The Heavy Ion Storage Ring ESR (Experimental Storage Ring) provides the worldwide unique possibility to store and accumulate ions to the highest possible currents for all ions, from helium up to bare uranium (see fig. 1). This allows the investigation of physics with the heaviest available ions.

Fig. 1: The experimental range of the ESR

The kinetic energy of the stored ions ranges from below 10% to almost 90% of the speed of light. The setup of six 60° dipole magnets together with the focusing quadrupole magnet systems guides the ions along their ideal orbit. A high brilliance of the circulating ion beams, which means very small diameters and angular divergences and an extremely small velocity distribution is obtained and preserved by applying special techniques like electron- or laser-cooling. Figure 2 shows a schematic of the ESR together with the position of the electron-cooler, the gas-jet and other experimental setups.

Fig. 2: Schematic of the Experimental Storage Ring ESR

The ESR ring has a circumference of 108.36 m and a magnetic rigidity of 10 Tm. The high vacuum inside the ring of the order of 10E-11 mbar is essential for a low collision-rate between the stored ions and the atoms of the rest gas which causes charge state changes of the ions and lead to drastic intensity losses of the stored beams.

For more information see:

• ESR at GSI-Webpage


• R. Reuschl, PHD thesis:
  Untersuchungen zur Lamb-Verschiebung in schweren Ein- und Zwei-Elektronen-Systemen (German)
  - pdf


• A. Gumberidze, PHD thesis:
  Experimental studies of the ground state QED corrections in H- and He-like uranium (English)
  - pdf