Abstract
Contrary to the common belief that radiation damage varies slowly as the energy of the incident particle becomes relativistic, the authors argue that a strong energy dependence may occur, provided that the target material has very strong directional properties. In the case of a material with extremely strong directional properties, the damage may decrease as much as the inverse of the square of the energy. This effect arises from a general feature of the primary collision of the projectile with an atom, i.e. that the cross-section differential with respect to angle has a very strong energy dependence even at relativistic energies. Thus, the Rutherford differential cross-section, which gives a reasonable description of both elastic and inelastic processes over some important kinematic regions, decreases as the inverse of the square of the energy. The correlation between the energy dependence and directional properties of the target has been studied in the context of a simple model of radiation damage.