The Ranges of Ionizing Electrons in Helium

Abstract

The paper shows that a fourth power law for the absorption of ionizing electrons in helium represents experimental results only for initial energies greater than 250 electron volts. For initial energies less than 200 electron volts, the formula $x=\left(\frac{a}{c^2}\right)[cE-f+flog\mathrm{}(cE-f\left)\right]$ is deduced, where $x$ is the range of an electron of initial energy $E$ electron volts, and the remaining quantities are constants. The formula is in agreement with the available experimental evidence, and appears to be applicable, with suitable changes in the constants, to other gases.