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Artificial Radioactivity of Dysprosium and other Rare Earth Elements


IN their pioneer work on artificial radioactivity through neutron bombardment, Fermi and his collaborators announced the discovery of the activity of some of the rare earth elements, namely, of lanthanum, praseodymium, neodymium, samarium and gadolinium. Recently, Sugden1 found that terbium shows an appreciable, and europium a very strong, radioactivity after bombardment with neutrons. We find that dysprosium shows an unusually strong activity due to 66Dy165 under the action of slow neutrons; so far as we can ascertain, it is the strongest activity found hitherto. So little as 1/100 mgm. of dysprosium gives an easily detectable radioactivity after bombardment with neutrons from a source containing a few hundred millicuries of radium emanation.


  1. S. Sugden, NATURE, 135, 469; 1935.

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  2. E. Fermi, E. Amaldi, O. D'Agostino, F. Rasetti and E. Segrè, Proc. Roy. Soc., A, 146, 483; 1934.

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HEVESY, G., LEVI, H. Artificial Radioactivity of Dysprosium and other Rare Earth Elements. Nature 136, 103 (1935).

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