Obituary: Norris Bradbury

Norris Bradbury followed J. Robert Oppenheimer in 1956 as director of the Los Alamos Scientific Laboratory in New Mexico and held that position longer than any other director, until 1970.

More than any other single individual, Bradbury was responsible for the success of Los Alamos in developing mass-produced nuclear weapons to replace the crudely engineered and highly inefficient devices used to end the Second World War. As head of the "gadget engineers" who conducted the world's first nuclear test at Trinity Site in the Jornado del Muerto area, north of Alamogordo, New Mexico, Bradbury was keenly aware of the shortcomings of those devices.

In a laboratory denuded of its most prominent talents at the end of the war, he led the team that developed the atomic weapons that were the mainstay of the nuclear arsenal for the next two decades, and, despite the recalcitrance and, eventually, the resignation of the physicist Edward Teller, he succeeded in developing the world's first thermonuclear device by 1952 in response to the arms race launched by the Soviet Union in September 1949.

Bradbury's accomplishments went far beyond successful nuclear weapons, however. He insisted upon the laboratory's freedom to participate in fundamental scientific research in nuclear physics, chemistry and materials science, biology and medicine, and other fields only remotely related to nuclear weapons.

Many engineers and scientists were thus attracted to the remote laboratory, which was completely rebuilt under Bradbury's direction after the war. Among other scientific tools added at that time were the world's largest Van de Graaff electrostatic generator, a series of advanced research reactors, the Maniac computer, and the Los Alamos Meson Physics Facility, which is still a centre of basic science research at the Laboratory. Many important scientific accomplishments resulted. Frederick Reines and Clyde Cowan first detected the neutrino with detectors built at Los Alamos, an accomplishment that was recognised by a Nobel Prize in Physics to Reines in 1996.

Bradbury was born in Santa Barbara, California in 1909. After receiving his first degree at Pomona College, Claremont, in 1929, where he studied under Roland Tileston, he studied gaseous ion mobility under Leonard Loeb at the University of California, Berkeley, where he received his PhD in physics and mathematics in 1933. After two years at the Massachusetts Institute of Technology (MIT) on National Research Fellowship, he was appointed to the Stanford University physics faculty, where he rose to become full professor in 1942.

At the onset of the Second World War, Bradbury accepted active service in the Navy, and travelled to the Naval Proving Ground at Dahlgren, Virginia, where he worked on projectile ballistics. In 1945, he joined Los Alamos to assemble the implosion device.

At Los Alamos, Bradbury rose rapidly through the ranks and, after overseeing the gadget's test at Trinity and its deployment, he was chosen to head the laboratory after the departure of J. Robert Oppenheimer in the autumn of 1956.

With Oppenheimer went most of the people who had been responsible for the design, development, and test of the implosion device. Under Bradbury's leadership, the outflow of manpower was ended, and, with the failure of Allied proposals for international control of nuclear weapons, the laboratory began a new career of providing a nuclear arsenal for the Cold War. In addition to perfecting fission weapons, Bradbury also led the effort that resulted in the world's first thermonuclear device in 1952. Edward Teller, who had worked on the plans for such a device at Los Alamos as early as 1944, had resigned from the laboratory in the preceding year because of his political differences with Bradbury, and founded a rival weapons laboratory at Livermore.

Bradbury was an advocate of the Limited Test Ban Treaty of 1963, and, as early as 1955, argued that the nuclear arms race must be halted. He was elected to the National Academy of Sciences in the United States in 1952 and was decorated with the Legion of Merit of the United States Navy in 1945.

Bradbury was respected and loved by the scientists and engineers at the laboratory, and was honoured by the naming of the Bradbury Science Museum after him in 1984. He told me he felt that it was inappropriate to memorialise the living in this fashion, but no more appropriate monument to his legacy could have been imagined.

Robert W. Seidel

Norris Edwin Bradbury, physicist: born Santa Barbara, California 30 May 1909; Director, Los Alamos Scientific Laboratory 1956-70; married 1933 Lois Platt (three sons); died Los Alamos, New Mexico 20 August 1997.