Instantaneous coefficient of restitution in tray 1 computed from the averaged velocity profiles of all NanoRocksexperiment runs. The coefficient of restitution average remains around 0.89 independently from the current average collision speed, with a narrow distribution around the mean for collision speeds above 5 mm s⁻¹. For collision speeds at or below 5 mm s⁻¹, the width of the distribution of velocities increases significantly.