Author: Geithner, W.
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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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