helium ionization detector

in gas chromatography
https://doi.org/10.1351/goldbook.H02767
A weak beta source and a high potential raise the helium atom of the @[email protected] to a @[email protected] state. All other substances having an @[email protected] lower than \(18\ \text{eV}\) are ionized, and the current that results is used to measure the components. The detector is usually employed to measure inorganic compounds at concentrations between \(0.1\) and \(10\ \text{ppmv}\). It has a @[email protected] of about \(10^{2}\) but is somewhat @[email protected] and requires great care to ensure the helium purity and to eliminate all leaks in the system.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2191 [Terms] [Paper]