Abstract
Models for radioactive disintegration Between 1911 and 1928 only a few authors made a contribution to models for radioactive disintegration. Most authors thought of radioactive disintegration as a consequence of the mutual repulsive or attractive forces between the particles inside a decaying atom, whenever these particles reached an instable configuration.
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In the other cases use was made of the cumulative effect of small irregularities in the paths of the particles in the nucleus, or of an analogy of lightning to make the process of radioactive disintegration intelligible. None of the models for radioactive disintegration attracted much attention. The most influential model was the one proposed by F.A. Lindemann in 1914. Lindemann's model was based on an empirical relationship between the range of aparticles and the lifetime of a decaying atom, which was found by H. Geiger and J.M. Nutall in 1911, Like the Geiger-Nutall-relation. this model was confined to substances emitting n-rays. Lindemann's model and the treatises based on it were more quantitative in character than the other models. Lindemann assumed that the nucleus of a radioactive element became instable when ,V independent particles passed through some unknown critical position within a short time r. He further assumed that the particles in the nucleus rotated or oscillated with the mean energy E—hv, the energy of the a-particle emitted. Using the Geiger-Nutall-relation and a few additional assumptions Lindemann found N to be equal to 80. This seemed to show, that nearly all the positive particles inside the nucleus had to conspire to bring about the disintegration of the atom. An interesting development could be seen in the use that was made of the Geiger-Nutallrelation by the authors who contributed to Lindemann's model. Lindemann just used the overall relationship. Meyer and W'olff stressed the differences between the three radioactive series. In Kirsch' treatises, however, the Geiger-Nutall-relation had partly lost its empirical content.The two most detailed models for the process of radioactive disintegration were proposed bij Wolff and Kirsch. Though both models were based on Lindemann's model, the differences were notable. Wolff assumed that in all isotopes within one series a similar change took place inside the nucleus, immediately before the disintegration. When an atom disintegrated, the outmost a-particle was emitted. In Kirsch' model the disintegration of an atom came about in a similar manner only for a part of the series. In this model it was always the innermost a-particle that was emitted.
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