On the gas–solid difference in stopping power for low energy ions

Abstract

In an earlier paper we claimed that the well-known gas–solid difference in high energy mass stopping powers persists down to low energy; this claim was essentially based on stopping powers for N ions. We now re-investigate this claim using many more experimental data, comparing them to the recent stopping power table of ICRU Report 73 which has no gas–solid difference built in, and by using our statistical analysis program. We find that, at a specific energy of 25 keV/n, the average gas–solid difference amounts to −40% for N ions and to −48% for all ions from 3Li to 18Ar taken together, the stopping power for gas being lower. It appears therefore that the agreement between experiment and theory could be improved by taking this difference into account.