Hans Geiger

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Johannes ( Hans ) Wilhelm Geiger (September 30, 1882 – September 24, 1945) was a German physicist. He is perhaps best-known as the co-inventor of the Geiger counter, and for the Geiger-Marsden experiment which discovered the atomic nucleus.

Geiger was born at Neustadt-an-der-Haardt, Germany. He was one of five children born to Wilhelm Ludwig Geiger, a philosophy professor at the University of Erlangen.

In 1902 Geiger began to study physics and mathematics in Erlangen and later attained a doctorate in 1906. In 1907 he began work with Ernest Rutherford at the University of Manchester. Together they created the Geiger counter. (In 1928 Geiger and his student Walther Müller created an improved version of the Geiger counter.) In 1912 he became leader of the Physical-Technical Reichsanstalt in Berlin, 1925 professor in Kiel, 1929 in Tübingen, and from 1936 in Berlin. Geiger also worked with James Chadwick.

He discovered with John Mitchell Nuttall the Geiger-Nuttall law and performed experiments that led to Rutherford's atomic model. He was also a member of the Uranverein (Uranium Club) in Nazi Germany, the group of German physicists who, during World War II, worked on but failed to create the German atomic bomb. (How much this failure resulted from lack of scientific progress and how much from foot-dragging due to ethical concerns remains a lively debate even today.) His loyalty to the Nazi Party led him to betray his Jewish colleagues, many of whom had helped him in his research before he became a member of the Nazi Party.

Geiger died in Potsdam a few months after the war ended.