Mass transfer and nuclear interaction times in deep inelastic U + U collisions

In heavy ion collisions at Coulomb barrier energies a dinuclear 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 U + U (Z = 184) collisions at the VAMOS spectrometer at GANIL at five beam energies in the interval (6.09 − 7.35)×A MeV. At 6.09×A MeV the Coulomb barrier is not reached at all mutual orientations of the deformed uranium nuclei. The spectrometer covered the angles (35 ± 5)°. We observed a massive transfer of nucleons resulting in reaction products far from the entrance channel. Only nuclei lighter than uranium were observed. The transfer was correlated with a large energy dissipation of up to several 100 MeV. Fig. 1 shows the total kinetic energy (TKE) in the exit channel as a function of the detected fragment mass for all beam energies.