Mean-free path ﹩{\lambda }_{r}﹩ vs. maximum intensity of particle release (top panel) and time delay with respect to the preceding solar release (bottom panel) for the four events under study. The solid line shows a linear fit. The horizontal dotted lines mark the resolution of the grid in ﹩{\lambda }_{r}﹩. Error bars show an estimate of the uncertainty in ﹩{\lambda }_{r}﹩.