On the Twentieth Anniversary of the Discovery of Artificial Radioactivity

From the Editors

This year marks twenty years since the discovery (in 1934) by Frédéric and Irène Joliot-Curie of the phenomenon of artificial radioactivity. This discovery belongs among the most important events in the history of science. Like the discovery of radium, made 55 years ago (1898) by Marie and Pierre Curie, it marked the beginning of a new stage in the development of nuclear physics; moreover, it created new, unforeseen possibilities for the application of radioactivity in the most diverse fields of science and technology. Below, for the first time in Russian, is reproduced the text of the original paper by F. and I. Joliot-Curie in which they reported their discovery.

A New Type of Radioactivity*)

Irène Curie and F. Joliot

We have recently shown, by means of the Wilson chamber method[^1], that certain light elements (beryllium, boron, aluminum) emit positive electrons when bombarded by the $\alpha$-rays of polonium. According to our interpretation, the emission of positive electrons by beryllium should be attributed to the internal materialization of $\gamma$-radiation, whereas the positive electrons emitted by B and Al are electrons arising in a nuclear reaction and accompanying the emission of neutrons.

In attempting to clarify the mechanism of these phenomena, we have found the following.

) Comptes Rendus 198*, 254—256 (1934).