Otto Hahn in the context of "Isotopes of uranium"

Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.

Nuclear fission was discovered by chemists Otto Hahn and Fritz Strassmann and physicists Lise Meitner and Otto Robert Frisch. Hahn and Strassmann proved that a fission reaction had taken place on 19 December 1938, and Meitner and her nephew Frisch explained it theoretically in January 1939. Frisch named the process "fission" by analogy with biological fission of living cells. In their second publication on nuclear fission in February 1939, Hahn and Strassmann predicted the existence and liberation of additional neutrons during the fission process, opening up the possibility of a nuclear chain reaction.

Nazi Germany undertook several research programs relating to nuclear technology, including nuclear weapons and nuclear reactors, before and during World War II. These were variously called Uranverein (Uranium Society) or Uranprojekt (Uranium Project). The first effort started in April 1939, just months after the discovery of nuclear fission in Berlin in December 1938, but ended shortly ahead of the September 1939 German invasion of Poland, for which many German physicists were drafted into the Wehrmacht. A second effort under the administrative purview of the Wehrmacht's Heereswaffenamt began on September 1, 1939, the day of the invasion of Poland. The program eventually expanded into three main efforts: Uranmaschine (nuclear reactor) development, uranium and heavy water production, and uranium isotope separation. Eventually, the German military determined that nuclear fission would not contribute significantly to the war, and in January 1942 the Heereswaffenamt turned the program over to the Reich Research Council (Reichsforschungsrat) while continuing to fund the activity.

The program was split up among nine major institutes where the directors dominated research and set their own objectives. Subsequently, the number of scientists working on applied nuclear fission began to diminish as many researchers applied their talents to more pressing wartime demands. The most influential people in the Uranverein included Kurt Diebner, Abraham Esau, Walther Gerlach, and Erich Schumann. Schumann was one of the most powerful and influential physicists in Germany. Diebner, throughout the life of the nuclear weapon project, had more control over nuclear fission research than did Walther Bothe, Klaus Clusius, Otto Hahn, Paul Harteck, or Werner Heisenberg. Esau was appointed as Reichsmarschall Hermann Göring's plenipotentiary for nuclear physics research in December 1942, and was succeeded by Walther Gerlach after he resigned in December 1943.

Nuclear fission was discovered in December 1938 by chemists Otto Hahn and Fritz Strassmann and physicists Lise Meitner and Otto Robert Frisch. Fission is a nuclear reaction or radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei and often other particles. The fission process often produces gamma rays and releases a very large amount of energy, even by the energetic standards of radioactive decay. Scientists already knew about alpha decay and beta decay, but fission assumed great importance because the discovery that a nuclear chain reaction was possible led to the development of nuclear power and nuclear weapons. Hahn was awarded the 1944 Nobel Prize in Chemistry for the discovery of nuclear fission.

Hahn and Strassmann at the Kaiser Wilhelm Institute for Chemistry in Berlin bombarded uranium with slow neutrons and discovered that barium had been produced. Hahn suggested a bursting of the nucleus, but he was unsure of what the physical basis for the results were. They reported their findings by mail to Meitner in Sweden, who a few months earlier had fled Nazi Germany. Meitner and her nephew Frisch theorised, and then proved, that the uranium nucleus had been split and published their findings in Nature. Meitner calculated that the energy released by each disintegration was approximately 200 megaelectronvolts, and Frisch observed this. By analogy with the division of biological cells, he named the process "fission".

Friedrich Wilhelm Strassmann (German: [fʁɪt͡s ˈʃtʁasˌman] ; 22 February 1902 – 22 April 1980) was a German chemist who, with Otto Hahn in December 1938, identified the element barium as a product of the bombardment of uranium with neutrons. Their observation was the key piece of evidence necessary to identify the previously unknown phenomenon of nuclear fission, as was subsequently recognized and published by Lise Meitner and Robert Frisch.

In their second publication on nuclear fission in February 1939, Strassmann and Hahn predicted the existence and liberation of additional neutrons during the fission process, opening up the possibility of a nuclear chain reaction.

A laboratory notebook (colloq. lab notebook or lab book) is a primary record of research. Researchers use a lab notebook to document their hypotheses, experiments and initial analysis or interpretation of these experiments. The notebook serves as an organizational tool, a memory aid, and can also have a role in protecting any intellectual property that comes from the research.