Author: Roßbach, J.
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MOPAM2R2
Cooling of Rare Isotope Beams in the ESR Storage Ring  
 
  • M. Steck, R. Hess, R. Joseph, S.A. Litvinov, B. Lorentz, C. Peschke, J. Roßbach, S. Wunderlich
    GSI, Darmstadt, Germany
 
  Beam cooling is the most important technique for the preparation of stored secondary beams in the ESR storage ring. The rare isotope beams are produced in a thick target by fragmentation of a heavy ion primary beam. The low intensity of the secondary beam can be increased by longitudinal accumulation schemes which use both stochastic and electron cooling of the injected beam. The conflict between the high energy of the heavy ion beam needed to produce highest intensities of rare isotopes and the request of some experiments for much lower energies can be resolved by deceleration of the secondary beam in the ESR. The efficiency of deceleration crucially depends on the low emittance and momentum spread of the beam when deceleration starts. Electron cooling at intermediate energies in the course of the deceleration and at the final energy is an additional asset to the goal of efficient deceleration to lowest energies and optimum conditions for experiments. The report gives an overview of various aspects of beam cooling in the endeavor to prepare highest beam quality and luminosity for experiments with stored secondary beams in the ESR.  
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WEPAM2R2
Heavy, Highly-charged Ions at GSI/FAIR Decelerated and Cooled  
 
  • F. Herfurth, Z. Andelkovic, S. Fedotova, W. Geithner, R. Hess, C. Krantz, M. Lestinsky, A. Reiter, J. Roßbach, S. Trotsenko, G. Vorobyev, B. Zhou
    GSI, Darmstadt, Germany
  • M. Horst, W. Nörtershäuser, S. Rausch
    TU Darmstadt, Darmstadt, Germany
  • N.S. Stallkamp
    IKF, Frankfurt am Main, Germany
 
  At GSI/FAIR heavy, highly charged ions for precision experiments are stripped at high energy and then slowed down in steps and cooled. Final deceleration to about 1 MeV/u is done in a dedicated low-energy storage ring. For this, the existing storage ring CRYRING, has been transferred from Stockholm to Darmstadt, refurbished and taken into operation. The CRYRING@ESR facility is in routine operation now providing ions for experiments either via the ESR but also from a local ECR ion source. Major challenges are the detection of weak and slow ion beams and the vacuum conditions. To get well below 1 MeV/u ion beam energy, a linear decelerator in conjunction with a Penning trap, HITRAP, has been built and partly commissioned. After deceleration to only a few eV/nucleon electron cooling and resistive cooling shall be applied. Electron cooling is relatively unexplored in Penning traps. However, a first interaction of simultaneously stored electrons with highly-charged ions has been detected in the HITRAP cooling trap recently. Further investigation and especially an improved alignment eventually lead to first signs of electron cooling of highly-charged ions in a Penning trap.  
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FRPAM1R1
Electron Cooling of Low-Energy Ion Beams in CRYRING@ESR  
 
  • C. Krantz, Z. Andelkovic, C. Dimopoulou, S. Fedotova, W. Geithner, F. Herfurth, R. Hess, M. Lestinsky, E. Menz, K. Mohr, A. Reiter, J. Roßbach, R.M. Sanchez Alarcon, G. Vorobyev
    GSI, Darmstadt, Germany
  • K. Mohr, W. Nörtershäuser
    TU Darmstadt, Darmstadt, Germany
 
  Within the CRYRING@ESR project, the heavy-ion storage ring CRYRING has been transferred from Stockholm to Darmstadt. It complements the Experimental Storage Ring (ESR) of GSI/FAIR by a machine optimized for low ion energies. CRYRING@ESR can store the full spectrum of highly-charged heavy ions available from the UNILAC/SIS18 accelerator chain after deceleration in ESR, with the option to decelerate even further in CRYRING itself. Electron cooling in both rings is an essential part of beam preparation at CRYRING@ESR. In a complementary stand-alone mode, CRYRING@ESR can operate with ions in low charge states, injected from an independent low-energy linac. This extends the experimental possibilities available at GSI/FAIR, but comes with new challenges with respect to electron cooling. Singly- or weakly-charged ions are often limited to very low storage velocities, capped by the maximum rigidity of the bending magnets. With ions that slow, interaction of the electron space-charge with the dispersive ring optics can easily lead to instabilities in the cooled beam. We present and discuss our experience with low-energy electron cooling from the first years of CRYRING@ESR operation.  
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