DeterminingPa234(n,f) cross sections using the surrogate method

Abstract

The fission decay probabilities of the $^{235}\mathrm{Pa}$ and $^{236}\mathrm{U}$ compound nuclei produced in a single experiment in $^{232}\mathrm{Th}$($^{7}\mathrm{Li}$, $\ensuremath{\alpha}f$)$^{235}\mathrm{Pa}$ and $^{232}\mathrm{Th}$($^{7}\mathrm{Li}$, $tf$)$^{236}\mathrm{U}$ transfer induced fission reaction channels, have been measured at ${E}_{\mathrm{lab}}=39.5$ MeV in the excitation energy range of 14--20 MeV. The $^{234}\mathrm{Pa}$(n, f) cross sections are then deduced from the measured fission decay probability ratios of $^{235}\mathrm{Pa}$ and $^{236}\mathrm{U}$ compound systems in the equivalent neutron energy range of 8--14 MeV within the framework of the hybrid surrogate ratio method, considering the well-measured $^{235}\mathrm{U}$(n, f) cross sections as the reference. The experimental data on $^{234}\mathrm{Pa}$(n, f) cross sections have been compared with the calculated fission cross sections using empire-3.1 code with the fission barrier height values obtained from barrier formula (BF) as well as ripl-3 [24]. The present experimental results are found to be in very good agreement with the empire-3.1 predictions for the fission barrier heights predicted by the BF.