Suche nach langen Kernkontaktzeiten im dinuklearen System U+U

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In heavy ion collisions at Coulomb barrier energies a di-nuclear system (DNS) can be formed when the cores come into contact. This enables the exchange of nucleons which is usually accompanied by the dissipation of kinetic energy. During this time the nuclei stick together. We investigated the correlation between the number of exchanged nucleons, the energy dissipation and the nuclear contact time with the superheavy DNS 238U + 238U (Z=184) where the Coulomb repulsion plays a dominant role. We performed the measurements at different beam energies and found that the kinetic energy of the transfer products is independent of the beam energy. This means that the available kinetic energy is completely dissipated and the energy of the transfer products is only determined by their Coulomb barrier. Different theoretical approaches predict exceptionally long nuclear contact times of more than 5×10-21 s for a subset of these events.A direct experimental access to these interaction times we expect from experiments at the velocity filter SHIP at GSI. At SHIP the rotation of DNS in steps of 180° becomes "visible". This allows us to determine lower limits for the rotation time of the DNS and nuclear interaction time, respectively.