  The process of formation of the participant system in heavy-ion collisions is
investigated in the framework of a simplified analytic Glauber-like model,
which is based on the relativistic Boltzmann transport equation. The key point
lies in the time-dependent partition of the nucleon system into two groups:
nucleons, which did not take part in any interaction before a given time and
nucleons, which already have interacted. In the framework of the proposed model
we introduce a natural energy-dependent temporal scale $t_c$, which allows us
to remove all dependencies of the model on the collision energy except for the
energy dependence of the nucleon-nucleon cross-section. By investigating the
time dependence of the total number of participants we conclude that the
formation process of the participant system becomes complete at $t\simeq1.5
t_c$. Time dependencies of participant total angular momentum and vorticity are
also considered and used to describe the emergence of rotation in the reaction
plane.
