Author: Winters, D.F.A.
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TUPPM2R1
 Laser cooling of bunched O5+ ion beams at the CSRe: investigation of coherent effect and extraction of momentum distribution from Schottky spectrum  
 
  • H.B. Wang, D.Y. Chen, Z. Huang, X. Ma, L.J. Mao, W.Q. Wen, J.X. Wu, J.C. Yang, Y.J. Yuan, S.F. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
  • M.H. Bussmann
    CASUS, Görlitz, Germany
  • D. Kiefer, T. Walther
    TU Darmstadt, Darmstadt, Germany
  • S. Klammes, D.F.A. Winters
    GSI, Darmstadt, Germany
  • M. Löser, M. Siebold
    HZDR, Dresden, Germany
  • U. Schramm
    Technische Universität Dresden, Dresden, Germany
  • D. Zhang
    Xidian University, Xi’an, People’s Republic of China
  
  Laser cooling of O5+ ion beams with an energy of 275.7 MeV/u was achieved at the storage ring CSRe in Lanzhou, China [1]. In the experiment, the momentum distribution was measured by the Schottky resonator. Besides, a multi-particle tracking method has been developed to simulate the Schottky spectra of bunched ion beams. We systematically studied the dependence of the Schottky power on the number of stored ions at different bunching and observation harmonics. The central peak is coherently enlarged only when the observation harmonic is an integer multiple of the bunching harmonic. The reason is that the randomness of the phase for each ion disappears at this condition, thus all ions coherently contribute to the Schottky power (Pcenter-N2). Therefore, the greatly enhanced central peak, caused by the "coherent effect", has been fully interpreted for the first time. Besides, we propose a new method to extract the momentum distribution from the Schottky spectrum of the bunched ion beams. Unlike the previously used methods [2], this is a very simple and precise way to obtain momentum distribution in real-time for bunched ion beams during beam cooling experiments.
[1] W.Q. Wen, Hyperfine Interact. 240, 45 (2019);
[2] M. Bussmann, Proceedings of COOL 2007, 226-229; K. Lasocha, PRAB 23 (2020) 062803; V. Balbekov, Proceedings of EPAC 2004, Lucerne, Switzerland. 		 
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TUPPM2R2
 Laser Cooling taken to the Extreme at the FAIR SIS100  
 
  • D.F.A. Winters, S. Klammes, T. Kühl, P.J. Spiller, T. Stöhlker
    GSI, Darmstadt, Germany
  • M.H. Bussmann
    CASUS, Görlitz, Germany
  • M.H. Bussmann, U. Schramm, M. Siebold
    HZDR, Dresden, Germany
  • J. Gumm, B. Langfeld, T. Walther
    TU Darmstadt, Darmstadt, Germany
  • V. Hannen, K. Ueberholz
    Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany
  • U. Schramm
    Technische Universität Dresden, Dresden, Germany
  • T. Stöhlker
    IOQ, Jena, Germany
  • T. Stöhlker
    HIJ, Jena, Germany
  • T. Walther
    HFHF, Frankfurt am Main, Germany
  
  Funding: We acknowledge the support by BMBF ErUM-FSP APPA for the laser systems (05P16ODFA1, 05P15RDFA1, 05P12RDRB2 and 05P09RDFA3) and the detector systems (05P19PMFA1), and by Helmholtz POF IV MT ARD (ST2).
The heavy-ion synchrotron SIS100 is the core machine of the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It will be capable to accelerate very intense beams of heavy ions up to highly relativistic velocities. Laser cooling of bunched ion beams was chosen to reduce the longitudinal momentum spread of the ions in the SIS100. A novel concept will be used, where laser beams from three complementary laser systems (cw and pulsed) will be overlapped in space, time and energy to interact simultaneously with a very broad ion velocity range in order to maximize the cooling efficiency. We will present this project and give an update of its current status. We will also give an overview of the laser and detector systems that will be used at the SIS100. 		 
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TUPPM2R3
 Laser Cooling of Stored Bunched Relativistic Carbon Ions at the ESR, using a Novel Tunable High Repetition Rate Pulsed Laser System  
 
  • S. Klammes, L.H.J. Bozyk, T. Kühl, W. Nörtershäuser, R.M. Sanchez Alarcon, P.J. Spiller, M. Steck, T. Stöhlker, D.F.A. Winters
    GSI, Darmstadt, Germany
  • M.H. Bussmann
    CASUS, Görlitz, Germany
  • M.H. Bussmann, U. Schramm, M. Siebold
    HZDR, Dresden, Germany
  • D.Y. Chen, Z. Huang, X. Ma, H.B. Wang, W.Q. Wen
    IMP/CAS, Lanzhou, People’s Republic of China
  • N. Eizenhöfer, M. Horst, B. Langfeld, W. Nörtershäuser, T. Walther
    TU Darmstadt, Darmstadt, Germany
  • V. Hannen, K. Ueberholz
    Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany
  • N. Kiefer
    Universität Kassel, Kassel, Germany
  • W. Nörtershäuser, T. Walther
    HFHF, Frankfurt am Main, Germany
  • U. Schramm
    TU Dresden, Dresden, Germany
  • T. Stöhlker
    IOQ, Jena, Germany
  • T. Stöhlker
    HIJ, Jena, Germany
  
  Funding: We acknowledge the support by BMBF ErUM-FSP APPA for the laser systems (05P16ODFA1, 05P15RDFA1, 05P12RDRB2 and 05P09RDFA3) and the detector systems (05P19PMFA1), and by Helmholtz POF IV MT ARD (ST2).
Laser cooling at storage rings has proven to be a powerful technique to obtain ion with a very small relative longitudinal momentum spread (1E-6 range). This contribution will give an overview of the principle and status of bunched beam laser cooling at the experimental storage ring ESR at GSI, Germany. Results from a recent laser cooling beamtime in May 2021 at the ESR will be presented, where broadband laser cooling of bunched relativistic C3+ ion beams was successfully demonstrated for the first time using a sophisticated pulsed UV laser system with a very high repetition rate (~ MHz), variable pulse durations (166 - 735 ps) and high UV power (> 250 mW). 		 
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THPOSRP19
 Simulation of Broadband Laser Cooling of Relativistic Ion Beams at the Csre  
 
  • D.Y. Chen, Z. Huang, X. Ma, L.J. Mao, H.B. Wang, W.Q. Wen, J.X. Wu, J.C. Yang, Y.J. Yuan, S.F. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
  • M.H. Bussmann
    CASUS, Görlitz, Germany
  • D. Kiefer, T. Walther
    TU Darmstadt, Darmstadt, Germany
  • S. Klammes, D.F.A. Winters
    GSI, Darmstadt, Germany
  • M. Löser, M. Siebold
    HZDR, Dresden, Germany
  • U. Schramm
    Technische Universität Dresden, Dresden, Germany
  • D. Zhang
    Xidian University, Xi’an, People’s Republic of China
  
  Laser cooling of a bunched relativistic O5+ ion beam with a cw laser has been demonstrated at the CSRe [1]. The relative momentum spread of the cooled beams has reached 2×10-6. But laser cooling does efficiently cool the ions only within a narrow velocity class due to the narrow linewidth of the cw laser, one thus needs to scan the laser frequency relative to the rf-frequency to cool all ions [2]. To extend the acceptance of the laser force, we are planning to utilize a pulsed laser that combines with the cw laser to achieve broadband laser cooling. The pulsed laser enables simultaneous interaction with a broad velocity classes ions and the cw laser can cool the ions to lower temperatures. It should be noted that laser cooling of relativistic C3+ ion beams using a pulsed laser was successfully investigated at the ESR recently [3]. To study the beam cooling procedures, simulations of the cooling dynamics under different conditions are being performed based on our newly developed simulation code [4]. Through simulations, the optimal conditions for achieving efficient beam cooling will be determined to guide the successful implementation of the broadband laser cooling experiments.
[1] W.Q. Wen et al., to be submitted.
[2] M. Bussmann et al., J. Phys: Conf. Ser. 88 (2007) 012043.
[3] S. Klammes et al., COOL2023 conference.
[4] D.Y. Chen et al., NIMA 1047 (2023) 167852. 		 
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