward angles in coincidence with projectile-like fragments detected around the grazing angle. The measured 57Co(n, xp) cross sections are in good agreement with both the predictions of TALYS-1.8 statistical model code with default parameters using different microscopic level densities and data evaluation library JEFF-3.3 up to equivalent neutron energy approximate to 12.6 MeV, while for higher energies the measured 57Co(n, xp) cross sections are found to be consistently higher than the predictions. However, the TALYS-1.8 calculations with modified values of input potential parameters provide a reasonable reproduction of the measured 57Co(n, xp) cross sections for the entire neutron energy range. The observed discrepancies at higher energies between the experimental data and the predictions of both the JEFF-3.3 library and the TALYS-1.8 calculations with default parameters indicate the need of new evaluations for this reaction.