Spectroscopy of exotic nuclei with multi-nucleon transfer reactions

Structure investigations of neutronrich helium isotopes and of Li-10 and Be-11 have been performed using multi-nucleon transfer reactions. New results have been obtained for He-7, where we have evidence for the observation of the first excited state, i.e. the 1/2(-)-resonance, which is of interest for the spin-orbit splitting in these light neutronrich nuclei. Our results on He-8, He-9 and He-10 are briefly summarized. Reactions of distinct selectivity have been chosen to study the states of Li-10. The structure of the eight states found in these reactions is discussed, as well as their relevance for the decay of Li-11 resonances. The isotopes Be-10 and Be-11 have been investigated to study the alpha-cluster structure and high-lying states. Nine states of the observed Be-11-resonances can be characterized as a molecular rotational band extending up to 25 MeV excitation energy, with a probable maximum spin of 19/2. The reaction mechanism is studied in terms of two-step calculations, where protons are picked-up from the target and neutrons are transferred to the target. Using measured strength amplitudes for the single steps results in a quantitative description of the observed two-step cross sections.