Looking for integral references for the fission cross sections in actinides above 1 MeV

Abstract

One of the most important sources of systematic uncertainties in the evaluation of measured cross sections is the absolute normalization of every dataset, which were often performed by measuring simultaneously the reference cross-section of the standard isotope. In other experiments the shape of the cross-section spectrum is normalized using as reference the integral value in a certain energy interval taken from an evaluated library. The choice of the energy interval used as reference has been often left up to the experimentalist criteria, leading to inconsistent normalizations and hardly assessable uncertainties. In this work the experimental datasets of the (n,f) cross section of many actinides are reviewed looking for the best suited energy interval to be recommended for renormalization purposes. Using standard integration intervals, wide enough to get very low statistical uncertainties, should improve the normalization of every experimental dataset, reducing so the associated total uncertainty when making the evaluation. A common integration range from 8 to 10 MeV is proposed for the whole set of actinides needed in fission applications. This energy range, which falls between the second and the third fission-chance thresholds, is characterized by a flat behaviour of the fission cross sections.