Laser cooling of relativistic C3+ beams at the ESR

We report on new results for laser cooling of bunched C3+ beams at the ESR stored at an energy of 1.46 GeV. We observe a longitudinal momentum spread one order of magnitude smaller compared to conventional electron cooling. Using a setup of two cw Ar+ lasers, one at a fixed frequency, the other constantly detuned with respect to the first, we were able to increase the momentum acceptance of the laser force compared to recent experiments. If laser cooling is assisted by moderate electron cooling 3D cold beams can be achieved. The focus of the talk lies on the dynamical aspects of the transition from temperature dominated beams to space charge dominated beams