Neutron Release in the Nuclear Explosion of Uranium

Recent experiments have revealed a new type of nuclear reaction: neutron bombardment of uranium and thorium leads to a nuclear explosion, which splits into charged particles of lesser mass, releasing a large amount of energy in the process. Assuming the nucleus splits into only two fragments, the nuclear mass and charge of uranium must be distributed between two lighter nuclei, resulting in the lighter nucleus containing a significantly larger number of neutrons compared to the heavier stable isotopes with the same nuclear charge. (For example, dividing into 98Rb and 141Cs means there is a surplus of 11 neutrons in the first, and 8 neutrons in the second of these two nuclei.) There appear to be two possibilities for disposing of this neutron surplus. By emitting an alpha particle, a neutron converts to a proton, reducing the surplus of neutrons by two units. In the aforementioned example, five and four consecutive alpha decays would be needed to restore the neutron-to-proton stability ratio. Indeed, the explosion products have been observed to be active in alpha emissions, and several periods have been registered, thereby disposing of at least part of the neutron surplus in this manner. Another possible process is the direct release of neutrons, either as part of the explosion itself, or as “vaporization” from the resulting nuclei that would form in an excited state.

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About the book

Authors: H. VON HALBAN JUN., F. JOLIOT, L. KOWARSKI

About the authors: Laboratoire de Chimie Nucléaire, Collège de France, Paris

This article was published in Nature on March 18, 1939.

Journal number: volume 143, pages 470–471 (1939)

Digital Object Identifier for the article: https://doi.org/10.1038/143470a0

Source: https://www.nature.com/articles/143470a0