Long fission times of super-heavy compound nuclei

The blocking technique in single crystals is a direct method to investigate the presence of long fission time components. With a lead beam impinging on a germanium single crystal, we tried to produce compound nuclei (CN) with atomic number Z=114 at high excitation energy. Blocking patterns for reaction products are reconstructed with position sensitive detectors at 20 degrees relative to the beam direction. The Z and the energies of all products are measured with Delta E-E telescopes of the 4 pi INDRA array, so that all reaction channels are unambiguously identified. With this setup, we can reach long fission times (>10(-8)s) that can be associated with CN fissions. However, in contrast to previous experiments in which such long fission times could be measured for Z = 120 and 124, no hint of long lifetimes within our sensitivity limit for Z=114 was observed, which may be due to the neutron deficiency of the formed isotopes.