Systematics for (n, α) excitation functions in the neutron energy between 13.3 and 15.0 MeV

A systematics of (n, α) partial excitation functions in the neutron energy between 13.3 and 15.0 MeV was studied on the basis of experimental data measured by Nagoya University and FNS groups (Japan Atomic Energy Research Institute). The empirical formulae of cross sections at 14.0 MeV (σ14) and relative slopes of excitation functions (S) were deduced. The empirical formula of relative slope was expressed as a function of effective threshold energy Eth + Vα, where Eth is threshold energy, and Vα is the coulomb barrier for the α-particle emitted from the compound nucleus. The empirical formula of σ14 was expressed by a simple formula with 2-fitting-parameters. By using the proposed empirical formulae, the partial excitation functions between 13 and 15 MeV were reproduced. Comparing the experimental data with the calculated excitation functions, we concluded that the accuracy of the proposed empirical formulae was ± 30%. (Author)