  Employing a quantal diffusion description based on the stochastic mean-field
(SMF) approach, we analyze the mass distribution of the primary fragments in
the collisions of ${}^{136} \text{Xe}+{}^{208} \text{Pb}$ system at the
bombarding energy $E_\text{c.m.} =526$~MeV. This quantal approach provides a
good description of the primary fragment distribution without any adjustable
parameter, including the effects of shell structure.
