Study On Laser Cooling At The Heavy Ion Storage Ring

Compared with the stochastic cooling and electron cooling,the laser cooling is expected to obtain much higher cooling rate,which results in higher phase space densities to achieve phase transition for ordered beam or crystallized beam.Laser cooling of relativistic heavy ion beams of Li-like C3+ and O4+ is being in preparation at the experimental Cooler Storage Ring(CSRe).Recently,some preparatory experiments to test important prerequisites for laser cooling of relativistic 12C3+ ion beams using a pulsed laser system have been performed at the CSRe.Unfortunately,the interaction between the ions and the pulsed laser can not be detected.In order to study the laser cooling process and find the optimized parameters for future laser cooling experiment,a multi-particle tracking method was developed to simulate the detailed longitudinal dynamics of laser-cooled ion beams at the CSRe.The simulations of laser cooling of the 12C3+ ion beams by scanning the frequency of RFbuncher or CW laser wavelength were performed.The simulation results indicated that a large momentum spread ion beams could be laser-cooled by the combination of only one laser and the RF-buncher and shown the requirements of a successful laser cooling experiment.The optimized parameters for scanning the RF-buncher frequency or laser frequency were obtained.Furthermore,the heating effects were estimated to find the final and balance state between laser cooling and the growth of the intra beam scatting.Finally,the Schottky noise spectra of longitudinally modulated and laser-cooled ion beams was simulated to fully explain and anticipate the experimental results.The combination of Schottky spectra from the highly sensitive resonant Schottky pick-up and the simulation methods developed in this paper will be helpful to investigate the longitudinal dynamics of RF-bunched and ultra-cold ion beams in the upcoming laser cooling experiments at the CSR.