A simultaneous evaluation of some important cross sections at 14.70 MeV

A simultaneous evaluation of the 27Al(n,α), 56Fe(n,p), 63Cu(n,2n), 197Au(n,2n), 93Nb(n,2n), 32S(n,p) and 1H(n,n) cross sections at an energy of 14.70 MeV has yielded a consistent set with uncertainties (lσ) of 0.6-2.8%. The large number of experimental activation results included were all considered as ratios between cross sections, and the method of weighted least-squares was used in the evaluation, the results being normalized to the associated particle measurements. The results have been compared with several other evaluations, and are mostly in agreement within the errors. It was found that the ENDF/B5 ratio of the two most commonly used standard cross sections, 27Al(n,α) and 56Fe(n,p), was 7.5% higher than our ratio. The 65Cu(n,2n) activation cross section, which has often been used as a reference, cannot be determined to better than about 3% until the 64Cu decay scheme is better known than at present. (author)