1. Flerov Laboratory of Nuclear Research, JINR, 141980 Dubna, Russia
2. Universite Libre de Bruxelles, 1050 Bruxelles, Belgium
3. Institut de Recherches Subatomiques, F-67037 Strasbourg Cedex, France
4. Dipartimento di Fisica dell' Universita di Messina 98166 Messina, Italy
5. University of California, Lawrence Livermore National Laboratory, Livermore, California 94551, USA