A report on Nuclear weapon design, Project Y and Stanislaw Ulam

The first nuclear explosive devices, cumbersome and inefficient, provided the basic design building blocks of all future weapons. Pictured is the Gadget device being prepared for the first nuclear test, Trinity.

Robert Oppenheimer (left), Leslie Groves (center) and Robert Sproul (right) at the ceremony to present the Los Alamos Laboratory with the Army-Navy "E" Award at the Fuller Lodge on 16 October 1945

In nuclear fission, the atomic nucleus of a heavy element splits into two or more light ones when a neutron is captured. If more neutrons are emitted, a nuclear chain reaction becomes possible.

In nuclear fusion, the nuclei of light elements are fused to create a heavier element.

The Scottish Café's building now houses the Universal Bank in Lviv, Ukraine.

Map of Los Alamos site, New Mexico, 1943–45

Four-family apartment units at Los Alamos

Flash X-Ray images of the converging shock waves formed during a test of the high explosive lens system.

The Technical Area at Los Alamos. There was a perimeter fence around the entire site, but also an inner fence shown here around the Technical Area.

Ivy Mike, the first full test of the Teller–Ulam design (a staged fusion bomb), with a yield of 10.4 megatons on 1 November 1952

The Sausage device of Mike nuclear test (yield 10.4 Mt) on Enewetak Atoll. The test was part of the Operation Ivy. The Sausage was the first true H-Bomb ever tested, meaning the first thermonuclear device built upon the Teller-Ulam principles of staged radiation implosion.

Passage between buildings A and B in the Technical Area

An artist's conception of the NASA reference design for the Project Orion spacecraft powered by nuclear propulsion

Isidor Isaac Rabi, Dorothy McKibbin, Robert Oppenheimer and Victor Weisskopf at Oppenheimer's home in Los Alamos in 1944

When the positive integers are arrayed along the Ulam spiral, prime numbers, represented by dots, tend to collect along diagonal lines.

Ivy Mike, the first two-stage thermonuclear detonation, 10.4 megatons, November 1, 1952.

A row of Thin Man casings. Fat Man casings are visible in the background. The tow truck was used by the 216th Army Air Forces Base Unit to move them.

An animation demonstrating the lucky number sieve. The numbers in red are lucky numbers

Bassoon, the prototype for a 9.3-megaton clean bomb or a 25-megaton dirty bomb. Dirty version shown here, before its 1956 test. The two attachments on the left are light pipes; see below for elaboration.

A ring of electrorefined plutonium. It has a purity of 99.96%, weighs 5.3 kg, and is about 11 cm in diameter. It is enough plutonium for one bomb core. The ring shape helps with criticality safety.

Plutonium has six allotropes at ambient pressure: alpha (α), beta (β), gamma (γ), delta (δ), delta prime (δ'), & epsilon (ε)

Subsidence Craters at Yucca Flat, Nevada Test Site.

Explosive lenses are used to compress a fissile core inside an implosion-type nuclear weapon.

A diagram of the Green Grass warhead's steel ball safety device, shown left, filled (safe) and right, empty (live). The steel balls were emptied into a hopper underneath the aircraft before flight, and could be re-inserted using a funnel by rotating the bomb on its trolley and raising the hopper.

An implosion-type nuclear bomb. In the center is the neutron initiator (red). It is surrounded by the plutonium hemispheres. There is a small air gap (white, not in the original Fat Man design) and then the uranium tamper. Around that is the aluminium pusher (purple). This is encased in the explosive lenses (gold). Colors are the same as in the diagram opposite.

Norris Bradbury, group leader for bomb assembly, stands next to the partially assembled Gadget atop the Trinity test tower. Later, he became the director of Los Alamos vice Oppenheimer.

A Little Boy unit on Tinian connected to test equipment, possibly to test or charge components within the device

The April 1946 colloquium on the Super. In the front row are (left to right) Norris Bradbury, John Manley, Enrico Fermi and J. M. B. Kellogg. Robert Oppenheimer, in dark coat, is behind Manley; to Oppenheimer's left is Richard Feynman. The Army officer on the left is Colonel Oliver Haywood.

Herbert Lehr and Harry Daghlian loading the assembled tamper plug containing the plutonium pit and initiator into a sedan for transport from the McDonald Ranch House to the Trinity shot tower

The explosives of "the gadget" were raised to the top of the tower for the final assembly.

Deak Parsons (right) supervises loading the Little Boy bomb into the B-29 Enola Gay. Norman Ramsey is on his left, with his back to the camera.

Fat Man bomb, with liquid asphalt sealant sprayed on the casing's seams, is readied on Tinian.

Remote handling of a kilocurie source of radiolanthanum for a RaLa Experiment at Los Alamos

Bradbury (left) examines plans for new laboratory sites and permanent housing with Leslie Groves of the Armed Forces Special Weapons Project (center) and Eric Jette (right) in April 1947; Colonel Lyle E. Seeman stands behind Bradbury, second from the left.

Oppenheimer then reorganized the laboratory and orchestrated an all-out and ultimately successful effort on an alternative design proposed by John von Neumann, an implosion-type nuclear weapon, which was called Fat Man.

- Project Y

In October 1943, he received an invitation from Hans Bethe to join the Manhattan Project at the secret Los Alamos Laboratory in New Mexico.

- Stanislaw Ulam

There, he worked on the hydrodynamic calculations to predict the behavior of the explosive lenses that were needed by an implosion-type weapon.

- Stanislaw Ulam

The series of RaLa Experiment tests of implosion-type fission weapon design concepts, carried out from July 1944 through February 1945 at the Los Alamos Laboratory and a remote site 14.3 km (9 miles) east of it in Bayo Canyon, proved the practicality of the implosion design for a fission device, with the February 1945 tests positively determining its usability for the final Trinity/Fat Man plutonium implosion design.

- Nuclear weapon design

The design breakthrough came in January 1951, when Edward Teller and Stanislaw Ulam invented radiation implosion – for nearly three decades known publicly only as the Teller-Ulam H-bomb secret.

- Nuclear weapon design

Nonetheless, in February 1944, Teller added Stanislaw Ulam, Jane Roberg, Geoffrey Chew, and Harold and Mary Argo to his T-1 Group.

- Project Y

3 related topics with Alpha

Manhattan Project

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Research and development undertaking during World War II that produced the first nuclear weapons.

Enrico Fermi, John R. Dunning, and Dana P. Mitchell in front of the cyclotron in the basement of Pupin Hall at Columbia University

March 1940 meeting at Berkeley, California: Ernest O. Lawrence, Arthur H. Compton, Vannevar Bush, James B. Conant, Karl T. Compton, and Alfred L. Loomis

Different fission bomb assembly methods explored during the July 1942 conference

Manhattan Project Organization Chart, 1 May 1946

Oppenheimer and Groves at the remains of the Trinity test in September 1945, two months after the test blast and just after the end of World War II. The white overshoes prevented fallout from sticking to the soles of their shoes.

Groves confers with James Chadwick, the head of the British Mission.

Shift change at the Y-12 uranium enrichment facility at the Clinton Engineer Works in Oak Ridge, Tennessee, on 11 August 1945. By May 1945, 82,000 people were employed at the Clinton Engineer Works. Photograph by the Manhattan District photographer Ed Westcott.

Physicists at a Manhattan District-sponsored colloquium at the Los Alamos Laboratory on the Super in April 1946. In the front row are Norris Bradbury, John Manley, Enrico Fermi and J. (Jerome) M. B. Kellogg (1905-1981). Robert Oppenheimer, in dark coat, is behind Manley; to Oppenheimer's left is Richard Feynman. The Army officer on the left is Colonel Oliver Haywood.

Hanford workers collect their paychecks at the Western Union office.

The majority of the uranium used in the Manhattan Project came from the Shinkolobwe mine in Belgian Congo.

Oak Ridge hosted several uranium separation technologies. The Y-12 electromagnetic separation plant is in the upper right. The K-25 and K-27 gaseous diffusion plants are in the lower left, near the S-50 thermal diffusion plant. The X-10 was for plutonium production.

Calutron Girls were young women who monitored calutron control panels at Y-12. Gladys Owens, seated in the foreground, was unaware of what she had been involved in.

The S-50 plant is the dark building to the upper left behind the Oak Ridge powerhouse (with smoke stacks).

Workers load uranium slugs into the X-10 Graphite Reactor.

Aerial view of Hanford B-Reactor site, June 1944

Map of the Hanford Site. Railroads flank the plants to the north and south. Reactors are the three northernmost red squares, along the Columbia River. The separation plants are the lower two red squares from the grouping south of the reactors. The bottom red square is the 300 area.

A row of Thin Man casings. Fat Man casings are visible in the background.

The Trinity test of the Manhattan Project was the first detonation of a nuclear weapon.

Major General Leslie R. Groves, Jr., speaks to service personnel Oak Ridge Tennessee in August 1945.

A billboard encouraging secrecy among Oak Ridge workers

Security poster, warning office workers to close drawers and put documents in safes when not being used

Allied soldiers dismantle the German experimental nuclear reactor at Haigerloch.

Silverplate B-29 Straight Flush. The tail code of the 444th Bombardment Group is painted on for security reasons.

Little Boy explodes over Hiroshima, Japan, 6 August 1945 (left);
Fat Man explodes over Nagasaki, Japan, 9 August 1945 (right).

Presentation of the Army–Navy "E" Award at Los Alamos on 16 October 1945. Standing, left to right: J. Robert Oppenheimer, unidentified, unidentified, Kenneth Nichols, Leslie Groves, Robert Gordon Sproul, William Sterling Parsons.

President Harry S. Truman signs the Atomic Energy Act of 1946, establishing the United States Atomic Energy Commission.

The Lake Ontario Ordnance Works (LOOW) near Niagara Falls became a principal repository for Manhattan Project waste for the Eastern United States. All of the radioactive materials stored at the LOOW site—including thorium, uranium, and the world's largest concentration of radium-226—were buried in an "Interim Waste Containment Structure" (in the foreground) in 1991.

A "bomb" (pressure vessel) containing uranium halide and sacrificial metal, probably magnesium, being lowered into a furnace

After the reaction, the interior of a bomb coated with remnant slag

A uranium metal "biscuit" from the reduction reaction

Nuclear physicist Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the actual bombs.

The Project let to the development of two types of atomic bombs, both developed concurrently, during the war: a relatively simple gun-type fission weapon and a more complex implosion-type nuclear weapon.

At the University of Wisconsin–Madison, Stanislaw Ulam gave one of his students, Joan Hinton, an exam early, so she could leave to do war work.

Edward Teller

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Hungarian-American theoretical physicist who is known colloquially as "the father of the hydrogen bomb" (see the Teller–Ulam design), although he did not care for the title, considering it to be in poor taste.

Physicists at a Manhattan District-sponsored colloquium at Los Alamos on the Super in April 1946. In the front row are (left to right) Norris Bradbury, John Manley, Enrico Fermi and J. M. B. Kellogg. Robert Oppenheimer, in dark coat, is behind Manley; to Oppenheimer's left is Richard Feynman. The Army officer on the left is Colonel Oliver Haywood.

The Teller–Ulam design kept the fission and fusion fuel physically separated from one another, and used X-rays from the primary device "reflected" off the surrounding casing to compress the secondary.

The 10.4 Mt "Ivy Mike" shot of 1952 appeared to vindicate Teller's long-time advocacy for the hydrogen bomb.

Teller testified about J. Robert Oppenheimer in 1954.

One of the Chariot schemes involved chaining five thermonuclear devices to create the artificial harbor.

Teller became a major lobbying force of the Strategic Defense Initiative to President Ronald Reagan in the 1980s.

Appearing on British television discussion After Dark in 1987

In early 1943, the Los Alamos Laboratory was established in Los Alamos, New Mexico to design an atomic bomb, with Oppenheimer as its director.

A special group was established under Teller in March 1944 to investigate the mathematics of an implosion-type nuclear weapon.

It included Stanislaw Ulam, Jane Roberg, Geoffrey Chew, Harold and Mary Argo, and Maria Goeppert-Mayer.

J. Robert Oppenheimer

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American theoretical physicist.

Heike Kamerlingh Onnes' Laboratory in Leiden, Netherlands, 1926. Oppenheimer is in the middle row, second from the left.

The University of California, Berkeley, where Oppenheimer taught from 1929 to 1943

Physicists Albert Einstein and Oppenheimer conferring circa 1950

Oppenheimer's ID badge from the Los Alamos Laboratory

Presentation of the Army-Navy "E" Award at Los Alamos on October 16, 1945. Oppenheimer (left) gave his farewell speech as director on this occasion. Robert Gordon Sproul right, in suit, accepted the award on behalf of the University of California from Leslie Groves (center).

A group of physicists at the 1946 Los Alamos colloquium on the Super. In the front row are Norris Bradbury, John Manley, Enrico Fermi and J.M.B. Kellogg. Behind Manley is Oppenheimer (wearing jacket and tie), and to his left is Richard Feynman. The army colonel on the far left is Oliver Haywood. In the third row between Haywood and Oppenheimer is Edward Teller.

The Trinity test of the Manhattan Project was the first detonation of a nuclear device.

Oppenheimer's Van Gogh, Enclosed Field with Rising Sun (1889).

Institute for Advanced Study in Princeton, New Jersey

Oppenheimer in 1946 with his trademark cigarette

President Dwight D. Eisenhower receives a report from Lewis L. Strauss, Chairman of the Atomic Energy Commission, on the Operation Castle hydrogen bomb tests in the Pacific, March 30, 1954. Strauss pressed for Oppenheimer's security clearance to be revoked.

Oppenheimer's former colleague, physicist Edward Teller, testified on behalf of the government at Oppenheimer's security hearing in 1954.

Oppenheimer Beach, in Saint John, U.S. Virgin Islands

Award of honorary degrees at Harvard to Oppenheimer (left), George C. Marshall (third from left) and Omar N. Bradley (fifth from left). The President of Harvard University, James B. Conant, sits between Marshall and Bradley. June 5, 1947

Oppenheimer and Leslie Groves in September 1945 at the remains of the Trinity test in New Mexico. The white canvas overshoes prevented fallout from sticking to the soles of their shoes.

J. Robert Oppenheimer giving a speech during a 1966 visit to Israel

A professor of physics at the University of California, Berkeley, Oppenheimer was the wartime head of the Los Alamos Laboratory and is often credited as the "father of the atomic bomb" for his role in the Manhattan Project – the World War II undertaking that developed the first nuclear weapons.

In July 1944, Oppenheimer abandoned the gun design in favor of an implosion-type weapon.

In 1951, Edward Teller and mathematician Stanislaw Ulam developed what became known as the Teller-Ulam design for a hydrogen bomb.