American chemist · 1916–1957
Joseph W. Kennedy
Joseph Kennedy co-discovered plutonium in 1941 and then, while still in his twenties, led the chemistry and metallurgy of the Los Alamos weapons laboratory.
How Plutonium was found
Kennedy was an instructor at Berkeley who had built some of the best radiation counters there. He worked with Seaborg and his student Arthur Wahl to identify element 94, and soon afterwards helped show that plutonium-239 splits under slow neutrons.
Shared the credit
The discovery is credited jointly to these scientists.
Life and career
Born 1916 · Died 1957
Kennedy was born in Nacogdoches, Texas. At Los Alamos he directed the division that purified plutonium and shaped it into bomb cores.
After the war he became head of the chemistry department at Washington University in St. Louis. He died of cancer at 40.
Discovered in the same era
Other elements identified within ten years of 1940.