Ratio of the cumulative accelerated ions to cumulative swept-up ions. The solid blue line corresponds to protons, and the dotted red line to silicon considering sputtering as the main destruction mechanism for the dust grains. The calculation was carried out with the number of CRs or dust grains (η_CR = 10⁻⁵, and η_a ∼ 5 × 10⁻³ in order to get a silicon-proton ratio of ∼20) at the end of the Sedov-Taylor phase.