Detailed analysis of (n,p) and (n,α) cross sections in the EAF-2007 and TALYS-generated libraries

Large cross section libraries, such as EAF-2007 used for activation calculations, need to be validated. A traditional approach employs simple systematic formulae based on experimental data and derived at energies such as 14.5 MeV. Such systematics are also used for renormalization of cross sections during library preparation. This approach is gradually being replaced by using results of sophisticated nuclear model calculations. As the energy range of EAF libraries has expanded from 20 to 60 MeV an additional approach is required and the method of ‘statistical analysis of cross sections’ (SACS) has proved to be useful. SACS analyses are carried out for the important charged particle reactions (n,p) and (n,α) in the EAF-2007 and TALYS-6 libraries. TALYS-6 is a calculational library generated by the TALYS model code Version 0.72. SACS considers various reaction statistics such as σmax, Emax and Δ1/2 and plots scatter plots against a parameter such as the asymmetry (s). Trend lines using simple algebraic formulae can be fitted to the data and points discrepant from the trends correspond to reactions that require improvement. A new observation is a ‘step’ in the Δ1/2(s) plot for (n,p) reactions and this has been interpreted as due to competition between (n,p) and (n,n′p) reaction channels. Equations for the various trend curves for EAF-2007 are given.