Helium ionization detector (HID) -- uses a radioactive source to produce helium ions, which in turn ionize the components
Helium | helium | ionization | Low-ionization nuclear emission-line region | Ionization | International Muon Ionization Cooling Experiment | Everhart-Thornley detector | Zeus (particle detector) | The Omega Seamaster, a deep diving watch. The second crown (at 10 o'clock) is a Helium release valve | Radar Detector | Penning ionization | Particle detector | particle detector | Negative air ionization therapy | Metal Detector | Metal detector | metal detector | infrared detector | High Resolution Fly's Eye Cosmic Ray Detector | helium release valve | Helium ionization detector | Helium (band) | Gas detector | Flame ionization detector | Electron ionization | Discharge ionization detector | Canny edge detector |