Is there anyone who has not heard of the Geiger Counter? Almost every child knows what it is used for. In the atomic era, the Geiger-Müller Counter, as it is officially known, is an indispensable piece of equipment for all radiation physicists. Its invention in 1929 achieved fame for Geiger beyond the realms of physics. Albert Einstein dubbed the measuring device “humankind’s most sensitive organ”.
When he took over the directorship of the Physics Institute at Technische Hochschule Berlin in 1936 in the midst of turbulent times, Geiger could already look back on a distinguished international career. He was born into an intellectual middle-class family in Neustadt/Weinstraße in 1882 and grew up in Munich and Erlangen, where his father was university professor of Persian studies and Indology. He attended the Fridericianum in Erlangen and completed his schooling there in 1901. During his school years, Geiger already displayed an interest in mathematics and natural sciences. In the fall of 1901, he started studying mathematics and physics at the university in Erlangen.
Through his teacher, Professor Eilhard Wiedemann, he fell under the spell of experimental physics, which was to become his main area of scientific endeavor throughout his life. In 1904 he switched to Munich for one semester, where he attended lectures at the Technical University. Shortly thereafter he took his first teaching examination and completed his degree in 1906 with a dissertation on radioactive emissions. Wiedemann, who was also his doctoral supervisor, obtained him a position as assistant to Professor Arthur Schuster at the University of Manchester.
In 1907, Nobel Prize laureate Ernest Rutherford became head of the physics institute in Manchester. Rutherford’s cooperative approach to research greatly impressed Geiger and Rutherford was in turn no less impressed by Geiger’s talents as an experimental physicist. In 1908, they jointly published a work on electrical counting methods of alpha particles. In the same year Geiger was able to prove the statistical nature of radioactive decay. While in Manchester, Geiger also undertook teaching duties. Regarding his time in England, he wrote to Max von Laue: “If I have been able to do something for our physics, than I owe this more than anything to the good fortune of having come into contact with Rutherford at an early stage of my life.”
In 1912, Geiger took up a professorship at the Physikalisch-Technische Reichsanstalt (PTR) in Berlin, where he was head of the radioactivity laboratory. He also lectured at Technische Hochschule zu Berlin. During the First World War he served as an officer.
He resumed his work at PTR in 1919. In 1920, he married Elisabeth Heffter, with whom he had three sons. He completed his Habilitation in Berlin in1924 with a work on alpha emissions. His international reputation as an experimental physicist established, he was able to take up a professorship at Kiel University in 1925. His work with his assistant Walther Müller (1905-1979) led to the invention of the Gieger-Müller counter. In August 1929, he took up the chair of experimental physics in Tübingen. He was an outstanding teacher, capable of enthusing his students. His lectures were accessible, his manner of speaking clear, convincing, and often amusing. His students dubbed him “Varieté-Geiger” (Geiger the Cabaret Artist)
In 1933 the politics of the Nazis began to intrude into the academic life of Geiger. He was appointed director of the Institute of Physics at Technische Hochschule Berlin in 1936: After the outbreak of war, he was employed to conduct research into nuclear fission using uranium. Resignation and sickness marked this period of his life. Hans Geiger died on 24 September 1945 in Potsdam.