The 252Cf(sf) prompt fission neutron spectrum (PFNS) is a reference neutron data that is widely used as a well known neutron flux for cross section measurements and neutron detector characterization. The current evaluation of the spectrum dates from the work of Mannhart in 1988. With the improvement of detection systems, the uncertainty on the spectrum has an increasingly significant impact on the uncertainty of new nuclear data measurements using it as a reference. Improving the precision on the 252Cf(sf) PFNS would therefore have a wide impact on the nuclear data community and improve the uncertainties on all data that were measured with respect to this reference spectrum. The thesis aims to measure again the 252Cf(sf) PFNS with a focus on the region below 1 MeV and the region above 8 MeV, where the uncertainties are greatest, using recoil proton detectors. The chosen candidate will have to actively participate to the design and construction of the setup, leading the technological choices through simulations, will participate to the experiment and do the data analysis. The work will then be presented in international conferences and peer-reviewed articles.

9Be plays a central role in fusion technology and in material testing reactor (MTR) as a neutron source moderator. However, existing nuclear data for neutron scattering on 9Be exhibit significant uncertainties, particularly in the 1.5-15 MeV energy range. In order to provide high quality data for improving nuclear reaction models and evaluated nuclear data libraries, an experiment to measure the elastic and inelastic scattering of neutrons on a 9Be target was proposed and accepted at the Neutrons For Science (NFS) facility. Neutrons will be measured using the recently developed VErsatile Neutron DETector Array (VENDETA), formed of high-resolution time-of-flight detectors which combine excellent neutron/gamma discrimination and efficiency down to 100 keV. The experiment will employ the quasi-monoenergetic neutron beams available at NFS from the p+7Li reaction, enabling a systematic investigation of scattering observables as a function of incident neutron energy.
The chosen candidate will lead the analysis to extract angular differential cross sections for both elastic and inelastic channels as a function of the incoming neutron energy. The data will have a direct impact on applications in nuclear energy and shielding design, while their interpretation in terms of partial decay width to the elastic and inelastic channels will improve our understanding of 9Be and 10Be nuclear structure.

Radiative neutron capture is a nuclear reaction forming a compound nucleus which decays by emitting gamma-rays at excitation energy around the neutron binding energy. This well-known reaction which we known how to accurately measure its cross section at low incident neutron energies for most stable and few unstable nuclei close the stability valley, remains difficult to measure for exotic nuclei like fission fragments. Nuclear reaction models based essentially on stable nuclei, also struggle to provide reliable predictions of cross sections for these exotic nuclei. However, in the recent years, progress made related to the models and the measurements for the radiative capture show that significant improvements in including microscopic ingredients studies. These micoscopic ingredients: gamma strength function and nuclear level density, remain accesible to the experiment. These ingredients which respectively manage the way of how the gamma cascade occurs and the nuclear structure at high excitation energy can also be measured and calculated to be compared and suggest ways to improve the predictability of models. This kind of improvements have a direct impact for instance on the cross sections for these exotic nuclei which are produced in the stellar nucleosynthesis. The subject of thie thesis is to measure these quantities for a nucleus involved in the nucleosythesis using a new setup called SFyNCS.