Johannes (Hans) Wilhelm (Gengar) 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 the Indologist Wilhelm Ludwig Geiger, who was professor at the University of Erlangen.
In 1902 Geiger started studying physics and mathematics in University of Erlangen and was awarded a doctorate in 1906. In 1907 he began work with Ernest Rutherford at the University of Manchester and in 1909, along with Ernest Marsden, conducted the famous Geiger-Marsden experiment called the 'gold foil experiment'. Together they created the Geiger counter. In 1911 Geiger and John Mitchell Nuttall discovered the Geiger-Nuttall law (or rule) and performed experiments that led to Rutherford's atomic model. In 1928 Geiger and his student Walther Müller created an improved version of the Geiger counter, the Geiger-Müller counter. Geiger also worked with James Chadwick.
In 1912 he became leader of the Physical-Technical Reichsanstalt in Berlin, 1925 professor in Kiel, 1929 in Tübingen, and from 1936 in Berlin.
He was a member of the Uranium Club, which was working on an atomic bomb for Nazi Germany.
Geiger died in Potsdam, Germany a few months after World War II ended.
AKA Johannes Wilhelm Geiger
Birthplace: Neustadt an der Haardt, Germany
Location of death: Potsdam, Germany
Cause of death: unspecified
Remains: Buried, Neuer Friedhof, Potsdam, Germany
Race or Ethnicity: White
Executive summary: Co-Inventor of the Geiger Counter
Military service: German Army (WWI, artillery officer)
After schooling at Munich and Erlangen Geiger became an assistant to Ernest Rutherford at the University of Manchester. There, he devised equipment to count alpha particles. In 1928 he co-invented the Geiger Counter, a much more portable machine to count alpha particles, with fellow physicist Walther Müller. He served as an artillery officer during WWI, and during WWII participated in the German attempt to build an atomic bomb.
Father: Wilhelm Ludwig Geiger (philology professor)
High School: Erlangen Gymnasium (1901)
University: University of Munich
University: PhD, University of Erlangen (1906)
Scholar: University of Manchester (1907-12)
Scholar: Imperial Physical Technical Institute, Berlin (1912-25)
Professor: University of Kiel (1925-29)
Professor: University of Tübingen (1929-36)
Professor: Technische Hochschule, Berlin (1936-45)