On the Few-Body Character of Light Exotic Nuclei - Analytical Studies of Electromagnetic Processes Involving Loosely Bound Systems

Doktorsavhandling, 2003

The few-body character of loosely bound nuclei along the drip lines is studied within an analytical approach. It is argued that the clusterization of these systems leads to a modification of the normal phase space distribution of fragment momenta in breakup reactions. In this context, it is shown how correlations in the initial state can be taken into account when analyzing invariant mass spectra. Furthermore, it is demonstrated that the bound state structure of Borromean systems is reflected in the electric dipole strength function, and that the accumulation of strength at low energies is mainly an effect of the small binding energy and large intercluster distances. Consequently, important information concerning the ground state structure of two-neutron halo nuclei can be extracted from electromagnetic dissociation experiments, and results are shown for 6He, 11Li and 14Be. It is pointed out that the existing data sets for 11Li and 14Be are, to a large extent, contradictory. In addition, the 14Be mass should be remeasured. Finally, the interesting proton halo candidate 8B is studied, and the importance of both two- and three-body dynamics is discussed. In connection to this problem, two novel methods to extract astrophysically interesting information from electromagnetic dissociation experiments are proposed.