First $\gamma$-rays from radioactive beams at REX-ISOLDE

In order to demonstrate a novel scheme to accelerate radioactive ions and to provide radioactive ion beams for physics experiments, the radioactive beam experiment (REX) was installed at ISOLDE, CERN. One of the main experimental devices that will use these beams is the newly commissioned HPGe array MINIBALL featuring an excellent granularity, energy resolution, and rate capability. First experiments have been performed using beams of neutron-rich Na and Mg isotopes. (8 refs)