Hans Geiger

(Neustadt, Germany, 1882-Potsdam, Germany 1945)

German physicist, inventor of the counter to detect and measure the presence of radioactive particles that bears his name. He received his doctorate in 1906 from the University of Erlangen. Between 1907 and 1912 he collaborated with E. Rutherford at the University of Manchester. In 1912, already in Germany, he held the position of director of the German Physical Laboratory and in 1925 that of professor at the University of Kiel.

During his stay in the United Kingdom, he built the first version of the particle detector and counter that bears his name, essential in the identification of the nature of alpha particles as helium nuclei by Rutherford and himself. The first Geiger counter consisted of a cylinder filled with gas at reduced pressure and an insulated wire across its axis, establishing a high potential difference between the two. The passage of a particle through the counter produces a short discharge, which is increased by the secondary ionization that occurs by virtue of the collisions; these discharges were recorded mechanically.

Its meter basically consists of a cylindrical figure filled with gas, a fluid that is subjected to the action of electrodes, in which a very noticeable difference in charge is established. When an alpha-type particle appears, the gas tends to ionize and cause discharges lasting a moment, in addition to which the electrical potential decreases from which a measurement can be taken.

Likewise, it creates a law that declares that within a radioactive family, the path of a certain particle is related to the isotope and its half-life.

Thus, it also detects the main characteristics that the effect known as Compton entails. Then Geiger decides to join another university, the same one called Kiel and in which he teaches physics.

It is highlighted in his biography that in this place he has contact with Walther Müller and with his support he manages to add improvements to the design of his invention, the counter. With all this work, the invention acquires the ability to reveal different types of radiation.

This counter detects alpha radioactivity, as well as gamma and beta, a reason that leads the counter to transcend history with the surnames of both, mainly Geiger.

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