Vienna Radium Institute

Just a year later three radiochemists from Vienna— S. Meyer, G. Hess, and F. Paneth—studied actinium-227, an isotope belonging to the family of uranium-235. They repeated their experiments and at last their sensitive instruments detected alpha particles of unknown origin. Alpha particles emitted by various isotopes have specific mean paths in air (of the order of a few centimetres). The mean path of the alpha particles in the experiments of the Austrian scientists was 3.5 cm. No known alpha-active isotope had such mean path of alpha particles. The scientists from the Vienna Radium Institute concluded that these particles were the product of alpha decay of the typically beta-active actinium-227. A product of this decay had to be an isotope of element 87. 

But in the interval between the syntheses of the isotopes At and At a remarkable event occurred. The scientists from the Vienna Radium Institute B. Karlik and T. Bernert managed to find natural astatine. This was an extremely skillful study straining to the utmost the capacity of radiometry. The work was crowned with success and element 85 was born for the second time. As in the cases of technetium and promethium, we can name two dates in the history of astatine, namely, the year of its synthesis (1940) and the year of its discovery in nature (1943). 

Laboratory at the University of Munich. At the Radium Institute in Vienna he made the first accurate determination of the atomic weight of radium. His work on radioactive elements strikingly confirmed the hypothesis of atomic disintegration proposed by Rutherford and Soddy. 

For information on Karlik, see Rentetzi, M. (2004). Gender, politics, and radioactivity research in interwar Vienna The case of the Institute for Radium Research. Isis 95 359—393. 

Part of the experiments were carried out in the Institut fur Radium-forschung und Kernphysik, Vienna, Austria. 

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