The Damage Cascade

Abstract

In our discussion of cascade development, no consideration was given to the spatial arrangement of displaced atoms. We assumed that every Frenkel pair created was preserved and that no annihilation occurred. However, the spatial arrangement of these Frenkel pairs is crucial in determining the number that survive annihilation or immobilization by clustering. In order to understand what the damaged region looks like, we need to know whether the displacements are concentrated or distributed. A helpful tool in this regard is the mean free path for displacement collisions, i.e., collisions in which the energy transferred is greater than E _d. This will tell us how far apart the displacements occur and hence the separation distance between Frenkel pairs.

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