Abstract
A CONSIDERABLE number of tissues have been exposed to very high energy Be-D neutrons (˜ 12 Mev.) with the help of cyclotrons, in the United States. The published values of the ratio γ/N of the gamma-ray to the neutron doses for a given biological effect range from 2 to 8. These ratios should be comparable among themselves, but since the neutron doses were measured in arbitrary units they cannot, without further experiment, be regarded as indicating the ratio of the absorbed neutron and gamma-ray energy. Two investigations have been reported in which an attempt has been made to measure this quantity. Zimmer1, using Li-D neutrons, found the ratio of gamma-ray to neutron energy necessary to produce the same increase in mutation rate in Drosophila sperm to be γ/N = 0·7, whereas for the lethal effect on the bean root we2 have found γ/N = 11. Comparable procedures were adopted for the estimation of the neutron energy absorbed in the tissue in the two cases, and these were roughly checked by the exchange of ionization chambers3.
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Zimmer, Str. Th., 63, 517; 63, 523 (1933).
Gray, Read and Mottram, NATURE, 144, 479 (1939)
Gray and Read, Nature, 144, 439 (1939).
Ladenburg and Roberts, Phys. Rev., 59, 1190 (1930). Kikuchi and Aoki, Phys. Rev., 55, 103 (1939).
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GRAY, L., READ, J. Quantitative Comparison of the Biological Effects of Neutrons and other Ionizing Radiations. Nature 144, 509 (1939). https://doi.org/10.1038/144509a0
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DOI: https://doi.org/10.1038/144509a0
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