Nucleus-Nucleus Collisions...  Nuclear Structure under Extreme  Special instrumentation

Concluding Recommendations

In recent times we have made significant progress in our understanding of nuclear structure. We have passed important milestones and we are now faced with challenging new questions. These questions address the properties of the nucleus at the limits of excitation energy, spin, isospin, and mass. The rapid development of highly efficient experimental techniques for the detection of photons, charged particles, and neutrons makes the investigation of the central issues of nuclear structure possible. These include questions related to extreme nuclear shapes and their evolution, and the influence of the thermal environment on both low-lying modes and giant modes of excitation. Radioactive beam facilities will open the way to the study of new phenomena near the drip-lines, such as halo nuclei, neutron skins, neutron-proton pairing, the evolution of shell structure and exotic collective modes. At the same time, they will make it possible to test directly our ideas of how the chemical elements are created in stars. Great advance in our knowledge of the limits to the existence of nuclei is expected. Extrapolating from the recent observation of element 112, which lies near the predicted region of shell-stabilised nuclei, the synthesis of superheavy elements may come within reach of the next generation of radioactive beam facilities. To this end we recommend the following actions:

• If we are to exploit fully the detectors and other instruments created by recent major investments, and reach our scientific goals, nuclear structure studies rely on the continuing availability of accelerators providing high quality beams of stable and radioactive ions. Those accelerator laboratories which already form a European network of complementary facilities for nuclear research must be supported and further improved.
• Nuclear structure studies on nuclei at the limits of stability require accelerators with the highest possible luminosities and detectors of maximum efficiency. European collaborations involved in developing powerful new detector systems, the operation and construction of the first generation of radioactive beam facilities and R&D on high-power ion-sources and targets should be strongly supported.
• NuPECC should set up a study group to investigate and assess the main options for second generation radioactive beam facilities in Europe based on both the fragmentation and on the ISOL methods.
• Measures should be taken to strengthen and reinforce the theoretical physics community in order to mirror and support the thriving experimental programme. In particular, European universities must be committed to this goal by creating positions in theoretical nuclear physics. NuPECC should support the activities of the ECT$^\ast$ centre of Trento and help create adequate and more stable funding for it.