Author: Yuan, Y.J.
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P1004
 Simulation of Bunched Schottky Spectrum for Laser-Cooled O5+ Ions at CSRe  
 
  • H.B. Wang, D.Y. Chen, X. Ma, W.Q. Wen, Y.J. Yuan
    IMP/CAS, Lanzhou, People’s Republic of China
  
  Laser cooling of O5+ ion beams with an energy of 275.7 MeV/u was successfully achieved at the storage ring CSRe in Lanzhou, China. In order to explain the experimental results, by employing the multi-particle tracking method we made simulations of the bunched Schottky spectrum of O5+ ions with and without laser cooling. In the simulation, both of the transverse oscillation and the photon-ion resonant interaction process are considered while intra beam scattering is ignored. For bunched ion beams without laser cooling, the power of the central peak is about several orders of magnitude larger than that of the sideband peaks, which was called the "coherent effect". The simulation systematically studied the relationship of the Schottky power and the ions number at different observation harmonics and make clear about this ’coherent effect’ for the first time. For laser-cooled bunched ion beams, with more ions laser-cooled to center of the bucket, the distribution of the Schottky spectrum becomes narrower than that of the uncooled ion beams. However, the simulated bunched Schottky spectrum for laser-cooled ion beams shows strong sidebands at the position where laser resonant interacts with ions. The reason is that the beta-oscillation in the laser cooling straight section is simplified by using a mean betatron-function value. The further simulation is in progress. With this simulation, the dynamics for the laser cooling of bunched ion beams are fully understood for the first time.  
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P2007
 Anomalous Longitudinal Schottky Signals of Coasting Ion Beams with Interaction of a CW laser at Storage Ring CSRe  
 
  • D.Y. Chen, Z. Huang, X. Ma, H.B. Wang, W.Q. Wen, Y.J. Yuan
    IMP/CAS, Lanzhou, People’s Republic of China
  • D. Zhang
    Xidian University, Xi’an, People’s Republic of China
  
  Laser cooling of relativistic heavy ion beam is considered as frontiers at the current heavy storage ring CSRe as well as the future High Intensity heavy-ion Accelerator Facility (HIAF) at the Institute of Modern Physics in China. Laser cooling of lithium-like 16O5+ ion beams with a relativistic energy of 275.7 MeV/u has been realized for the first time at the CSRe. In this experiment, a very broad interaction range of the counter-propagating fixed cw laser with a coasting ion beam has been observed on the longitudinal Schottky spectrum, which is much broader than the estimated width caused by the natural linewidth of the laser and ion’s optical transition*. In order to understand this anomalous observation, a single-particle tracking method has been developed to investigate the interaction of coasting ion beams and a cw laser. It is found that the interaction range is highly enlarged by the betatron oscillations of the ion beams in the transverse plans caused by the focusing and defocusing of quadrupoles in the straight section of the CSRe. The good agreement between simulations and experimental results lay a foundation for our simulations of the laser cooling of bunched ion beams and paves the way for the forthcoming experiments of laser cooling and precision laser spectroscopy at the storage ring CSRe.
* W. Wen, H. Wang, Z. Huang, et al., Hyperfine Interactions, 240:45 (2019). 		 
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