Potential of prompt γ-ray emission studies in fast-neutron induced fission : a first step

Prompt gamma-ray spectra emitted in fast-neutron induced fission of 239 Pu have been recently measured by using the LICORNE directional neutron source at En = 1.8 MeV. The results are used in parallel with the measurements of fast-neutron induced fission of 238 U and spontaneous fission of 252Cf to assess the potential of such reactions and observables, in contributing to the understanding of fission. The gamma-ray spectra were measured and analyzed under similar conditions, allowing a consistent and robust comparison between the three systems. They are further compared to Monte-Carlo simulations based on two widely-used semi-empirical codes, FREYA and GEF. Differences in the low and high energy portions of the spectrum are interpreted based on simple arguments involving nuclear structure and evaporation effects. The significance and potential of experimental campaigns of this kind, as well as current limitations, are highlighted, together with straightforward but mandatory extensions.