The FRS Ion Catcher - A facility for high-precision experiments with stopped projectile and fission fragments

W. R. Plaß, T. Dickel, S. Purushothaman, P. Dendooven, H. Geissel, J. Ebert, E. Haettner, C. Jesch, M. Ranjan, M. P. Reiter, H. Weick, F. Amjad, S. Ayet, M. Diwisch, A. Estrade, F. Farinon, F. Greiner, N. Kalantar-Nayestanaki, R. Knöbel, J. KurcewiczJ. Lang, I. Moore, I. Mukha, C. Nociforo, M. Petrick, M. Pfützner, S. Pietri, A. Prochazka, A. K. Rink, S. Rinta-Antila, D. Schäfer, C. Scheidenberger, M. Takechi, Y. K. Tanaka, J. S. Winfield, M. I. Yavor

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


At the FRS Ion Catcher at GSI, projectile and fission fragments are produced at relativistic energies, separated in-flight, range-focused, slowed down and thermalized in a cryogenic stopping cell. A multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) is used to perform direct mass measurements and to provide an isobarically clean beam for further experiments, such as mass-selected decay spectroscopy. A versatile RF quadrupole transport and diagnostics unit guides the ions from the stopping cell to the MR-TOF-MS, provides differential pumping, ion identification and includes reference ion sources. The FRS Ion Catcher serves as a test facility for the Low-Energy Branch of the Super-FRS at the Facility for Antiproton and Ion Research (FAIR), where the cryogenic stopping cell and the MR-TOF-MS will be key devices for the research with stopped projectile and fission fragments that will be performed with the experiments MATS and LaSpec. Off-line tests of the stopping cell yield a combined ion survival and extraction efficiency for 219Rn ions of about 30% and an extraction time of about 25 ms. The stopping cell and the MR-TOF-MS were commissioned on-line as part of the FRS Ion Catcher. For the first time, a stopping cell for exotic nuclei was operated on-line at cryogenic temperatures. Using a gas density almost two times higher than ever reached before for a stopping cell with RF ion repelling structures, various 238U projectile fragments were thermalized and extracted with very high efficiency. Direct mass measurements of projectile fragments were performed with the MR-TOF-MS, among them the nuclide 213Rn with a half-life of 19.5 ms only.

Original languageEnglish
Pages (from-to)457-462
Number of pages6
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Issue numberPART B
StatePublished - Dec 15 2013


  • Cryogenic gas-filled stopping cell
  • Direct mass measurement
  • Exotic nuclei
  • Extraction time
  • Multiple-reflection time-of-flight mass spectrometer
  • Projectile fragmentation


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