Open Access
ND 2007
Article Number 326
Number of page(s) 4
Section Standard cross sections
Published online 17 June 2008
International Conference on Nuclear Data for Science and Technology 2007
DOI: 10.1051/ndata:07346

Uncertainty justification of neutron cross section standards

Evgeny Gai and Vladimir Pronyaev

Institute of Physics and Power Engineering, Bondarenko sq. 1, 249033 Obninsk, Kaluga reg., Russia

Published online: 21 May 2008

The existence of general measures for the covariance matrices of the evaluated data uncertainties obtained in different model and non-model least-squares fits of the same experimental data is considered. It is shown that some quantities (called measures here) calculated from the elements of covariance matrices are exactly and others are approximately conserved quantities independent from the model used in the fit. The use of these measures allows a simple comparison of uncertainties obtained in different evaluations of the same cross sections. The measures were used for the justification of the uncertainties of the neutron cross section standards evaluated in least-squares fits of a bulk volume of the experimental data. It is shown that the uncertainties obtained in the standards evaluation are realistic and determined completely by the uncertainties of the experimental data when taking into account all known correlations between the different experiments.

© CEA 2008