Range-Energy Relations of 10- to 250-kev Protons and Helium Ions in Various Gases

Abstract

An analyzed beam of ions was brought through a differential pumping system into a low-pressure gas stopping cell, where the data necessary to plot a Bragg curve were obtained with the aid of a double grid ionization chamber of variable transverse radius. It was found that the resulting ionization extrapolated ranges may be uniquely determined only if the ionization chamber radius is greater than the transverse radius of the ionization envelope of the beam in the stopping gas. The ionization extrapolated range-energy relations for slow protons and alpha particles were determined in various gases. These data are also expressed in terms of an empirical relation. The observed range-energy relations are compared with previous data where they exist.