  We report on a novel experimental approach for studying the dissipative
spreading of collective motion in a meta-stable nuclear system, using, for the
first time, highly fissile nuclei with spherical shape. This was achieved by
fragmentation of 45 radioactive heavy-ion beams at GSI, Darmstadt. The use of
inverse kinematics and a dedicated experimental set-up allowed for the
identification in atomic number of both fission fragments. From the width of
their charge distributions, a transient time of (3.3 +/- 0.7) 10-21 s is
deduced for initially spherical nuclei.
