He3Isotopic Abundance

Abstract

The isotopic abundance of ${\mathrm{He}}^3$ in one sample each of "well" helium and "atmospheric" helium has been measured by detecting the ${\mathrm{He}}^3\mathrm{}(n,p)\mathrm{}{\mathrm{H}}^3$ disintegrations induced by thermal neutrons. The helium gas was put into a proportional counter, the disintegration rate compared to that with nitrogen in the counter, and the ${\mathrm{He}}^3$ content deduced from the known ratio of the ${\mathrm{He}}^3$ and N disintegration cross sections.