tailieunhanh - Estimating model bias over the complete nuclide chart with sparse Gaussian processes at the example of INCL/ABLA and double-differential neutron spectra

This paper shows how a sparse approximation to Gaussian processes can be used to estimate the model bias over the complete nuclide chart at the example of inclusive double-differential neutron spectra for incident protons above 100 MeV. | Estimating model bias over the complete nuclide chart with sparse Gaussian processes at the example of INCL ABLA and double-differential neutron spectra EPJ Nuclear Sci. Technol. 4 33 2018 Nuclear Sciences G. Schnabel published by EDP Sciences 2018 amp Technologies https epjn 2018013 Available online at https REGULAR ARTICLE Estimating model bias over the complete nuclide chart with sparse Gaussian processes at the example of INCL ABLA and double-differential neutron spectra Georg Schnabel Irfu CEA Université Paris-Saclay 91191 Gif-sur-Yvette France Received 7 November 2017 Received in final form 2 February 2018 Accepted 4 May 2018 Abstract. Predictions of nuclear models guide the design of nuclear facilities to ensure their safe and efficient operation. Because nuclear models often do not perfectly reproduce available experimental data decisions based on their predictions may not be optimal. Awareness about systematic deviations between models and experimental data helps to alleviate this problem. This paper shows how a sparse approximation to Gaussian processes can be used to estimate the model bias over the complete nuclide chart at the example of inclusive double-differential neutron spectra for incident protons above 100 MeV. A powerful feature of the presented approach is the ability to predict the model bias for energies angles and isotopes where data are missing. The number of experimental data points that can be taken into account is at least in the order of magnitude of 104 thanks to the sparse approximation. The approach is applied to the Liège intranuclear cascade model coupled to the evaporation code ABLA. The results suggest that sparse Gaussian process regression is a viable candidate to perform global and quantitative assessments of models. Limitations of a philosophical nature of this and any other approach are also discussed. 1 Introduction The definition of these two quantities induces a prior probability distribution