Fast-Fission Phenomenon in Time-Dependent Hartree-Fock Studies ofPb208+Ge74Collisions

Fast-fission phenomenon is apparent in time-dependent Hartree-Fock calculations of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$+${}_{}{}^{74}{}_{}{}^{}\mathrm{Ge}$ collisions at $E_{\mathrm{lab}}\left(\mathrm{Pb}\right)=1600\mathrm{}$ MeV for a range of entrance-channel angular momenta between fusion and deep-inelastic processes. A long-lived composite system is formed which eventually leads to binary fragmentation with appreciable mass and charge drift and energy loss. The time scales are shorter than those for fusion, yet far too long compared to deep-inelastic processes. A cross section ${\sigma }_{\mathrm{ff}}=295\mathrm{}\pm 75$ mb is estimated.