THE REX-ISOLDE PROJECT

The Radioactive beam Experiment (REX-ISOLDE) (D. Habs et al., Proposal to the ISOLDE committee, CERN-ISC94-25) a pilot experiment testing a new concept of post acceleration of radioactive ions at ISOLDE/CERN is now under progress. A further goal of the experiment is the spectrosc opy of very neutron rich nuclei by Coulex and transfer reactions (D. H abs et al., Nucl. Phys. A 616 (1997) 29c), Radioactive singly charged ions delivered by the on-line mass separator ISOLDE are first accumula ted in a Penning trap, then charge breeded to A/q = 4.5 in an electron beam ion source (EBIS) and finally accelerated in a LINAC to the fina l energy between 0.8 and 2.2 MeV/u. First tests will be done with the Penning trap to measure efficiencies and the ion capacity of the trap. In the next shut down period of ISOLDE the charge breeding and the ma ss separation system will be installed. Meanwhile the resonant structu res of the LINAC consisting of a Radio Frequency Quadrupole (RFQ) acce lerator, an interdigital H-type structure (IH) and three seven gap res onators, which allow a variation of the final beam energy are under co nstruction and models are built. The design of the RFQ has slightly ch anged to get a less diverging beam at the RFQ exit to decrease the con straints of the matching section. The change of the final energy of th e IH-structure by adjusting the gap-voltage distribution due to capaci tive plungers has been calculated with MAFIA and tested by model measu rements. This paper gives an overview of the status of the project and of the final design of the LINAC. (C) 1998 Published by Elsevier Scie nce B.V.