American physicist · 1914–2012
Dale R. Corson
Dale Corson co-discovered astatine, the rarest naturally occurring element, in 1940, and later led Cornell University.
How Astatine was found
As a graduate student at Berkeley, Corson worked with Kenneth MacKenzie and Emilio Segrè. They bombarded bismuth with alpha particles in the 60-inch cyclotron and identified element 85 from its radioactivity.
The heaviest halogen, it is so unstable that its longest-lived isotope has a half-life of about eight hours. The team named it astatine, from the Greek astatos, “unstable”, in 1947.
Shared the credit
The discovery is credited jointly to these scientists.
Life and career
Born 1914 · Died 2012
Corson was born in Pittsburg, Kansas. During the war he worked on radar and at Los Alamos. He joined Cornell’s physics department in 1946, became dean of engineering, and was president of the university from 1969 to 1977.
Discovered in the same era
Other elements identified within ten years of 1940.