Response of the radial action and the radial frequency to a time-dependent potential for orbit O7 (Table 1). For this orbit, the action shows a non-secular oscillation that decreases in amplitude as the rate of change of the potential decreases. The value of Ω_r changes significantly with time, and here there are also oscillations that become smaller as the change rate of the potential decreases. The period of the oscillations corresponds with the radial period. The evolution of J_r has been quite adiabatic because it oscillates around a limiting value, which is the starting value when the particles were released at pericentre.