Project Y

The Los Alamos Laboratory, also known as Project Y, was a secret scientific laboratory established by the Manhattan Project and overseen by the University of California during World War II. It worked closely with the United States Army and aimed to design and build the first atomic bombs. The laboratory was led by scientist J. Robert Oppenheimer from 1943 until 1945, and later by Norris Bradbury. To keep discussions secure, it was built on the isolated Pajarito Plateau in northern New Mexico, using buildings from an old school called the Los Alamos Ranch School.

Scientists at Project Y first tried to create a bomb called Thin Man using a material named plutonium. However, they discovered that plutonium would explode too early, so they switched to a different design called Fat Man, using a method known as implosion. They also developed another bomb named Little Boy using uranium. The laboratory made important advances, such as purifying uranium and plutonium, and even built an early reactor called the Water Boiler.

The work at Project Y led to the Trinity nuclear test in July 1945, the first ever test of an atomic bomb. Later, scientists from the laboratory helped with the atomic bombings of Hiroshima and Nagasaki in Japan. After the war, the laboratory continued its work, supporting nuclear tests like Operation Crossroads at Bikini Atoll and eventually became known as the Los Alamos Scientific Laboratory.

Origins

Nuclear fission and atomic bombs

The discovery of the neutron by James Chadwick in 1932 and the discovery of nuclear fission by Otto Hahn and Fritz Strassmann in 1938 showed that it might be possible to create a controlled nuclear chain reaction using uranium. This worried scientists, especially because of the danger that Nazi Germany might develop such weapons first. This concern led to the Einstein–Szilard letter to President Franklin D. Roosevelt, which started research in the United States in late 1939.

British scientists, including Otto Frisch and Rudolf Peierls, studied how to make atomic bombs and found that a small amount of uranium-235 could release huge amounts of energy. They shared their findings with American scientists, helping to speed up the research. By July 1941, a British committee called the MAUD Committee reported that building an atomic bomb was possible, perhaps even by 1943. This report inspired more urgency in the United States.

Bomb design concepts

Scientists met to discuss how to build an atomic bomb. They knew they needed either uranium-235 or plutonium, a new element recently discovered. They considered different ways to arrange the material to create a powerful explosion. One idea was to shoot a piece of material into a larger piece to start the reaction. Another idea, called “implosion,” would squeeze the material quickly to make it explode.

Some scientists, like Edward Teller, also talked about a much more powerful bomb called a “hydrogen bomb,” which would use a fission bomb to start a nuclear fusion reaction. However, they decided to focus first on building fission bombs.

Bomb laboratory concept

J. Robert Oppenheimer suggested creating a special laboratory where scientists could work together in one place. This idea was supported by Brigadier General Leslie R. Groves Jr., who became the director of the Manhattan Project. In October 1942, Groves approved the plan to create this new laboratory, which would later be known as Project Y. Despite some concerns about Oppenheimer’s lack of experience and security issues, Groves decided to appoint him as the leader of this important new scientific effort.

Site selection

See also: Acquiring land for Los Alamos Laboratory

When planning Project Y, leaders considered many places for the laboratory. They wanted a spot that was far away for safety. They looked at areas near Los Angeles and Reno, Nevada, but these did not work well. Finally, they chose a place near Albuquerque, New Mexico, partly because the scientist in charge, J. Robert Oppenheimer, owned a ranch there and liked the area.

The team visited several sites, but they picked one close to the Los Alamos Ranch School because it was beautiful and had nice views. They worried about things like roads and water, but overall it seemed like a good choice. The government bought the land, which included parts of schools, farms, and natural areas, to make sure everyone could work safely there.

Construction

The Los Alamos Ranch School had 54 buildings, including houses and a sawmill, which were used as the base for the new laboratory. Construction began in December 1942 and was supervised by the Albuquerque Engineer District until March 1944, when the Manhattan Engineer District took over. The M. M. Sundt Company started the initial construction work.

By the end of 1943, about 3,500 people lived there, growing to 10,000 by the end of 1946. Most were scientists and their families. Housing included old school cottages known as “Bathtub Row,” apartments, and prefabricated homes. A school opened in 1943 for children living in Los Alamos.

The town grew quickly, and services like water and electricity couldn’t keep up. Sometimes lights had to be turned off during the day. Los Alamos was called “Site Y” because its name was secret, and residents couldn’t vote in elections until 1949.

Organization

The Los Alamos Laboratory, also known as Project Y, was a secret scientific laboratory established during World War II as part of the Manhattan Project. Colonel John M. Harman was the first post commander, followed by several others including Lieutenant Colonel C. Whitney Ashbridge and Colonel Herb C. Gee. The laboratory was overseen by the University of California and operated in partnership with the United States Army.

J. Robert Oppenheimer served as the first director from 1943 to 1945, focusing on the technical and scientific aspects of building the first atomic bombs. He assembled a team of scientists from various universities, including the University of California, University of Minnesota, and Stanford University. The laboratory included military units such as the MP Detachment and the Special Engineer Detachment, as well as civilian staff, with women playing important roles in administration, science, and technical work. The British Mission, led by James Chadwick, also contributed to the laboratory’s efforts before leaving after the Atomic Energy Act of 1946.

Gun-type weapon design

Research

In 1943, scientists at Los Alamos worked on a design for a gun-type fission weapon called Thin Man, using plutonium. The names for the atomic bomb designs—Fat Man, Thin Man, and Little Boy—were chosen based on their shapes and inspired by characters from detective novels and movies.

Researchers tried to estimate how much material was needed for the bomb to work. They faced challenges because they had very little plutonium to test with. Experiments were conducted to measure how many neutrons were released when plutonium and uranium split, which is key to making a bomb work.

Development

In June 1943, Morgan Parsons was appointed to lead the Ordnance and Engineering Division. The team designed a special gun to fire the bomb. Because this gun would only be used once, it could be made lighter and simpler than regular guns.

The scientists tested different materials and systems to make sure everything worked correctly. They also tested radar devices to determine the best way to trigger the bomb when it was dropped from an aircraft. These tests helped prepare the design for use in actual missions.

Plutonium

Scientists were concerned that impurities in plutonium might cause it to react too early in a bomb. They tested small amounts of plutonium and found that its properties were different from what they expected. For example, its density and melting point were lower than they thought.

When they tested larger samples, they discovered that a specific type of plutonium, called plutonium-240, could cause the bomb to react too quickly. This meant that the original design for the bomb would not work, and they had to find a new way to build it.

Implosion-type weapon design

Scientists at the Los Alamos Laboratory worked on a different way to build an atomic bomb called "implosion." Instead of shooting one piece of material into another, they used explosives to squeeze a small piece of plutonium into a very tight ball. This made the material denser and caused it to become supercritical, starting a chain reaction.

Important advances were made throughout 1943 and 1944. By July 1944, it was clear that the implosion design was the best option, and the whole laboratory was reorganized to focus on it. Scientists developed special shapes of explosives, called explosive lenses, to focus the blast evenly around the plutonium core. They tested their designs using a special experiment called the RaLa Experiment, which helped them understand how the explosion would behave. The final bomb, known as Fat Man, used these lenses to create a perfectly shaped blast that brought the plutonium together in a fraction of a second.

Little Boy

Main article: Little Boy

After a reorganization at the Los Alamos Laboratory in 1944, scientists focused on a uranium-based weapon design called Little Boy. This design was simpler than another type being developed and could fit inside a B-29 bomber. The bomb used enriched uranium and a gun mechanism to bring two pieces of uranium together to create a chain reaction.

The parts for Little Boy were made in different factories to keep the full design secret. By May 1945, most of the bomb was ready, and the final pieces of uranium were added in July. Although there was no full test of the bomb before use, scientists felt confident it would work because of earlier smaller tests. Little Boy was dropped on Hiroshima as part of World War II. Safety tests showed that an accident was very unlikely, but there were still concerns about possible radiation if the bomb crashed or was submerged in water.

Water boiler

The Water Boiler was an early nuclear reactor designed to test ideas about nuclear chain reactions. It used uranium dissolved in water as its fuel. This project began in 1943 as scientists tried to learn more about how reactors could work.

The reactor was built in a safe location away from the main laboratory. It was completed and began operating in May 1944, becoming only the third reactor ever to function. Scientists used it to study many aspects of nuclear reactions and improve their understanding of how reactors could be built and operated.

Super

Main article: History of the Teller–Ulam design

Scientists worked on a project called the "Super," which aimed to create even more powerful bombs than the first atomic bombs. Edward Teller led this research and believed it was possible to build these super bombs. He and his team, including scientists like Emil Konopinski and Stanislaw Ulam, studied how to make the Super work. They looked at using materials like deuterium and tritium to create huge amounts of energy.

Even though the main focus was on building the first atomic bombs, the idea of these super bombs kept scientists interested. By 1946, they had made many calculations and plans, but it would later be discovered that the original ideas for the Super would not actually work as hoped.

Trinity

Main article: Trinity (nuclear test)

The first atomic bomb test, called "Trinity," was carried out to check how well a new type of bomb would work. It took place on July 16, 1945, in the desert near Alamogordo Army Airfield. Scientists built a tall tower and placed the bomb on top of it. When the bomb exploded, it created a huge flash of light and a mushroom cloud that rose high into the sky. The explosion was very powerful, equal to about 20,000 tons of dynamite. It left a large crater in the ground and made a shock wave that could be felt far away. This test helped scientists and military leaders understand how effective their new weapon was before using it in World War II.

Project Alberta

Main article: Project Alberta

Project Alberta, also called Project A, was created in March 1945 to help prepare and deliver atomic bombs. It was led by William Parsons and included scientists and military personnel who volunteered for this important mission. Their job was to get the bombs ready and plan how to use them.

The team worked hard to have the bombs ready by August 1945. They tested many parts and flew practice missions using practice bombs called "pumpkin bombs." When the time came, they assembled the real bombs and loaded them onto special planes. Some of these planes took part in missions over Japan, with crew members from Project Alberta on board to watch and record what happened.

Health and safety

A medical program was started at Los Alamos under Captain James Findley Nolan of the United States Army Medical Corps. It began with small infirmaries for civilians and military personnel, but later grew into a larger hospital to better care for everyone. Some research was done on the effects of radiation and metals like plutonium.

Unfortunately, there were many accidents during the time the laboratory was open. Some workers were hurt, and a few scientists died in accidents involving special materials used in their work. Safety measures were improved over time to protect everyone.

Security

Main article: Atomic spies

During World War II, there was great concern for the safety of the Los Alamos Laboratory because of its secret work on atomic bombs. One day, a Japanese fire balloon struck a power line, causing a shutdown of reactors and making everyone worried about possible attacks.

Keeping the project safe was very hard with so many people involved. A special group was formed to handle security, and it was discovered that some people were trying to share the secret information with the Soviet Union. Several spies were later uncovered, which created tension between the United States, Britain, and Canada.

Post-war

After World War II ended, J. Robert Oppenheimer decided to leave his role as director of the Los Alamos Laboratory. Norris Bradbury took over as the new director in October 1945. Bradbury faced many challenges, as many scientists wanted to return to their universities and the new Atomic Energy Act had not yet been passed.

During this time, the laboratory still needed to support important nuclear tests called Operation Crossroads in the Pacific Ocean. The number of people working at Los Alamos decreased from over 3,000 during the war to about 1,000, but the work continued. The Los Alamos Laboratory was renamed the Los Alamos Scientific Laboratory in January 1947, and Bradbury led it until 1970.