Author: Wang, H.B.
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S604
 Laser Cooling of Stored Relativistic Ions Using a New Pulsed UV Laser System (Very High Repetition Rate, Variable Pulse Duration, More Power)  
 
  • D.F.A. Winters, L.H.J. Bozyk, S. Klammes, T. Kühl, R.M. Sanchez Alarcon, P.J. Spiller, M. Steck, T. Stöhlker
    GSI, Darmstadt, Germany
  • G. Birkl, N. Eizenhöfer, M. Horst, D. Kiefer, B. Langfeld, W. Nörtershäuser, T. Walther
    TU Darmstadt, Darmstadt, Germany
  • A. Buss, V. Hannen, K. Ueberholz, D. Winzen
    Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany
  • M.H. Bussmann, M. Löser, U. Schramm, M. Siebold
    HZDR, Dresden, Germany
  • M.H. Bussmann
    CASUS, Görlitz, Germany
  • D.Y. Chen, Z. Huang, X. Ma, H.B. Wang, W.Q. Wen
    IMP/CAS, Lanzhou, People’s Republic of China
  • N. Kiefer
    Universität Kassel, Kassel, Germany
  • W. Nörtershäuser, T. Walther
    HFHF, Frankfurt am Main, Germany
  • T. Stöhlker
    HIJ, Jena, Germany
  • T. Stöhlker
    IOQ, Jena, Germany
  • C. Weinheimer
    Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany
  
  Funding: Collaborative research program of the Federal Ministry for Education and Science, Germany. BMBF: ErUM-FSP APPA
We present our new (but still preliminary) results from a recent test beamtime for laser cooling of carbon ions (12C3+ @ 122 MeV/u) at the ESR. In May 2021, GSI kindly offered us the possibility to test the new pulsed UV laser system from the TU Darmstadt, which has a very high repetition rate (10 MHz), a variable pulse duration (70 - 740 ps) and more power (up to 250 mW). We have demonstrated laser cooling using this laser and present results for different laser pulse durations (166 - 740 ps). In addition, we could test the improved moveable in-vacuo fluorescence detection system from Münster University. Finally, we could also demonstrate our new ion bunch - laser pulse timing scheme and observe clear delay effects. 		 
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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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P1006 Design of the SRing Electron Target 78
 
  • J. Li, Z. Huang, H.J. Lu, F. Ma, X.M. Ma, X. Ma, L.J. Mao, X.P. Sha, G.D. Shen, M.T. Tang, H.B. Wang, S.X. Wang, W.Q. Wen, T.L. Yan, J.C. Yang, X.D. Yang, L.X. Zhao, Y.B. Zhou
    IMP/CAS, Lanzhou, People’s Republic of China
  
  An electron target is proposed for high precision experimental measurement at the SRing (Spectrometry Ring) of HIAF (High Intensity heavy ion Accelerator Facility). It provides low temperature electron beam with a few meV for DR (Dielectronic Recombination) experiments at the energy of 1-§I{80}{keV}. For such a low temperature, the conventional method is adopted by magnetic adiabatic expansion with a factor of 30 after acceleration within 1.2T longitudinal magnetic field at gun section. In this paper, the design optimization of the electron target is introduced.  
poster icon Poster P1006 [3.085 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-COOL2021-P1006  
About • paper received ※ 04 November 2021       paper accepted ※ 22 November 2021       issue date ※ 10 December 2021  
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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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