CODE | NUCLIDE | ORIGINAL DATA TAKEN FROM | MODIFICATION | ADDITIONAL FILE MODIFICATIONS | ORIGINAL DATA TAKEN FROM | MODIFICATION | ADDITIONAL FILE MODIFICATIONS | COMMENTS |
1082206 | 082_Pb_206 | JEFF-3.1 | Covariances - BNL, July, 2011: Covariances were adopted from COMMARA-2.0, where BNL performed a new evaluation of covariances for a set of four Pb isotopes in the full energy range in 2010. The thermal and resolved resonance region made use of the covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. We note that the resonance region for Pb isotopes extends to very high energies. Elastic scattering uncertainty in the resonance region was largely determined by potential scattering contribution via the uncertainty of the scattering radius R'. In the fast neutron region up to 20 MeV covariance estimates were produced using the nuclear reaction code EMPIRE and the Bayesian code KALMAN. The KALMAN code along with selected experimental data was used to determine the correlation matrix of the model parameters. Furthermore, additional parameters scaling total and absorption cross sections were included to prevent the unrealistic drop in the cross-section uncertainties and, in some instances, to cover spread of the experimental data. For all Pb isotopes, the elastic cross-section uncertainties were computed as difference of total and absorption reaction channel. |