The beginning of all that

The discovery of the nuclear fission

Otto Hahn

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Sound recording No. 1

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In 1938/1939, Otto Hahn had discovered in Berlin together with Fritz Straßmann how to split the atomic nucleus of uranium.

Here's a photo of the experimental table of Hahn.

Important contributions were also made from Hahn's colleague Lise Meitner since 1907, who wasn't allowed to witness the success of their work in Berlin.

Lise Meitner

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But it was she who provided the decisive theoretical calculations from her exile which finally prompted Hahn to publish his discovery.

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We also want to remember the young female chemist Ida Noddack from the University of Freiburg, Germany, who expressed in 1934 in the "Zeitschrift für angewandte Chemie" the conjecture of the splitting of the nuclei after the bombardment with neutrons. But she wasn't taken in earnest by Hahn and Fermi.

The danger of a bomb explosive

It was soon recognized that it might be possible to bring about a neutron chain reaction of such splitting with a subsequent release of a vast amount of energy. As early as the summer of 1939, Siegfried Flügge had published a newspaper article openly discussing these possibilities.

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When World War II began, the experiments were declared secret. They were turned over to the Army Weapons Office in Berlin and were looked after by Kurt Diebner, who got the Kaiser Wilhelm Institute for Physics involved in these experiments. Early on, Werner Heisenberg directed their work.

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Werner Heisenberg

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German nuclear research during the War

The total German research work during the War was concentrated on the construction of a nuclear reactor. However, v. Weizsäcker recognized early that a bomb could be realized with the Plutonium, that would be produced in the reactor and that could be extracted easily.

Carl-Friedrich von Weizsäcker

Karl Wirtz

Subsequent experimental work was continued by three research teams. One team worked under Heisenberg at Leipzig, a second team at the Kaiser-Wilhelm-Institut in Berlin (W. Heisenberg, C.F. v. Weizsäcker, Karl Wirtz) and a thrid team was under the military command of Diebner from the Heereswaffenamt in Berlin-Gattow.

The decision

At a meeting at the Heereswaffenamt in February 1942, Heisenberg replied to the question, if there could be built a war-decisive weapon within nine months, with a clearcut "No". Thereupon, the Nazis lost theit interest in the project. The responsibility for the entire enterprise was withdrawn from the Heereswaffenamt and transferred to the Reichsforschungsrat (National Research Council). The control of this project was taken over by Walter Gerlach in 1944.

Danger of life

By 1943, the air raids on Berlin were becoming so intense that work became impossible there.An area was sought which was still relatively safe from air attacks. South-West-Germany had largely been spared from such attacks so far. It was also foreseen that in the event of occupation, hardly any Sowjet troops would penetrate into this area. The scientists by no means wanted to fall prey to the Sowjet Union as an occupational power.

Michael.Thorwart@physik.uni-augsburg.de(Aug-11-1997)