January 18, 1945 - Death of Sonia Cotelle, who determined the half-life of thorium-230 and established the atomic number of polonium

With a degree in general, biological and applied chemistry from the Sorbonne University (France), she specialised in radioactive sources.

In 1919, she began her work as a researcher, joining the team of scientist Marie Curie at the Institut du Radium (now the Curie Museum) in Paris (France).

Between 1926 and 1927, she researched polonium and actinium in collaboration with Marie Curie. She also determined the half-life or average lifetime of ionium, the name by which thorium-230 was known at the time.

Between 1927 and 1936, Cotelle lived in Czechoslovakia and determined the atomic number of polonium using X-ray spectroscopy.

If you would like to learn more about this scientist, click on the following link: Sonia Cotelle