Abstract :
The acceleration of secondary, radioactive beams from primary beam driven ion sources provides many challenges when compared to the case of conventional ion beams. The clean separation of the specific ion species, the low beam current, the short life time of the ions as well as the needed energy variability have consequences on the layout of the accelerator. As also experiments with astrophysical relevance are performed, the energy range should go down below 1 MeV/u in some cases. Additionally, to investigate nuclear reactions around the Coulomb barrier, the beam energy should be flexible up to around 8 MeV/u. Short isotope life times below a few milliseconds do not allow for charge breeding. In these cases, low charged ions from ‘simple’ ion sources have to be accepted by the accelerator. Furthermore, stripping processes along the linac are excluded in case of low beam currents. Multicoincidence experiments profit a lot from cw operation of ion source and accelerators. During the last three decades, room temperature H-type linac structures were developed, which can provide solutions for all cases mentioned above. A 1.4 MeV/u high-current H-type linac was successfully commissioned in 1999 at GSI, which can accelerate mass over charge ratios A/q up to 65 and currents in emA up to 0.25A/q. These capabilities are also attractive for the front end of a RIB heavy-ion driver linac. Superconducting linac solutions with short cavities were realized successfully in quite a number of laboratories. Prototype development on cold multicell structures has started just recently.
