  We investigate dynamics of activated escape in periodically modulated
systems. The trajectories followed in escape form diffusion broadened tubes,
which are periodically repeated in time. We show that these tubes can be
directly observed and find their shape. Quantitatively, the tubes are
characterized by the distribution of trajectories that, after escape, pass
through a given point in phase space for a given modulation phase. This
distribution may display several peaks separated by the modulation period.
Analytical results agree with the results of simulations of a model Brownian
particle in a modulated potential.
