Background

Hans Geiger was born on September 30, 1882, in Neustadt an der Weinstraße, Rhineland-Palatinate, Germany. He was the eldest of the five children of Wilhelm Ludwig Geiger, professor of philology at Erlangen from 1891 to 1920. His only brother, Rudolf, became professor of meteorology at Munich.

Education

Geiger passed his Abitur at the Erlangen Gymnasium in 1901. After a brief period of military service he studied physics both at Munich and at Erlangen. He took his preliminary examination in 1904 and then began his research under Eilhard Wiedemann. In July 1906 Geiger defended his inaugural dissertation and received his doctorate from the University of Erlangen.

Career

Geiger moved to Manchester University in England to join its esteemed physics department in 1906. At first he was an assistant to its head, Arthur Schuster, an expert on gas ionization. When Schuster departed in 1907, Geiger continued his research with Schuster's successor, Ernest Rutherford, and the young physicist Ernest Marsden.

In addition to supervising the research students working at the lab, Geiger began a series of experiments with Rutherford on radioactive emissions, based on Rutherford's detection of the emission of alpha particles from radioactive substances. Together with Marsden he conducted the famous Geiger-Marsden experiment. This process allowed them to count alpha particles and led to Rutherford's winning the 1908 Nobel Prize in Chemistry.

In 1912 Geiger gave his name to the Geiger-Nuttal law, which states that radioactive atoms with short half-lives emit alpha particles at high speed. He later revised it, and in 1928, a new theory by George Gamow and other physicists made it redundant. Also in 1912 Geiger returned to Germany to take up a post as director of the new Laboratory for Radioactivity at the Physikalisch-Technische Reichsanstalt in Berlin, where he invented an instrument for measuring not only alpha particles but beta rays and other types of radiation as well.

Geiger's research was broadened the following year with the arrival at the laboratory of James Chadwick and Walter Bothe, two distinguished nuclear physicists. With the latter, Geiger formed what would be a long and fruitful professional association, investigating various aspects of radioactive particles together. However, their work was interrupted by the outbreak of the First World War. Enlisted with the German troops, Geiger fought as an artillery officer opposite many of his old colleague.

Geiger moved from the Reichsanstalt in 1925 to become professor of physics at the University of Kiel. His responsibilities included teaching students and guiding a sizable research team. He also found time to develop, with Walther Mueller, the instrument with which his name is most often associated: the Geiger-Mueller counter, commonly referred to as the Geiger counter. Electrically detecting and counting alpha particles, the counter can locate a speeding particle within about one centimeter in space and to within a hundred-millionth second in time. It consists of a small metal container with an electrically insulated wire at its heart to which a potential of about 1000 volts is applied. In 1925, Geiger used his counter to confirm the Compton effect, that is, the scattering of X rays, which settled the existence of light quantum, or packets of energy.

Geiger left Kiel for the University of Tubingen in October of 1929 to serve as professor of physics and director of research at its physics institute. Installed at the Institute, Geiger worked tirelessly to increase the Geiger counter's speed and sensitivity. As a result of his efforts, he was able to discover simultaneous bursts of radiation called cosmic-ray showers, and concentrated on their study for the remainder of his career.

Geiger returned to Berlin in 1936 upon being offered the chair of physics at the Technische Hochschule. His upgrading of the counter and his work on cosmic rays continued. He was also busy leading a team of nuclear physicists researching artificial radioactivity and the byproducts of nuclear fission. Also in 1936 Geiger took over editorship of the journal Zeitschrift fur Physik, a post he maintained until his death.

Geiger continued working at the Technische Hochschule through the war, although toward the latter part he was increasingly absent, confined to bed with rheumatism. He had only just started to show signs of improvement in his health when his home near Babelsberg was occupied in June of 1945. Suffering badly, Geiger was forced to flee and seek refuge in Potsdam, where he died.

Achievements

• Hans Geiger was an eminent physicist. He is best known as the co-inventor of the detector component of the Geiger counter and for the Geiger-Marsden experiment which discovered the atomic nucleus. He was awarded the Hughes Medal by the Royal Society in 1929 for his invention and development of methods of counting alpha and beta particles and the Duddell Medal by the Physical Society in 1938 for his contributions to scientific instrumentation.

Works

More photos

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  • Messmethoden Auf Dem Gebiete Der Radioaktivitat 1920
  • Practical Measurements in Radio-Activity 1912

Politics

Geiger made a rare excursion into politics, prompted by the rise to power in Germany of Adolf Hitler's National Socialist Party. The Nazis sought to harness physics to their ends and engage the country's scientists in work that would benefit the Third Reich. Geiger and many other prominent physicists were appalled by the specter of political interference in their work by the Nazis. Together with Werner Karl Heisenberg and Max Wien, Geiger composed a position paper representing the views of most physicists, whether theoretical, experimental, or technical. As these men were politically conservative, their decision to oppose the National Socialists was taken seriously, and seventy-five of Germany's most notable physicists put their names to the Heisenberg-Wien-Geiger Memorandum. It was presented to the Reich Education Ministry in late 1936.

The document lamented the state of physics in Germany, claiming that there were too few up-and-coming physicists and that students were shying away from the subject because of attacks on theoretical physics in the newspapers by National Socialists. Theoretical and experimental physics went hand in hand, it continued, and attacks on either branch should cease. The Memorandum seemed to put a stop to attacks on theoretical physics, in the short term at least. It also illustrated how seriously Geiger and his associates took the threat to their work from the Nazis.

Membership

Geiger was a member of the Saxonian Academy of Sciences, the German Academy of Sciences Leopoldina and the Prussian Academy of Sciences.

Personality

Geiger was a perfectionist, always trying to obtain the most from both his students and his experiments. His enthusiastic and warmhearted nature inspired others to emulate his methods and share his goals. He was a talented lecturer, popular with both his colleagues and the public.

Connections

Geiger married Elisabeth Heffter in 1920. They had three sons.

Father:

Wilhelm Ludwig Geiger

Spouse:

Elisabeth Geiger

Brother:

Rudolf Geiger

colleague:

Ernest Rutherford

colleague:

Ernest Marsden

References

• Dictionary of Scientific Biography