The origin of all the elements we observe in the Universe is an open question that motivates a sizable amount of research today. Nucleosynthesis models aim to explain the relative abundance of nuclei we observe and identify the astrophysical phenomena that can host different nuclear transmutation processes, each with a different fingerprint in terms of the matter being produced. We now understand quite well the production of many lighter nuclei in the interior of stars during comparatively quiescent periods in their evolution, but the same cannot be said for nuclei heavier than iron. The rapid neutron-capture process (r-process) is responsible for the creation of about half of such elements; the recent observation of the gravitational wave signal GW170817 and its optical counterpart in August 2017 has confirmed that this process at least occurs during one astrophysical event: the cataclysmic merger of two neutron stars. Despite this recent progress, many open questions remain, perhaps the most important being whether neutron star mergers are the prime locus of r-process nucleosynthesis, i.e. whether they contribute significantly to the overall production of heavy nuclei in the Universe.

Astrophysical questions such as r-process nucleosynthesis and the structure of neutron stars provide motivation to improve on the modeling of the structure and reactions of atomic nuclei, research that is also driven by other applications and fundamental curiosity. Arguably the most stringent test of our understanding of the latter is our capability to construct models that accurately describe the properties known nuclei yet can reliably extrapolate into unknown regimes, whether these are large neutron/proton imbalances or extreme densities, excitation energies and temperatures.

This post-doctorate fellowship fits into the larger aims of the Brussels group to provide nuclear structure data for astrophysical applications. The IAA has a long-standing history of building large-scale models of nuclear structure; the most recent models – the BSkG series - accurately describe static properties of nuclei (masses, radii, level densities, …) across the whole nuclear chart based on a rich symmetry-broken microscopic description of all nuclei that underpins our confidence in the reliability of extrapolations. The goal of this project is to extend the reach of these models to dynamic properties of nuclei: we will develop a linear response or QRPA tool to complement the existing numerical suite. By means of the finite-amplitude method, this new tool will be sufficiently numerically efficient to allow for its use on the scale of the entire nuclear; the first application of this tool will be the global calculation - based on the latest BSkG model - of photostrength functions, a crucial ingredient to estimate reactions involving electromagnetic radiation. The successful candidate will assist the groups efforts to update BRUSLIB (http://www.astro.ulb.ac.be/bruslib/) for optimal dissemination of results, in particular by
incorporating photostrength functions in the database. There are many possibilities to further extend this work, from detailed comparison to recent experimental data to applying the tool to beta decay and fission rates but also to improve future models with linear response information.

The Post-doctorate position is funded for two years at the Institut d’Astronomie et d’Astrophysique (IAA) of the Université Libre de Bruxelles. We form a dynamic group with expertise on many aspects of the role of nuclei in the cosmos with regular group meetings, a cordial culture of open discussion and significant possibilities for to form fruitful collaborations. The screening of applications for this position begins immediately and continues until an outstanding candidate is selected. Ideally, the successful candidate is to start as soon as possible.

Interested candidates should send their CV and request two referees to send their recommendation letter directly to W. Ryssens at wouter.ryssens@ulb.be.

Contact:
Dr. W. Ryssens
Institut d’Astronomie et d’Astrophysique
Université Libre de Bruxelles
Campus de la Plaine CP 226
B-1050 Brussels, Belgium
Email: wouter.ryssens@ulb.be