1. Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel, Switzerland
2. LUTH, CNRS, Observatoire de Paris, Université Paris Diderot, 5 place Jules Janssen, F-92195 Meudon, France
3. GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, D-64291 Darmstadt, Germany
4. Instytut Fizyki Teoretycznej, Uniwersytet Wrocławski, pl. M. Borna 9, PL-50-204 Wrocław, Poland