OCR Text |
Show Geiger Counter Invented in 1920; Operation Simple In 1920 a couple of research rs developed an instrument for measuring radioactive radiation. Today the Instrument is embodied In a compact unit and Is known as the gelgcr counter familiar to every uranium hunter on the Colorado Plateau. Heart of the Instrument is the Gclger-Mueller tube, developed by W. Gciger and M. Mueller. The tube utilizes two of the properties of beta and gamma radiation: the ability of gamma rays and beta particles to ionize a gas or to make a gas conductive to electricity. Inside the tube commonly found in most detectors is a thin wire sealed within the evacuated tube, running parallel to the surface of the metal and electrically insulated from it. The tube Is connected in scries with a battery and earphones, or a neon indicator, and the voltage is ad-Justed so that the tube will not conduct except when brought Into the field of radiation. When the penetrating radioactive particles or rays enter the tube they ionize the gas, and an electric current is set up which causes the earphones to "click" or the neon lamp to flicker. When the earphones "click" once or the neon tube flickers only once, a ray or particle has passed thru the tube. Of course, larger getger counters are equipped with meters to measure the amount of radiation and other devices to provide users with average counts. Alpha rays are absorbed by most materials, and the outer wall of the Reiger counter absorbs them so that they are not recorded. |