Geometric collision probability (top), average impact velocity (middle), and the geometric part of the collision rate (bottom) in the high-excitation simulation discussed in Sect. 4.2, as a function of the eccentricity e_t and the inclination i_t of target particles colliding with projectiles with uniform distributions of eccentricity and inclination from 0 to e_p,max = 0.2 and i_p,max = 0.1, respectively, calculated using the Monte Carlo code described in Sect. 3.1.2. Both targets and projectiles have uniform distributions of semi-major axis with a_min = 36 au and a_max = 44 au, as in our disc models. In these simulations, we use 10⁵ particles in each Monte Carlo population. The collision rate is maximised for high eccentricities and low inclinations of the target. See Sect. 4.2.