The $^{154}$Gd neutron capture cross section measured at the n_TOF facility and its astrophysical implications

International audienceThe (n,$\gamma$ cross sections of the gadolinium isotopes play an important role in the study of the stellar nucleosynthesis. In particular, among the isotopes heavier than Fe, $^{154}$Gd together with $^{152}$Gd have the peculiarity to be mainly produced by the slow capture process, the so-called s-process, since they are shielded against the $\beta$-decay chains from the r-process region by their stable samarium isobars. Such a quasi pure s-process origin makes them crucial for testing the robustness of stellar models in galactic chemical evolution (GCE). According to recent models, the $^{154}$Gd and $^{152}$Gd abundances are expected to be 15-20% lower than the reference un-branched s-process $^{150}$Sm isotope. The close correlation between stellar abundances and neutron capture cross sections prompted for an accurate measurement of $^{154}$Gd cross section in order to reduce the uncertainty attributable to nuclear physics input and eventually rule out one of the possible causes of present discrepancies between observation and model predictions. To this end, the neutron capture cross section of $^{154}$Gd was measured in a wide neutron energy range (from thermal up to some keV) with high resolution in the first experimental area of the neutron time-of-flight facility n_TOF (EAR1) at CERN. In this contribution, after a brief description of the motivation and of the experimental setup used in the measurement, the preliminary results of the $^{154}$Gd neutron capture reaction as well as their astrophysical implications are presented.