A measurement of drift velocities of electrons in xenon–methane mixtures

An apparatus is described to measure drift velocities of electrons in gas mixtures. Free electrons are liberated in the gas by laser ionization and the drift time is measured with a two-beam differential method. Drift velocities in various xenon–methane mixtures have been investigated systematically with a xenon content from 0% to 95% in steps of 5%. In addition, drift velocities of electrons in an argon–methane (90:10) mixture are given. The measured velocities are compared with predictions of the Magboltz code.