Nuclear fission Frisch-Meitner explanation

In Germany in 1938, Otto Hahn and Fritz Strassmann, skeptical of claims by Enrico Fermi and Irene Johot-Curie that bombardment of uranium by neutrons produced new so-called transuranic elements (elements beyond uranium), repeated these experiments and chemically isolated a radioactive isotope of barium. Unable to interpret these findings, Hahn asked Lise Meitner, a physicist and former colleague, to propose an explanation for his observations. Meitner and her nephew, Otto Frisch, showed that it was possible for the uranium nucleus to be spfit into two smaller nuclei by the neutrons, a process that they termed fission. The discovery of nuclear fission eventually led to the development of nuclear weapons and, after World War II, the advent of nuclear power to generate electricity. Nuclear chemists were involved in the chemical purification of plutonium obtained from uranium targets that had been irradiated in reactors. They also developed chemical separation techniques to isolate radioactive isotopes for industrial and medical uses from the fission products wastes associated with plutonium production for weapons. Today, many of these same chemical separation techniques are being used by nuclear chemists to clean up radioactive wastes resulting from the fifty-year production of nuclear weapons and to treat wastes derived from the production of nuclear power. 

After the discovery of uranium radioactivity by Henri Becquerel in 1896, uranium ores were used primarily as a source of radioactive decay products such as Ra. With the discovery of nuclear fission by Otto Hahn and Fritz Strassman in 1938, uranium became extremely important as a source of nuclear energy. Hahn and Strassman made the experimental discovery Lise Meitner and Otto Frisch provided the theoretical explanation. Enrichment of the spontaneous fissioning isotope U in uranium targets led to the development of the atomic bomb, and subsequently to the production of nuclear-generated electrical power. There are considerable amounts of uranium in nuclear waste throughout the world, see also Actinium Berkelium Einsteinium Fermium Lawrencium Mendelevium Neptunium Nobelium Plutonium Protactinium Rutherfordium Thorium. 

Frisch and Meitner eventually published their theoretical explanation, but the idea was too amazing to keep the lid on for long. Returning to Copenhagen, Frisch told Bohr. In New York at a conference, Bohr told Fermi. Fermi had just left Italy with his Jewish wife, stopping only in Sweden to pick up his Nobel Prize. Accepting a position at Columbia University in New York, he immediately began work on this new idea, now called nuclear fission. He found, as did others, that another product of fission was more neutrons. 

Immediately after the discovery of fission (Hahn and Strassmann 1939), Meitner and Frisch (1939) gave a quantitative explanation of the process using the picture of the LDM. Bohr and Wheeler (1939) developed this picture into their classical theory, which remained the basis for the description of the nuclear fission process for many years to come. 

In 1938, the experimental and theoretical cognition of nuclear fission by O. Hahn and F. Strassmann, and the theoretical explanation by L. Meitner and O. R. Frisch (1944 Nobel Prize to O. Hahn for. .. discovery of the fission of heavy elements...) made our last century the Uranium century. Radiopharmaceutical chemistry, interestingly, has made a significant and exclusively peaceful profit from this nuclear phenomenon, as the fission of uranium today provides an unrenouncable resource of radionuclides applied in nuclear medicine diagnosis and therapy. The uranium fission product l, for example, became a key radionucKde in the 1950s, when R. S. Yalow and S. A. Berson developed the approach of radioimmunoassay for quantitative in vitro analysis of physiological and biochemical processes (1977 Nobel prize to R. S. Yalow for. .. the development of radioimmunoassays...). 

FRISCH, ROBERT OTTO (1904-1979). Austrian-born physicist. Frisch made several fundamental contributions to nuclear physics, especially to the development of nuclear weapons. In 1939, Frisch and his aunt, Lise Meitner, provided the first mathematical explanation for the results of Otto Hahn and Fritz Strassmann and correctly identified that these results confirmed the process of nuclear fission, a term chosen by Frisch himself. 

MEITNER, LISE (1878-1968). Austrian-bom physicist. With her nephew Robert Otto Frisch, Meitner was the first to provide a mathematical explanation for the results of Otto Hahn and Fritz Strass-mann and correctly identify that these results confirmed the process of nuclear fission. Meitner s private communication of their findings to Niels Bohr in December 1938 spurred U.S. development of a nuclear weapon. 

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