Nuclear fission Mexico, which was the scientific hub for research on bomb development and design. Other sites, notably the Berkeley Radiation Laboratory and the Metallurgical Laboratory at the University of Chicago, played important contributing roles. Overall scientific direction of the project was managed by the physicist J. Robert Oppenheimer. In July 1945, the first atomic explosive device, dubbed "Trinity", was detonated in the New Mexico desert. It was fueled by plutonium created at Hanford. In August 1945, two more atomic devices – "Little Boy", a uranium-235 bomb, and "Fat Man", a plutonium bomb – were used against the Japanese cities of Hiroshima
Mark 5 nuclear bomb weapons were supplied for delivery by RAF bombers but under US control, under the auspices of Project E. A Mark 5 was used as the primary fission trigger used in Ivy Mike, the first thermonuclear device in history. Mark 5 nuclear bomb The Mark 5 nuclear bomb and W5 nuclear warhead were a common core nuclear weapon design, designed in the early 1950s and which saw service from 1952 to 1963. The Mark 5 design was the first production American nuclear weapon which was significantly smaller than the 60 inch (150 cm) diameter implosion system of the Fat Man nuclear