GLENN THEODORE SEABORG (1912 – 1999)

Starting in 1940, Seaborg and the American physicist Edwin McMillan (1907–1991) used the cyclotron at Berkeley’s Radiation Laboratory to continue the work of Enrico Fermi (1901–1954) in seeking elements beyond uranium. In spring 1940, McMillan’s scientific team discovered the first human-synthesized transuranic element, neptunium (element 93). When McMillan took a leave of absence from Berkeley in November to support critical radar research for the military at the Massachusetts Institute of Technology, Seaborg replaced him as the leader of the research group and continued the search for additional transuranic elements. In December 1940, Seaborg changed human history, when his team synthesized element 94, plutonium. Some additional work quickly indicated that plutonium 239 was a fissile isotope potentially more useful than uranium-235 in nuclear weapons.

During the Manhattan Project, Seaborg strongly advocated the use of plutonium in the first U.S. atomic bomb. He and his scientific team at Berkeley would provide invaluable assistance to Arthur Holly Compton’s bomb design group both at the University of Chicago and, later, at the newly created Los Alamos National Laboratory in New Mexico. In late 1940, there was much to learn about the nuclear, chemical, and metallurgical characteristics of plutonium and little of the material available—only the micrograms produced by the cyclotron at Berkeley. However, Seaborg pressed onward, and Fermi’s successful Chicago Pile One experiment (about a year later, on December 2, 1942) would soon make large quantities of plutonium available for both research and weapons applications.

From 1942 to 1946, Seaborg took a leave of absence from the University of California to head the plutonium work of the Manhattan Project at the University of Chicago’s Metallurgical Laboratory. While providing support for the Manhattan Project, he still managed to pursue his search for other transuranic elements. As part of this quest, in 1944 Seaborg suggested the “actinide concept”— that all the heavy, radioactive elements, starting with actinium (element 89) should be grouped together in the periodic table in a single category, called the actinides. He assumed responsibility for direction of nuclear chemical research at Lawrence’s Radiation Laboratory in Berkeley in 1946. This took place after completion of the Manhattan Project and agreement by officials of the University of California to operate the laboratory under contract with the newly formed U.S. Atomic Energy Commission (USAEC).

As a result of his many years of productive research at the Radiation Laboratory in Berkeley, Seaborg’s name became directly or indirectly associated with the discovery (or first isolation) of the following transuranic elements: element 94 (plutonium, 1940), element 95 (americium, 1944), element 96 (curium, 1944), element 97 (berkelium, 1949), element 98 (californium, 1950), element 99 (einsteinium, 1952), element 100 (fermium, 1952), element 101 (mendelevium, 1955), and element 102 (nobelium, 1958). For his discovery of plutonium, Seaborg shared the 1951 Nobel Prize in chemistry with McMillan, for “their discoveries in the chemistry of the transuranium elements.” From 1954 to 1961, Seaborg served as associate director of the Lawrence Berkeley Radiation Laboratory. In 1958, he was appointed chancellor of the University of California in Berkeley. He remained in that position until President John F. Kennedy appointed him as chairman of the U.S. Atomic Energy Commission in 1961. He served in that capacity, actively promoting nuclear technology, until 1971, when he returned to Berkeley as university professor of chemistry.

In 1991, President George H. W. Bush presented Seaborg with the National Medal of Science. When element 106 was named seaborgium in August 1997, Seaborg became the first living scientist so honored. He died on February 25, 1999, in Lafayette, California, while recuperating from a stroke.