Time evolution of the pitch angle θ (dotted black line) for particle orbits with initial pitch angles varying from 5° to 19.6°. Plot a) and b) show the pitch angle evolution for the two orbits with initial pitch angles smaller than the inital loss cone angle of 11.8°. Plots c), e), and g) show the full time pitch angle evolution of orbits with initial pitch angles of 12°, 15° and 19.6°, and d), f), and h) show blow-ups of the corresponding curves.