Abstract
CONTRARY to expectations, γ -rays of 17 million volts energy eject neutrons from the nuclei of some of the heavier elements only. Prof. Niels Bohr suggests that this selective behaviour is conditioned by “certain special vibratory motions with singular radiation properties”and these, together with other possible modes of vibration, lead to an energy distribution analogous to that of the heat motions in a solid body at a low temperature. The radiative properties of the nucleus in this state will resemble that of a black body with a temperature of several million volts. Based on this analogy Prof. Bohr gives a formula of selective absorption, relating the cross-section for nuclear photo-effects with the frequency of the incident γ -rays and the probabilities for the re-emission of a quantum.
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Points from Foregoing Letters. Nature 141, 334 (1938). https://doi.org/10.1038/141334a0
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DOI: https://doi.org/10.1038/141334a0