LABORATORI NAZIONALI DI LEGNARO
The quest for super-heavy elements (SHEs) has been intensively pursued for decades, even though the very large Coulomb energies involved make SHEs extremely unstable against fission and thus the cross-sections for residue formation always more challenging experimentally. It will be shown here how direct fission time measurements can be used as a powerful tool to investigate the stability of super-heavy elements, using the sensitivity of fission times on fission barrier heights. In a first experiment the 238U + Ni reaction at 6.62 MeV/u has been studied using reverse kinematics, and fragments arising from the fission of Z=120 nuclei have been isolated. The blocking patterns of these fragments evidence long fission time ( 10-17s), a time scale only compatible with compound nucleus formation, confirmed by their energy and angular distribution.

DATA: 04-11-2005