The aim of nuclear structure studies is to understand the evolution of the basicproperties of the atomic nucleus (among which its mass, decay properties andshape) as the balance between the number of protons and neutrons changes.
The variety of the production modes combined with efficient separation and detection devices allows studying in detail the structure of the most exotic nuclei, either located far from the valley of stability with respect to beta decay or lying in the region of the super-heavy elements.
The observed evolutions are used to constrain the modelization of the nuclear forces, which are as well probed through the study of some specific fundamental interactions.
Our knowledge of the quantal nature of the nucleus is coming essentially from nuclear structure studies. However, this knowledge relies on the detailed study of some stable nuclei and the only way to test the validity of the various theories is to study the atomic nucleus at the limits. Exploring the nuclear structure and the decay properties of these exotic nuclei allows magnifying specific terms in the Hamiltonian (e.g spin-orbit coupling, pairing interaction, or effective mass) which are small in the case of beta-stable nuclei.
What are these limits? For the field of nuclear structure, the frontiers are:
* the N/Z ratio
* the nuclear mass and charge
* the angular momentum and excitation energy
In recent years, the nuclear structure of exotic nuclei has been investigated at GANIL through the study of:
– halo nuclei and cluster structures
– spectroscopic studies by means of direct reactions
– on-line spectroscopy by means of deep inelastic transfer reactions
– magnetic and quadrupole moment measurements
– isospin symmetry
– exotic decay modes
– giant nuclear resonances
Nuclear astrophysics studies are focused on the measurement of nuclear reaction cross sections and on the characteristics of the involved nuclear resonant states.
GANIL is involved in the quest and the study of the heaviest elements. The observation and location in the (N,Z) landscape of the next spherical doubly magic gap is essential experimentally if one wants to establish and validate theoretical models. Another approach for this quest is the spectroscopic study of the very heavy elements located beyond Z=100 which lead to information relevant for the microscopic understanding of the superheavy elements.