1907-1991

American physicist who co-discovered the first transuranium element, neptunium. McMillan was director of the radiation facility at the University of California, Berkeley. His research, along with colleague Glenn Theodore Seaborg's, led to the discovery of plutonium. He and Seaborg share the 1951 Nobel Prize in Chemistry for their work in transuranium elements. Transuranium elements are elements with an atomic number greater than 92.