Born Mar. 8, 1879, in Frankfurt am Main; died July 28, 1968, in Göttingen. German physicist and radiochemist.

Hahn studied at the Universities of Marburg and Munich and was a professor in Berlin from 1910 to 1934. In 1912 he became associated with the Kaiser Wilhelm Institute for Chemistry in Berlin, where he conducted research with L. Meitner until 1938. In 1928, Hahn became director of the institute. He was president of the Max Planck Society in the Federal Republic of Germany from 1946 to 1960 and honorary president after 1960. Harm’s main work was devoted to research on radioactivity. Together with Meitner, he discovered several isotopes and a new radioactive element, protactinium. In 1921 he observed for the first time the phenomenon of nuclear isomerism among natural radioactive elements. He used methods of radioactivity to determine the age of rock and the processes of the formation of crystals. In 1938, together with F. Strassmann, he discovered the fission of the uranium nucleus under the impact of neutrons. This discovery was the first step in the use of nuclear energy. Hahn received the Nobel Prize in 1945 and was a member of many world academies.