Iwanenko, D.D.; The Neutron Hypothesis
Nature 129 (1932) 798;
Dr. J. Chadwick's explanation of the mysterious beryllium radiation is very attractive to theoretical physicists. Is it not possible to admit that neutrons play also an important role in the building of nuclei, the nuclei electrons being all packed in -particles or neutrons? The lack of a theory of nuclei makes, of course, this assumption rather uncertain, but perhaps it sounds not so improbable if we remember that the nuclei electrons profoundly
change their properties when entering into the nuclei, and lose, so to say, their individuality, for example, their spin and magnetic moment. The chief point of interest is how far the neutrons can be considered as elementary particles (something like protons and electrons). It is easy to calculate the number of -particles, protons, and neutrons for a given nucleus, and form in this way an idea about the momentum of nucleus (assuming for the neutron
a moment 1/ 2). It is curious that berillium nuclei do not possess free protons but only -particles and neutrons.
Suggestion that the neutron is a constituent of the atomic nucleus.