Dr. J. Carson Mark joined the Manhattan Project in May 1945 with a delegation of British scientists. He worked in the Los Alamos Scientific Laboratory, and in 1947, went on to head its Theoretical Division. Mark stayed on after the end of the Second World War as part of the project aimed at developing the hydrogen bomb. In this interview, Mark addresses the challenges involved in making a hydrogen bomb, including the design process and the conflicts between other scientists in the laboratory. He also discusses the Soviet hydrogen bomb, and the problems their project faced, despite Soviet espionage in the United States.
George Cowan was a physical chemist who joined the Manhattan Project in 1942. In this interview, Cowan discusses the Soviet atomic program and their effort to build a nuclear bomb. In 1949, he helped convince U.S. government officials that the radiochemistry of air samples taken from the atmosphere proved that the Soviets had detonated their own atomic bomb, rather than what many assumed was just a peaceful nuclear reactor problem. Cowan also discusses Operation Crossroads, where he helped take air samples during atomic tests at Eniwetok Atoll in 1946.