English: Image sequence of a collision cascade in the heat spike regime produced by a 30 keV Xe ion impacting on Au under channeling conditions, obtained by molecular dynamics computer simulations The image shows a cross section of two atomic layers in the middle of a threedimensional simulation cell. Each sphere illustrates the position of an atom, and the colors show the kinetic energy of each atom as indicated by the scale on the right. The atom size is also proportional to the energy, so that higher-energy atoms are somewhat larger.