Nuclear physics with a crystal ball

The paper describes selected experiments carried out with the Darmstadt- Heidelberg crystal ball, to demonstrate the versatility of the 4π multi-detector arrays. Two examples from studies of nuclear structure are reviewed; one on the double γ-decay in nuclei, the other on giant resonances of highly excited states. Two examples from nuclear reaction mechanisms are also reviewed; one concerns heavy ion fusion, and the other heavy ion scattering. (UK)