Hans Geiger
Johannes Wilhelm Hans Geiger was a German experimental physicist. He is known as the inventor of the Geiger counter, a device used to detect ionizing radiation, and for carrying out the Rutherford scattering experiments, which led to the discovery of the atomic nucleus. He also performed the Bothe–Geiger coincidence experiment, which confirmed the conservation of energy in light-particle interactions.
He was the brother of meteorologist and climatologist Rudolf Geiger.
Biography
Early years
Johannes Wilhelm Geiger was born on 30 September 1882 in Neustadt an der Haardt, Germany, the son of Indologist Wilhelm Geiger, who was a professor at the University of Erlangen.In 1902, Geiger started studying physics and mathematics at the University of Erlangen, where he received his Ph.D. under Eilhard Wiedemann in 1906 with a thesis on electric discharge in gases.
After graduating, Geiger received a fellowship to the University of Manchester, where he worked as an assistant to Arthur Schuster. In 1907, after Schuster's retirement, Geiger began to work with his successor, Ernest Rutherford, and in 1908, along with Ernest Marsden, conducted the famous Geiger–Marsden experiment. This process allowed them to count alpha particles and led Rutherford to start thinking about the structure of the atom. He was elected a Member of the Manchester Literary and Philosophical Society on 29 November 1910.
In 1911, Geiger and John Mitchell Nuttall discovered the Geiger–Nuttall law and performed experiments that led to Rutherford's atomic model.
Middle years
In 1912, Geiger was named head of radiation research at the Physikalisch-Technische Reichsanstalt in Charlottenburg, where he worked with James Chadwick and Walther Bothe. Work was interrupted when Geiger served in the German military during World War I as an artillery officer from 1914 to 1918.In 1924, Geiger and Bothe carried out the Bothe–Geiger coincidence experiment that confirmed the Compton effect, which helped earn Arthur Compton the 1927 Nobel Prize in Physics. Bothe received the Nobel Prize in Physics for their experiment in 1954, after Geiger's death.
In 1925, Geiger began a teaching position at the University of Kiel. In 1928, Geiger and his student, Walther Müller, created the Geiger–Müller tube. This new device not only detected alpha particles, but also beta and gamma particles, and is the basis for the Geiger counter. Geiger was awarded the Hughes Medal in 1929 for this work.
In 1929, Geiger was appointed Professor of Physics and Director of Research at the University of Tübingen, where he made his first observations of a cosmic ray shower. In 1936, he took a position at Technische Hochschule Berlin, where he continued to research cosmic rays, nuclear fission, and artificial radiation until his death in 1945.
Later years
Beginning in 1939, following the discovery of nuclear fission, Geiger became a member of the Uranium Club, the German investigation of nuclear weapons during World War II. The group splintered in 1942 after its members came to believe that nuclear weapons would not play a significant role in ending the war.Although Geiger signed a petition against the Nazi government's interference with universities, he provided no support to colleague Hans Bethe when he was fired for being Jewish.
Geiger endured the Battle of Berlin and subsequent Soviet occupation in April/May 1945. A couple of months later he moved to Potsdam, where he died on 24 September 1945.