In this article, we will first discuss the issues of the prompt g-ray spectroscopy regarding the control of all the uncertainties involved in the (n,n0g) cross section estimation. Secondly, we will focus on the role of theoretical modeling which, in certain cases, is crucial to reach the objectives of a few percent uncertainty on the (n,n0) cross sections. | How to produce accurate inelastic cross sections from an indirect measurement method EPJ Nuclear Sci. Technol. 4 23 2018 Nuclear Sciences M. Kerveno et al. published by EDP Sciences 2018 amp Technologies https epjn 2018020 Available online at https REGULAR ARTICLE How to produce accurate inelastic cross sections from an indirect measurement method Maëlle Kerveno1 Greg Henning1 Catalin Borcea2 Philippe Dessagne1 Marc Dupuis3 Stéphane Hilaire3 Alexandru Negret2 Markus Nyman4 Adina Olacel2 Eliot Party1 and Arjan Plompen4 1 Université de Strasbourg CNRS IPHC UMR 7178 Strasbourg France 2 Horia Hulubei National Institute of Physics and Nuclear Engineering Bucharest-Magurele Romania 3 CEA DAM DIF Arpajon France 4 European Commission Joint Research Centre Geel Belgium Received 31 October 2017 Received in final form 8 March 2018 Accepted 14 May 2018 Abstract. Inelastic reactions n xn for x 1 play a key role in reactor cores as they influence the slowing down of the neutrons. A reactor neutron energy spectrum depends thus on this process which is in strong competition with elastic scattering and fission a nice example is the case of 238U. Inelastic scattering x 1 impacts keff and radial power distribution in the nuclear reactor. For several years it has been shown that the knowledge of the inelastic cross sections in nuclear databases is not good enough to accurately simulate reactor cores and a strong demand for new measurements has emerged with very tight objectives only a few percent for the uncertainties on the cross section. To bypass the well-known experimental difficulty to detect neutrons the prompt g-ray spectroscopy method is a powerful but indirect way to obtain inelastic cross sections. Our collaboration has used this method for more than ten years and have produced a lot of n n0 g cross sections for nuclei from 7Li to 238U. In this article we will first discuss the issues of the prompt g-ray spectroscopy regarding the control of all .