# Ionisation

The radiation on passing through the material causes electrons to be stripped from some of the atoms in the absorbing material. The process is called .

Energy is transferred to the absorber during the ionisation process. For a given thickness of absorber, alpha radiation produces most ionisation, beta next and gamma least.

A way of expressing the radiation dose received from different sources is in terms of a quantity called equivalent dose. Equivalent dose is measured in sieverts $$(Sv)$$. A dose of one sievert from an alpha radiation source, for example, is equivalent to a dose of one sievert from a beta radiation source or any other source of radiation.