Hans Wilhelm Geiger German physicist who created a radioactive particle counter (Geiger counter) Date of Birth: 30.09.1882 Country: Germany

Biography of Hans Wilhelm Geiger

Hans Wilhelm Geiger was a German physicist who invented the Geiger counter, a device used to measure radioactivity. Born on September 30, 1882, in Neustadt, Germany, Geiger came from a family of philology professors. After completing his secondary education, he attended Erlangen University while also attending physics lectures at the universities of Munich and Tübingen.

Geiger successfully obtained his doctorate in 1906 from Erlangen University and was sent to work at the University of Manchester, where one of the most prestigious and advanced physics departments in Europe was located. There, he became the closest assistant and colleague of the renowned physicist Ernest Rutherford. In 1908, Geiger and Rutherford invented a device for counting individual charged particles, known as the Geiger counter, which registered the intensity of radioactive emissions. In 1928, Geiger further improved his invention in collaboration with the German physicist Walther Müller, resulting in the Geiger-Müller counter. This type of counter was used in experiments to determine the structure of atoms.

In the following years, Geiger conducted numerous experiments on the passage of alpha particles through thin films of various metals, discovering that a small number of particles were scattered at significant angles. These experiments played a crucial role in Rutherford's discovery of the atomic nucleus and the creation of a comprehensive model of the atom. During this period, Geiger, together with the English physicist Douglas McIntyre Nettel, formulated the empirical Geiger-Nettel law, which relates the constant of radioactive decay to the energy of alpha particles.

In 1912, Geiger was offered the position of heading a laboratory specifically built for his research on radioactivity at the Physical-Technical Institute in Berlin. Upon returning to Germany and assuming the leadership of the laboratory, Geiger continued his investigations into atomic structure. During World War I in 1914, he was called to serve in the German artillery headquarters. Although he did not participate in combat, frequent trips to the front adversely affected his health, and he suffered from rheumatism for the rest of his life. In 1918, Geiger returned to his work in the laboratory.

In 1925, he was appointed professor and director of the Physical Institute at Kiel University. Together with Walter Bothe, Geiger experimentally proved the validity of the conservation laws of energy and momentum in the elementary atomic process known as the Compton effect. From 1929 to 1936, he worked at the University of Tübingen, where he continued studying artificial radioactivity and nuclear decay. It was there that he first observed the flux of cosmic rays in a Wilson chamber, marking a significant milestone in the field. In 1936, Geiger became a professor at the Technical University of Berlin. However, by 1938, his health had significantly deteriorated due to rheumatism, and he rarely left his home. At the end of World War II, when the Red Army was fighting in Berlin, he and his family moved from the city to Potsdam.

Hans Wilhelm Geiger, a German experimental physicist and a member of the Berlin Academy of Sciences and the Leopoldina Academy, was awarded the D. Jussau Medal. He was married to Elizabeth Hefter, and they had three sons. Geiger passed away on September 24, 1945, in Potsdam.