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On the Earlier and More Recent History of the Neutrino

  • Wolfgang Pauli
Chapter

Abstract

The continuous energy spectrum of beta rays, discovered by J. Chadwick in 1914,’ immediately raised difficult problems of theoretical interpretation. Was it to be ascribed directly to the primary electrons emitted by the radioactive nucleus, or to secondary processes? The first view, which turned out to be the correct one, was advocated by C. D. Ellis,2 the second by L. Meitner.3 The latter appealed to the fact, known from alpha and gamma rays, that nuclei possess discrete energy levels. She focused the discussion on the discrete energies of the electrons which are likewise observed in many beta-radioactive nuclei. Ellis was able to interpret these as electrons ejected from the outer shells by monochromatic nuclear gamma rays by internal conversion, and to relate them to the observed X-ray lines. According to L. Meitner’s theory however, at least one of the electrons of discrete energy was a genuine primary electron from the nucleus, which could then likewise eject other secondary electrons of lower energies from the outer shells.4 This postulated primary electron of discrete energy could however never be detected. Moreover there are beta-radioactive nuclei, such as RaE, which do not emit gamma rays and in which moreover the electrons of discrete energy are completely absent.

Keywords

Physical Review Recent History Lepton Charge Beta Decay Rest Mass 
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References

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    L. Meitner, Zeitschrift für Physik 11, 35 (1922). electrons of lower energies from the outer shells. 4This postulated primary electron of discrete energy could however never be detected. Moreover there are beta-radioactive nuclei, such as RaE, which do not emit gamma rays and in which moreover the electrons of discrete energy are completely absent. In the controversy which arose between Ellis and L. Meitner, Ellis 5 in 1922 summarised his position as follows: Frl. Meitner’s theory is a very interesting attempt to give a simple explanation of βdecay. The experimental facts do not however fit into the framework of this theory, and it looks very much as if the simple analogy between a- and β-decay cannot be maintained. β-decay is a much more complicated process and the general indications I have given about it appear to me at the moment to involve a minimum of constraint.”CrossRefADSGoogle Scholar
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    In a later paper (Zeitschriftfür Physik 34, 807 (1925)) L. Meitner showed experimentally that, contrary to an earlier view of Ellis, the y-rays are emitted by the nucleus produced after the emission of the a- or β-particles.Google Scholar
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© Springer-Verlag Berlin Heidelberg 1994

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  • Wolfgang Pauli

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