Gaseous ionization detectors
（重定向自Gaseous ionization detector）
![Plot of variation of ion pair current against applied voltage for a wire cylinder gaseous radiation detector.](/Images/godic/202501/14/Detector_regions3330.gif")
![Families of ionising radiation detectors](/Images/godic/202501/14/Detectors_summary_33330.png")
![Schematic diagram of ion chamber, showing drift of ions. Electrons typically drift 1000 times faster than positive ions due to their much smaller mass.[2]](/Images/godic/202501/14/Ion_chamber_operation3330.gif")
![The generation of discrete Townsend avalanches in a proportional counter.](/Images/godic/202501/14/Proportional_counter_avalanches3330.jpg")
Gaseous ionization detectors are radiation detection instruments used in particle physics to detect the presence of ionising particles, and in radiation protection applications to measure ionizing radiation.
They use the ionising effect of radiation upon a gas-filled sensor. If a particle has enough energy to ionize a gas atom or molecule, the resulting electrons and ions cause a current flow which can be measured.