COVARIANCE MATRICES EVALUATED BY DIFFERENT METHODS FOR SOME NEUTRON-DOSIMETER REACTIONS
Department of Energy Conversion Engineering,
Kyushu University, Kasuga, Fukuoka 816, Japan
Covariance matrices between neutron-induced activation cross sections depends strongly on an evaluation method. The activation cross sections for neutron dosimeter can be evaluated from experimental data. In order to obtain covariances, differential and integral experiments are used in the evaluation. Correlation is localized in the limited energy regions where the measurements are abundant. In another way, the covariance matrices can be also evaluated by nuclear reaction model calculation in which are used the parameters estimated from experiments. Correlation is not localized but distributed over whole energy regions. These differences influence neutron spectra to be measured in unfolding from dosimeter activities.
KEYWORDS: Dosimeter, Covariance, Nuclear Parameters, Hauser-Feshbach model