Professor Hans Geiger, c mid-20th century

Hans Geiger, born 30 September 1882, died 24 September 1945, was a German nuclear physicist. He is best known for inventing the Geiger counter, a device to detect ionizing radiation. He is also known for carrying out Rutherford scattering experiments, through which the discovery of the atomic nucleus was made. Geiger studied at the University of Erlangen and obtained his doctorate in 1906. He received a scholarship to Manchester, and worked there with Ernest Rutherford. He moved back to Germany to work, but was interrupted by WWI, with Geiger serving from 1914 to 1918. In 1920, Geiger married Elizabeth Heffter and they had three sons. From 1939, Geiger was a member of the Uranium Club, the German investigation of nuclear weapons during WWII. Although Geiger signed petitions against Nazi government interference with universities, Deutsche Physick, he did not support his Jewish colleagues directly after they were fired. Geiger was in Berlin during the Battle of Berlin, and the Soviet occupation in April to May 1945. Geiger moved to Potsdam in 1945, dying there due to complications from chronic rheumatism, age 62.