Design and fabrication of the first atomic weapons became the responsibility of the newly established Los Alamos Laboratory, in northern New Mexico. Headed by J. Robert Oppenheimer, the laboratory assembled an array of scientists from universities across the United States. Designing the first atomic weapons was not an easy task and required precise calculations and months of experimentation to obtain the optimum specifications of size and shape.
Two bomb models were developed by mid-1944. The gun-type bomb, named Little Boy, used enriched uranium from Oak Ridge. Fat Man, the implosion-type weapon, used plutonium produced at Hanford. Field tests with the uranium prototype eased doubts about the design, so that a full-scale test prior to combat use was deemed unnecessary. The plutonium device was more problematic. Uncertain that it would work, officials successfully tested the implosion method at the Trinity site in southern New Mexico on July 16, 1945. The Trinity Test ushered in the nuclear age with the world's first human-caused nuclear explosion. Learn more about the design and development of these atomic weapons in the articles below.
The Gadget was the first atomic bomb ever detonated to test the complex implosion design using plutonium. On July 16, 1945 at 5:29 AM Mountain War Time, the Gadget successfully detonated in the remote New Mexico desert, officially ushering in the atomic age.
On April 20, 1943, the University of California signed a contract with the United States Army Corps of Engineers to operate a secret laboratory hidden away in the mountains of northern New Mexico. This laboratory soon became home to some of the most revolutionary science in US history. Led by scientist J. Robert Oppenheimer, the staff at this secret Manhattan Project location called Los Alamos was responsible for the development and testing of nuclear weapons.
Test leader Edward Creutz joined the Manhattan Project in 1942 as a physicist at the University of Chicago Metallurgical Lab. Working under Eugene Wigner, Creutz helped design water-cooled production reactors, which became the basis for the nuclear reactors at the Hanford Site. In 1944, Creutz moved to Los Alamos to develop explosive lenses for Fat Man, the first implosion-type weapon. Find out more about tour reservations and schedules on the Bradbury Museum website.
By studying magnetic field disruptions at the Battleship Bunker (TA-18-2), scientists learned more about implosion. This building is on Los Alamos National Laboratory property. You can only access it through guided tours offered on specific dates. Find out more about tour reservations and schedules on the Bradbury Museum website.
This concrete bowl remains an example of the wartime laboratory’s practice of simultaneously testing different solutions to solve complex problems. In the decades since the bowl’s construction, weeds and trees have moved in and the local wildlife have discovered it as a reliable watering hole on the arid Pajarito Plateau. This site is on Los Alamos National Laboratory property and cannot be accessed by members of the public.
K-Site takes its name from Donald Kerst, the physicist who headed the studies here. He had developed the betatron while working as an instructor at the University of Illinois. His work there, and his reputation as a capable physicist and engineer, prompted Dr. J. Robert Oppenheimer to bring him to Los Alamos. This site is on Los Alamos National Laboratory property and cannot be accessed by members of the public.
As theories and designs for the gun-type weapon developed, scientists needed a firing range to run tests in the field. A nearby ranch, known as Anchor Ranch, served this purpose after the War Department purchased the land. The firing range gave researchers a chance to study projectile movement, the effects of impact, interior ballistics, and more. This site is on Los Alamos National Laboratory property and cannot be accessed by members of the public.
Headed by Henry Linschitz, the Terminal Observation Group (X-1B) used L-Site as a firing site. After setting off high-explosives, the group would study the physical remains of the shots. The firing pit, constructed of heavy timber, has steel plating around the sides and a steel lid to protect from explosive blasts. This site is on Los Alamos National Laboratory property and cannot be accessed by members of the public.
From the outside, Pond Cabin looks like any typical Southwestern ranch building. Its rustic appearance belies the role it played in groundbreaking plutonium research. During the Manhattan Project, Emilio Segrè used the cabin as an office for his plutonium research team. This building is on Los Alamos National Laboratory property. You can only access it through guided tours offered on specific dates.
At Q-Site, innovative new photography techniques helped scientists understand small-scale implosion. Using a rotating prism camera, X-ray and photographic techniques gathered data about cylinder implosions. This site is on Los Alamos National Laboratory property and cannot be accessed by members of the public.
National Park Service, Manhattan Project National Historical Park
c/o NPS Intermountain Regional Office
One Denver Federal Center, Building 50
Denver,
CO
80225-0287
Phone:
Hanford: 509.376.1647
Los Alamos: 505.661.6277
Oak Ridge: 865.482.1942
