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
centre of Trento and help create adequate and more stable funding for it.