Phase dependence of electronic stopping in water, with emphasis on carbon ions

Determine the phase dependence of electronic stopping power for ion projectiles in water by establishing the differences between solid (ice), liquid, and gaseous H2O targets; in particular, characterize the electronic stopping behavior of carbon ions in water because of their importance for applications.

Background

Electronic stopping power in water is central to biological and medical applications, yet the database contains experimental values only for H, He, Li, and C projectiles, with particularly sparse coverage for carbon despite its relevance to therapy. The authors’ analysis of scaled stopping cross-sections indicates non-negligible phase-related differences below the stopping maximum and negligible differences at higher energies, highlighting the need for systematic phase-comparative measurements.

Recent measurements suggest potential deviations from semi-empirical predictions near the stopping maximum for carbon ions in liquid water, underscoring the need for independent experiments and theory to clarify phase effects and provide recommended values. The explicit statement flags unresolved questions about how solid, liquid, and gaseous phases of water influence ion stopping behavior.