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The Belgian Research Initiative on eXotic nuclei for atomic, nuclear and astrophysics studies (BriX)

Research project P7/12 (Research action P7)

Persons :

Description :

The prime aim of the Belgian Research Initiative on eXotic nuclei (BriX) network is the study of atoms and atomic nuclei with an unusual proton-to-neutron ratio, so-called exotic nuclei. The proposed research rests on four main pillars: nuclear structure and reactions, nuclear astrophysics, fundamental interactions and atomic physics. Intertwined experimental and theoretical studies are at the junction of these different domains. Key experiments, for which dedicated instrumentation and new technologies will be used and developed, are decay and laser-spectroscopy studies, moment measurements, Coulomb excitation and other reactivity measurements using exotic nuclei. Theoretical studies cover few-body structure and reaction models, beyond-mean-field descriptions, and shell models and their symmetries for nuclear physics, global nuclear models for nuclear astrophysics as well as relativistic and electronic correlations in multi-electron systems for atomic physics studies. Added to this and to secure the long-term future of this line of research, a technical design study and fine tuning of the physics potential of the ISOL@MYRRHA project, an on-line separator coupled to the Belgian MYRRHA proton accelerator, will be undertaken.

Belgian partners of the universities of K.U.Leuven, ULB (Brussels), UGent, ULg (Liège) and of the research institute SCK•CEN (Mol) together with the international partners from GANIL-Caen and CEA/IRFU-Saclay (France), and GSI-Darmstadt and UKöln (Germany) will operate under the BriX network. By combining the expertise present in this new network, the opportunities offered by the European accelerator facilities (mainly ISOLDE-CERN, GANIL and GSI), the new instrumentation and theoretical approaches developed during the previous phase and the new opportunities that will become available with the MYRRHA accelerator, three main objectives that are in-line with the recommendations of the NuPECC Long Range Plan 2010 are identified. We plan:

- to study exotic nuclei in order to improve our understanding of the strong and weak interactions active in the nuclear medium and to improve the predictability of nuclear and nuclear-astrophysics models
- to study the atomic structure of exotic nuclei, including the heavy elements, to validate and improve atomic theory and to supply essential information for the interpretation of laser-spectroscopy data
- to make use of the unique opportunities offered by the MYRRHA proton accelerator in Belgium by setting crucial steps towards the realization of the ISOL@MYRRHA project.

Compared to the previous phase, the network has been extended with several new Belgian research groups: atomic-physics (ULB and ULg), nuclear astrophysics (ULB), nuclear spectroscopy (ULB) and nuclear-reaction theory (UGent). CEA/IRFU-Saclay (France) joins as a new international partner with expertise in nuclear theory, nuclear reactions, fission studies and Super Heavy Element research. BriX brings together expertise on theoretical and experimental nuclear physics, nuclear astrophysics and atomic physics, and will execute, in a coherent and collaborative effort, a research program focussed around radioactive ion beam research. Together with the international partners, a carefully selected sample of atomic nuclei most of them with extreme proton to neutron ratios will be investigated to reach the following research goals:

- study their nuclear structure and reactivity in the light mass region, along closed proton and/or neutron shells and towards the heaviest elements
- examine their response to strong and electroweak probes to gather information about their equation of state
- probe fundamental interactions through their decay characteristics
- explore their atomic properties including the structure of the heavy elements
- investigate the properties of nuclei of interest for nuclear astrophysics

Extended experimental campaigns at the radioactive beam facilities of ISOLDE-CERN (Switzerland), GANIL (France) and GSI (Germany) as well as smaller campaigns at other facilities are foreseen. The major theoretical efforts will be closely related to the experimental work in order to stimulate mutual feedback between theory and experiment.

The proposed network is fully embedded in the road towards the next-generation radioactive beam facility EURISOL and FAIR and will guarantee a continued visible role of Belgian research groups on the international scene of radioactive-beam research of interest for atomic, nuclear and astrophysics. The theoretical and experimental advances generated by the network will flow into the detailed study of the physics-research potential and the design of the ISOL@MYRRHA facility.