Pioneering Work on Nuclear Fission

Otto Hahn: In particular, Fermi concluded that by irradiationg uranium with neutrons, he had formed trans-uranic elements -- that is, elements of higher atomic number than uranium.

Miss Lise Meitner, Fritz Strassmann, and I decided to repeat and extend his very interesting experiments. We felt well qualified to do so. The physicist Lise Meitner and I had worked together on problems of radioactivity for over thirty years. Fritz Strassmann, my friend, possessed unique abilities in analytical inorganic chemistry, and I had been in the field of radioactive chemistry from the early days of the beginning of the century, many years ago, with fairly good results.

During the four years, the joint work from 1934 to 1938, we published a number of papers -- Meitner, Hahn, Strassmann -- believing that we had isolated isotopes of the elements 93 to 96, and our results were generally accepted. But toward the end of 1938, when Lise Meitner had been compelled to leave Germany and had emmigrated to Sweden, Dr. Strassmann and myself we came to the startling conclusion that the impact of a neutron on a uranium nucleus caused it to undergo fission into two medium-sized nuclei, a process which had not been thought previously to be possible. These results, which we published with some hesitation, were confirmed very quickly by physicists in Denmark and the United States, and other countries. The rest is well-known.