Detection of Neutrons Liberated from Beryllium by Gamma Rays: a New Technique for Inducing Radioactivity

SZILARD, LEO; CHALMERS, T. A.

doi:10.1038/134494b0

Letter
Published: 01 September 1934

Detection of Neutrons Liberated from Beryllium by Gamma Rays: a New Technique for Inducing Radioactivity

LEO SZILARD¹ &
T. A. CHALMERS¹

Nature volume 134, pages 494–495 (1934)Cite this article

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We have observed that a radiation emitted from beryllium under the influence of radium gamma rays excites induced radioactivity in iodine, and we conclude that neutrons are liberated from beryllium by gamma rays.

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References

NATURE, 134, 237, Aug. 18, 1934.
NATURE, 134, 462, Sept. 22, 1934.

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Authors and Affiliations

Physics Department, Medical College, St. Bartholomew’s Hospital, London, E.C.1. Sept. 17. https://www.nature.com/nature
LEO SZILARD & T. A. CHALMERS

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LEO SZILARD
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T. A. CHALMERS
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SZILARD, L., CHALMERS, T. Detection of Neutrons Liberated from Beryllium by Gamma Rays: a New Technique for Inducing Radioactivity. Nature 134, 494–495 (1934). https://doi.org/10.1038/134494b0

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Published: 01 September 1934
Issue Date: 29 September 1934
DOI: https://doi.org/10.1038/134494b0

Editorial Summary

Neutron-induced radioactivity

In September 1934, Leo Szilard and T. H. Chalmers let gamma rays fall onto a beryllium target, noting that emissions from the target induced radioactivity in iodine. "We conclude," they wrote, "that neutrons are liberated from beryllium by gamma rays." Two months later, A. Brasch and colleagues, including Szilard and Chalmers, reported a similar effect using X-rays rather than gamma rays. More ominously, the existence of neutron-induced radioactivity also suggested the possibility of neutron chain-reactions - using the neutrons emitted by radioactive elements to induce radioactivity, and liberate further neutrons, from other nuclei. The first demonstration came four years later, following the discovery of nuclear fission in uranium.

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