K^-1 amorphisation dose as a function of crystalline ice temperature for the present measurements (red filled symbols: triangle, Ni²⁶⁺; downward triangle, Ne⁶⁺; cross, Kr³³⁺; circle, Ni¹¹⁺; square, Ta²⁴⁺) and previous measurements following the evolution of the same ice feature (open symbols: downward triangle, 3 keV He⁺; diamond, 30 keV H⁺; square, 30 keV He⁺; circle, 60 keV Ar²⁺; upward triangle, 100 keV Ar⁺; see Table 1 in Famá et al. 2010). The purple star shows K^-1 for crystalline ice irradiated with FUV Lyman α photons, for comparison (Leto & Baratta 2003).