Ring accelerator SIS18—the record holder The ring accelerator SIS18 © Photo: A. Zschau, GSI Helmholtzzentrum für Schwerionenforschung GmbH Cavity of SIS18 Ions coming from the linear accelerator UNILAC [...] l storage ring ESR for storage and further analysis. 216 meters: The SIS18 has a circumference of 216 meters. 92 elements: The SIS18 can accelerate ions of all natural chemical elements of the periodic [...] UNILAC can be accelerated to up to 90 percent speed of light (270,000 km/s) with the SIS18. 80,000 volts: Ions in the SIS18 are accelerated by a voltage of 80,000 volts in the accelerator structures during