The operation of Geiger-Müller detectors are summarized below.
G-M Detector Summary
The voltage of a Geiger-Müller (G-M) detector is set so that any incident
radiation produces the same number of electrons.
As long as voltage remains in the G-M region, electron production is independent
of operating voltage and the initial number of electrons produced by the incident
The operation voltage causes a large number of ionizations to occur near the
central electrode as the electrons approach.
The large number of positive ions form a positive ion sheath which prevents
additional electrons from reaching the electrode.
A quenching gas is used in order to prevent a secondary pulse due to ionization
by the positive ions.