Measurement and Covariance Analysis of Californium-252 Spectrum Averaged Cross Sections

Abstract

the 252Cf fission spectrum averaged cross sections for twelve reactions have been measured relative to the cross section for the 27a1 (n, α)24Na reaction. the uncertainties of the measurements are analyzed with regard to the covariances of experimental data. it is demonstrated how to generate and combine the experimental uncertainties in the form of a variance-covariance matrix. the result of the uncertainty analysis taking account of correlations between the experimental data is given. a non-diagonal weighted least square fit has been applied to normalize the measured ratios. comparing with the standard deviation processed previously using variances only, the standard deviation obtained by the present analysis has been reduced to almost half. this may be due to the developed and improved error analysis based on the covariances between measured data. the measured values of the average cross sections presented here are compared with the calculated ones based on the energy dependent cross sections.