Distribution of the temperature ratio and the differential velocity as a function of solar wind speed and collisional age. (a): Probability distribution of the proton velocity shows that our dataset during encounter 10 includes a similar amount of fast and slow solar wind with velocities greater and smaller than 400 km s⁻¹, respectively. (b): Distribution of T_α/T_p for different solar wind speeds. Yellow, pink, and orange shaded regions show the T_α/T_p of the combined, slow and fast solar wind, respectively. (d): Distribution of T_α/T_p for all, small, and large Coulomb numbers are shown in yellow, red, and green shaded regions, respectively. The distribution of differential velocity over Alfvén speed is plotted based on different solar wind speeds and Coulomb numbers in panels c and e. Error bars are shown in all panels.