The range of fast heavy particles in solids is determined by a sensitive method (removal of thin surface-layers by low energy sputtering) . The range distributions in various directions of copper single crystals are measured using Kr 85 ions of energies between 25 and 150 keV. The mean range in fits the general range vs. energy relation given by LINDHARD and SCHARFF. In and especially in , the range distributions show long tails which increase the mean penetration of the krypton ions in these directions. These “super ranges” are caused by so-called stenons, i. e. ions which move in the structural “channels” of the f.c.c. lattice.