On the Methodology to Calculate the Covariance of Estimated Resonance Parameters

Journal Article · Thu Jan 15 04:00:00 EST 2015 · Nuclear Data Sheets

DOI:https://doi.org/10.1016/J.NDS.2014.12.030· OSTI ID:22436778

Becker, B.; Kopecky, S.

Principles to determine resonance parameters and their covariance from experimental data are discussed. Different methods to propagate the covariance of experimental parameters are compared. A full Bayesian statistical analysis reveals that the level to which the initial uncertainty of the experimental parameters propagates, strongly depends on the experimental conditions. For high precision data the initial uncertainties of experimental parameters, like a normalization factor, has almost no impact on the covariance of the parameters in case of thick sample measurements and conventional uncertainty propagation or full Bayesian analysis. The covariances derived from a full Bayesian analysis and least-squares fit are derived under the condition that the model describing the experimental observables is perfect. When the quality of the model can not be verified a more conservative method based on a renormalization of the covariance matrix is recommended to propagate fully the uncertainty of experimental systematic effects. Finally, neutron resonance transmission analysis is proposed as an accurate method to validate evaluated data libraries in the resolved resonance region.

• OSTI ID: 22436778
• Journal Information: Nuclear Data Sheets, Journal Name: Nuclear Data Sheets Vol. 123; ISSN NDTSBA; ISSN 0090-3752
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
DATA COVARIANCES
EVALUATED DATA
EXPERIMENT RESULTS
EXPERIMENTAL DATA
LEAST SQUARE FIT
NUCLEAR DATA COLLECTIONS
RENORMALIZATION
RESONANCE