The difference in the energy ?E 2 of recoil atoms after collision when two types of atoms differ in their masses by a quantity ?M 2 is
2.
In linear cascades the set of recoils produced in the sample can be described as a sequence of recoil generations depending on how many collision steps have passed since the original collision : primary knock-on atoms ( PKA ), secondary knock-on atoms ( SKA ), tertiary knock-on atoms ( TKA ), etc . Since it is extremely unlikely that all energy would be transferred to a knock-on atom, each generation of recoil atoms has on average less energy than the previous, and eventually the knock-on atom energies go below the threshold displacement energy for damage production, at which point no more damage can be produced.
मोबाइल