1. Institut de Physique Nucléaire, Université Paris-Sud, IN2P3-CNRS, F-91406 Orsay, France
2. DPTA/SPN-CEA Bruyères, 91680 Bruyères-le-Châtel Cedex 12, France
3. Phys. Dep., Faculty of Science, University of Zagreb, Bijenička 32, 10000 Zagreb, Croatia
4. Department of Physics, Florida State University, Tallahassee, FL-32306, USA
5. GANIL (CEA/DSM-CNRS/IN2P3), BP 5027, 14076 Caen Cedex, France