Status of REX-ISOLDE

Abstract

REX-ISOLDE [1] is a post-accelerator situated at the ISOLDE radioactive ion beam facility placed at CERN, Geneva. It’s main aim is to increase the energy of light (A < 50) radioactive ions from 60 keV to 0.8–2.2MeV/u. REX—ISOLDE uses a new concept of post-acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In a first step the radioactive ions are captured in a large gas-filled Penning trap. The task is to accumulate, cool and bunch the beam and prepare it for the injection into an electron beam ion source (EBIS). Cooling of the ions is achieved by collisions with a buffer gas and an efficient side band cooling mechanism by applying an rf field with a frequency equal to the cyclotron frequency of the desired ion species. The ions are then transported to an EBIS, where there charge state will be increased from 1+ to n+. For an efficient acceleration in the LINAC a charge to mass ratio of 1/4.5 is desired. After charge breeding the ions are extracted from the EBIS and re-accelerated to an energy of 5keV/u.