The majority of elements beyond the Fe peak are produced by neutron capture processes which can be rapid (r-process) or slow (s-process) with respect to the beta-decay in nuclei. Understanding which are the astrophysical formation sites of these two processes has become one of the major challenges in chemical evolution. In this talk, I will first present the main steps done in chemical evolution simulations in order to understand the origin of neutron capture elements and then I will show results from our latest work in which the predictions of our updated chemical evolution model (with state-of-the-art nucleosynthesis prescriptions) are compared with data from the sixth data release of the Gaia-ESO survey. We studied both the abundance patterns and the radial gradients of five s-process elements (Y, Zr, Ba, La, Ce) and four mixed/r-process elements (Eu, Mo, Nd, Pr). Our results show that the production of r-process material from a prompt source is needed in order to reproduce observations of both the [Eu/Fe] and the [s-/Fe] vs. [Fe/H] abundance pattern. This quick source can be represented by MR-SNe which, however, appear to dominate the production of neutron capture elements. Nevertheless, the predicted [Eu/H] radial gradient slope is steeper than the observed one, regardless of how quick the production of Eu is, prompting discussion on different Galaxy formation scenarios and possible stellar radial migration effects.
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