First radioactive ions charge bred in REXEBIS at the REX-ISOLDE accelerator

REXEBIS is the charge breeder of the REX-ISOLDE postaccelerator. Radioactive 1⁺ ions produced at ISOLDE are accumulated, phase-space cooled and bunched in REXTRAP, and thereafter injected into the EBIS with an energy of up to 60 keV. The REXEBIS produced the first charge bred ions in August 2001 and has been running nearly non-stop from September to December 2001. It has delivered stable ³⁹K¹⁰⁺ and ²³Na⁷⁺ beams generated in the test ion-source in front of REXTRAP with a current of 12 pA for K¹⁰⁺ and a Na⁷⁺ current exceeding 70 pA (6 × 10⁷ p/s). Stable ²⁷Al⁷⁺ and ²³Na⁶⁺ (about 10 pA) and also the first radioactive ²⁶Na⁷⁺ and ²⁴Na⁷⁺ beams (just 0.4 pA or 5 × 10⁵ p/s), from the ISOLDE separator have been charge bred and accelerated for tests of the experimental setup. Despite some problems with the LaB₆ cathode (one total breakdown after about 1500 h of operation), displaying slow changes of the emission conditions, the EBIS is working remarkably stable. We report about the first ion injections, ion source details, cathode conditions as well as other commissioning results.