| Abstract: | The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light
neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams
produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent
experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI
and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects
of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the
dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the
changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems.
The vanishing of the N = 8 shell gap for neutron-rich systems like 11Li and 12Be, or the new closed N = 14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied
by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley
of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei,
which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei, in particular,
show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of
the projectile. Finally, an outlook on future experimental prospects is given. |
