High depth resolution Rutherford backscattering-channelling has been employed to assess the depth of damage and the increase in total damage with increasing ion fluence over the range 1014-1016ions cm−2for 5 keV A+implants into Si conducted under low flux density and UHV conditions. It is shown that damage-depth estimates for zero fluence conditions are similar to theoretical predictions and that the increasing damaged (amorphised layer) depth with increasing fluence is the result of continuing damage accumulation deeper in the Si.