Laser Cooling of Relativistic Heavy Ion Beams

We report on the experimental demonstration of laser cooling of a C³⁺ion beam performed at the ESR (GSI) at an energy of E = 1.47 GeV. The decelerating laser force of one Doppler-tuned UV laser beam was counteracted by moderately bunching the beam. This versatile scheme lead to longitudinally ‘space-charge dominated’ beams with an unprecedented momentum spread of Δp/p ≈ 10^–7. Concerning beam energy and charge state of the ion, the experiment depicts an important step from the field of laser cooling of ion beams at low energies toward the laser cooling scheme proposed for relativistic beams of highly charged heavy ions at the future GSI facility FAIR.