CR distributions f_cr(p, μ) for the runs with monenergetic (left) and power-law (right) CRs at different times. The monenergetic CRs isotropize with time. For the power-law case, lower-energy CRs isotropize with time, unlike the higher-energy CRs. It is indicated with three white contours: 4πp²f_cr ≈ 1.6 × 10⁻³ (left), 6.2 × 10⁻⁵ (middle), 4 × 10⁻⁶ (right). The white dashed line marks ﹩p{{\prime} }_{{\rm{eff}}}\approx 9.3p{{\prime} }_{{\rm{\min }}}﹩ (Equation (20)), a cutoff above which the CRs do not isotropize effectively until saturation (﹩t\approx 10{\gamma }_{\,\rm{fast}\,}^{-1}﹩).