Semi-empirical systematics of (n, p) reaction cross sections for 14.5 MeV neutrons

A new semi-empirical formula for the calculation of the (n, p) cross section at 14.5 MeV neutron energy is obtained. Derived from the evaporation statistical model, the new formula includes five parameters and shows for the first time a strong dependence of the (n, p) cross section on terms of the parameter (2Z−1)/A. Fitting this formula to the existing cross section data on 161 nuclei with 40≤A≤209, the adjustable parameters have been determined and the systematics of the (n, p) reaction have been studied. The predictions of this formula are compared with those of the existing formulae and with the experimental data. The formula with five parameters is found to give a better fit to the data than the previous comparable formulae.