A proportional counter is an ionising particle detector. Its operation is based on the ionisation produced in particles by an intense electric field passing through the gaseous detection volume. Both radiation types can be simultaneously measured taking into account that, by passing through a material medium, an alpha particle produces a higher specific ionisation than a beta particle of equal energy.

This gas-flow detector allows to measure low-alpha / low-beta-activity samples, that is, is used to determine the rate of total alpha and beta emissions.

1. Environment
2. Radiological surveillance