  Fissile nuclei with small shape distortion relative to the ground-state
deformation and with low angular momentum were produced in peripheral heavy-ion
collisions. Under the conditions of small shape distortions and low angular
momentum, the theoretical description of the fission process can be
considerably simplified, and the relevant information on dissipation can be
better extracted than in conventional experiments based on fusion-fission
reactions. In addition, this experimental approach induces very high excitation
energies, a condition necessary to observe transient effects. The experimental
data were taken at GSI using a set-up especially conceived for fission studies
in inverse kinematics. This set-up allowed determining three observables whose
sensitivity to dissipation was investigated for the first time: the total
fission cross sections of 238U at 1 A GeV as a function of the target mass,
and, for the reaction of 238U at 1 A GeV on a (CH2)n target, the partial
fission cross sections and the partial charge distributions of the fission
fragments. The comparison of the new experimental data with a reaction code
adapted to the conditions of the reactions investigated leads to clear
conclusions on the strength of dissipation at small deformation where the
existing results are rather contradictory.
