The Ultra-low energy Storage Ring (USR)

Antiprotons stored and cooled at low energies in a storage ring or at rest in traps are highly desirable for the investigation of a large number of basic questions on fundamental interactions, on the static structure of exotic antiprotonic atomic systems or of (radioactive) nuclei as well as on the time-dependent quantum dynamics of correlated systems.

The QUASAR Group has been leading the development of the USR which shall be installed at the Facility for Low-energy Antiproton and Ion Research (FLAIR) within the GSI future accelerator Facility for Antiproton and Ion Research (FAIR) since 2007.

The challenges for this project are:

  • Detailed beam dynamics studies for a novel energy-variable electrostatic cooler synchrotron;

  • Development of beyond state-of-the-art atomic physics experiments for collision studies with antiprotons and various atomic gas jet targets;

  • Design of an ion optics allowing for a combined slow/fast extraction of cooled beams even at lowest energies;

  • Development of innovative beam diagnostic methods.

Installed at a next-generation antiproton facility, this combination of a novel experimental facility on one hand and a rich atomic physics program with antiprotons on the other, provides an ideal base for a forefront long-term research program at FAIR. This work was supported by the Helmholtz Association and GSI under contract VH-NG-328 between 2007-2012, the DITANET project under contract 215080 and the Cockcroft Institute core grant. Studies were realized in close collaboration with and strong support from the Max-Planck-Institute for Nuclear Physics.


Currently involved QUASARs:

CarstenVolodymyr, Bianca, Javier


Selected Publications:


  • FLAIR Letter of Intent

  • FLAIR Technical Report(9 MB !)

  • E. Widmann, 'Plans for a Next-Generation Low-Energy Antiproton Facility', Phys. Scr. 72 (2005) C51-C56

  • C.P. Welsch, J. Ullrich, 'FLAIR A Facilty for Low-Energy Antiproton and Ion Research at GSI', Hyperfine Interactions, Hyperfine Interactions, 172 (1-3) 71-80 (2007)

  • C.P. Welsch, M. Grieser, J. Ullrich, A. Wolf, 'FLAIR Project at GSI', AIP Conf. Proc. 821 (2006), p.85-94


  • A. Papash, A. Smirnov and C.P. Welsch, 'Nonlinear and long-term beam dynamics in low energy storage rings', Phys. Rev. ST Accel. Beams 16, 060101 (2013) (e060101)

  • C.P. Welsch,  A. I. Papash. O. Gorda,  J. Harasimowicz, O. Karamyshev, G. Karamysheva, D. Newton, M. Panniello, M. Putignano, M. R. F. Siggel-King, A. Smirnov, 'Ultra-low energy storage ring at FLAIR', Hyperfine Interact (2012) 213:205–215 (10751-011-0460-z)

  • C.P. Welsch, M. Grieser, J. Ullrich, A. Wolf, 'Layout of the USR at FLAIR', Proc. Europ. Part. Acc. Conf., Edinburgh, Scotland (2006)

  • C.P. Welsch, M. Grieser, J. Ullrich, A. Wolf, 'An ultra-low-energy storage ring at FLAIR', NIM A 546 (2005) 405–417

  • C.P. Welsch, 'Einblicke in die Dynamik von Quantensystemen', Physik in unserer Zeit, 02/2005, p. 92-96

Beam Instrumentation

  • S. Aghiona, O. Ahlénc, C. Amslerd,..., J. Harasimovicz,..., A. Sosa,...,C.P. Welsch et al., 'Prospects for measuring the gravitational free-fall of antihydrogen with emulsion detectors', Journal of Instrumentation 8 P08013  (2013) (P08013)

  • J. Harasimowicz et al., 'Beam diagnostics for low energy beams', Phys. Rev. ST Accel. Beams 15, 122801 (2012) (e122801)

  • M. Panniello, K.U. Kühnel, A.I. Papash, J. Harasimowicz J, M. Putignano, M.R.F. Siggel-King, C.P. Welsch, 'Beam instrumentation for the Ultra-low energy Storage Ring (USR)', Hyperfine Interactions vol 213 p. 191-198 (2012) (012-0596-5)

  • J. Harasimowicz, L. Cosentino, P. Finocchiaro, A. Pappalardo, C.P. Welsch, 'Scintillating Screens Sensitivity and Resolution Studies for Low Energy, Low Intensity Beam Diagnostics', Rev. Sci.Instr. 81 (9) (2010)