The element was first synthesized in 1940 by Dale R. Corson, K. R. MacKenzie, and Emilio Segrè after several scientists in vain searched for it in radioactive minerals.
Karlik also attended a fellowship from the International Federation of University Women, which required her to travel while working for the Radium Institute.
[2] Simultaneously, Karlik joined a group on seawater research headed by the Swedish physicist Hans Pettersson.
Mixing knowledge of oceanography and radioactivity, Karlik helped to bring up concerns about the biological issue of uranium contamination of seawater.
[1] During the Second World War, she made her most important discovery, that the element with the atomic number 85, Astatine, was a product of natural decay.