1. IPHC, Université de Strasbourg, F-67037 Strasbourg, France
2. CNRS, UMR7178, F-67037 Strasbourg, France
3. USIAS, F-67083 Strasbourg, France
4. Department of Physics, University of York, Heslington, York YO10 5DD, U.K.
5. Department of Physics, University of Surrey, Guildford GU2 7XH, U.K.
6. Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
7. IPN Orsay, UMR8608, IN2P3-CNRS, Université Paris Sud 11, 91406 Orsay, France
8. GANIL CEA/DSM-CNRS/IN2P3 Caen, France