Hahn worked at first in London where he discovered a new radioactive substance, named radiothorium. He also worked under Ernest Rutherford at Montreal.
On his return to Europe Hahn moved to Berlin, where a thirty years' collaboration with Dr. Lise Meitner began. Following the discovery of artificial radioactivity by M and Mme. Joliot-Curie and the use of neutrons by Fermi for atomic nuclear processes, he bombarded uranium with neutrons. He suggested that bombarded 'uranium' was in fact barium, which led to Lise Meitner's conclusion that the nucleus had been split.
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