Geiger counter

Gei·ger counter   (gī'gər)    n.  An instrument that detects and measures the intensity of radiation, such as particles from radioactive material, consisting of a Geiger tube and associated electronic equipment. Also called Geiger-Müller counter. [After Hans Wilhelm Geiger (1882-1945), German physicist.]

Geiger counter 

Main Entry: Gei·ger count·er
Pronunciation: 'gI-g&r-"kaun-t&r
Function: noun
: an instrument for detecting the presence and intensityof radiations (as cosmic rays or particles from a radioactive substance) by means of the ionizing effect on an enclosed gas which results in a pulse that is amplified and fed to a device giving avisible or audible indication
Geiger, Hans (Johannes) Wilhelm (1882–1945), and Müller /'m[ue]-l&r/, Walther (fl1928), German physicists. Geiger did significant research on atomic theory, radioactivity, and cosmic rays. He developed a number of techniques and instruments for the detection and counting ofindividual charged particles. With the British physicist Ernest Rutherford (1871–1937), he developed in 1908 the first radiation counter, an instrument that counted alpha particles. With the helpof Müller he introduced an improved version of the Geiger counter in 1928. The Geiger-Müller counter marked the introduction of modern electrical devices into radiation research.

Geiger counter Gei·ger counter (gī'gər)
n.
An instrument that measures the intensity of radiation by detecting radioactive particles as they cross a metal or glass tube filled with gas, causing ionization of the gas molecules and producing an electrical discharge. Also called Geiger-Müller counter.

Geiger counter   An electronic instrument that detects and measures nuclear radiation, such as x-rays or gamma rays. The Geiger counter consists of a gas-filled tube with a charged electrode connected to a counter. As radiation passes through the gas it ionizes atoms along its path. The ions are attracted to the charged electrode, creating pulses of electric current that are registered by the counter.