Abstract
In a crossed-beam experiment absolute cross sections for ionisation by electron impact are measured for the processes Mg+e to Mg++2e and Mg+e to Mg2++3e. The Mg+ and Mg2+ ions are separated by a time-of-flight method. Electron energies are varied between 30 eV and 280 eV. Cross sections at the maximum of the ionisation functions are 7.8*10-16 cm2 (Mg+) and 9*10-18 cm2 (Mg2+).