Abstract
THE Nobel Prize for Physics for 1938 has been awarded to Prof. E. Fermi, professor of theoretical physics in the University of Rome, and his work in connexion with artificial radioactivity induced by neutrons is specially mentioned in the award. Bombardment of the nucleus with neutrons is peculiarly effective in producing nuclear reactions because the neutron does not experience the strong electrostatic forces which oppose the approach of a proton or a-particle. Fermi in 1934 showed that most nuclei, even the heaviest which are most resistant to charged particles, are disrupted by neutrons with the formation of new radioactive nuclei. In the same year, he discovered that the effectiveness of neutron bombardment is greatly increased in the presence of masses of water or paraffin, and concluded that the neutrons are slowed down by collisions with hydrogen nuclei in these substances, and that the slow neutrons have a high probability of entering and disrupting nuclei. Prof. Fermi has, however, made other outstanding contributions to atomic physics. In 1926 he applied Pauli's exclusion principle to deduce a new kind of statistics for electrons (Fermi-Dirac statistics). He applied this to the assemblage of electrons in an atom (Thomson-Fermi atom model), and it has become the basis of the modern theory of electrons in metals. In 1934 he devised a theory of β-decay, starting from the view that a β-particle is emitted when a neutron in the nucleus turns into a proton. *The distribution of energies in a continuous spectrum requires that a neutral particle (neutrino) be emitted with the β-ray. This theory has formed the starting point for many more recent discussions. Fermi has also published work on spectroscopy, on quantum electrodynamics, and, with Rossi, on the deflection of cosmic rays in the earth's magnetic field.
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Prof. Enrico Fermi. Nature 142, 906–907 (1938). https://doi.org/10.1038/142906c0
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DOI: https://doi.org/10.1038/142906c0