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)