Radiation Damage and Displacement Energy

Since the recoil direction of the stmck atom is determined by the dynamics of the collision, it will be a random variable during real experiments. The directional dependence of Ed, coupled with the randomness of the initial directions of the stmck atom, imply that the notion of a sharp displacement threshold is oversimplified. In reality, there is a range of displacement energies for which a displacement may occur. A weighted average over the displacement directions leads to an average displacement energy, which is the value most typically used as Ed. Typical values of Ed are 16 eV for Si, 29 eV for Cu and 43 eV for Au. 

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