Result of a toy model wave-particle resonance after two gyration periods with a wave amplitude of δB/B₀ = 0.1. The pitch-angle scattering is presented in terms of change in Δμ dependent on the particles intial μ₀. Each dot represents an individual particle. The theoretical, quasilinear prediction of the maximal change in μ by Eq. (32) deviates clearly from the observed scattering. This type of plot is hereafter denoted as scatter plot.